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| | | * | | | | | | | | | | | | | | rcu: Simplify priority boosting by putting rt_mutex in rcu_nodePaul E. McKenney2014-07-09
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | RCU priority boosting currently checks for boosting via a pointer in task_struct. However, this is not needed: As Oleg noted, if the rt_mutex is placed in the rcu_node instead of on the booster's stack, the boostee can simply check it see if it owns the lock. This commit makes this change, shrinking task_struct by one pointer and the kernel by thirteen lines. Suggested-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
| | | * | | | | | | | | | | | | | | rcu: Check both root and current rcu_node when setting up future grace periodPranith Kumar2014-07-09
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The rcu_start_future_gp() function checks the current rcu_node's ->gpnum and ->completed twice, once without ACCESS_ONCE() and once with it. Which is pointless because we hold that rcu_node's ->lock at that point. The intent was to check the current rcu_node structure and the root rcu_node structure, the latter locklessly with ACCESS_ONCE(). This commit therefore makes that change. The reason that it is safe to locklessly check the root rcu_nodes's ->gpnum and ->completed fields is that we hold the current rcu_node's ->lock, which constrains the root rcu_node's ability to change its ->gpnum and ->completed fields. Of course, if there is a single rcu_node structure, then rnp_root==rnp, and holding the lock prevents all changes. If there is more than one rcu_node structure, then the code updates the fields in the following order: 1. Increment rnp_root->gpnum to start new grace period. 2. Increment rnp->gpnum to initialize the current rcu_node, continuing initialization for the new grace period. 3. Increment rnp_root->completed to end the current grace period. 4. Increment rnp->completed to continue cleaning up after the old grace period. So there are four possible combinations of relative values of these four fields: N N N N: RCU idle, new grace period must be initiated. Although rnp_root->gpnum might be incremented immediately after we check, that will just result in unnecessary work. The grace period already started, and we try to start it. N+1 N N N: RCU grace period just started. No further change is possible because we hold rnp->lock, so the checks of rnp_root->gpnum and rnp_root->completed are stable. We know that our request for a future grace period will be seen during grace-period cleanup. N+1 N N+1 N: RCU grace period is ongoing. Because rnp->gpnum is different than rnp->completed, we won't even look at rnp_root->gpnum and rnp_root->completed, so the possible concurrent change to rnp_root->completed does not matter. We know that our request for a future grace period will be seen during grace-period cleanup, which cannot pass this rcu_node because we hold its ->lock. N+1 N+1 N+1 N: RCU grace period has ended, but not yet been cleaned up. Because rnp->gpnum is different than rnp->completed, we won't look at rnp_root->gpnum and rnp_root->completed, so the possible concurrent change to rnp_root->completed does not matter. We know that our request for a future grace period will be seen during grace-period cleanup, which cannot pass this rcu_node because we hold its ->lock. Therefore, despite initial appearances, the lockless check is safe. Signed-off-by: Pranith Kumar <bobby.prani@gmail.com> [ paulmck: Update comment to say why the lockless check is safe. ] Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
| | | * | | | | | | | | | | | | | | rcu: Allow post-unlock reference for rt_mutexPaul E. McKenney2014-07-09
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The current approach to RCU priority boosting uses an rt_mutex strictly for its priority-boosting side effects. The rt_mutex_init_proxy_locked() function is used by the booster to initialize the lock as held by the boostee. The booster then uses rt_mutex_lock() to acquire this rt_mutex, which priority-boosts the boostee. When the boostee reaches the end of its outermost RCU read-side critical section, it checks a field in its task structure to see whether it has been boosted, and, if so, uses rt_mutex_unlock() to release the rt_mutex. The booster can then go on to boost the next task that is blocking the current RCU grace period. But reasonable implementations of rt_mutex_unlock() might result in the boostee referencing the rt_mutex's data after releasing it. But the booster might have re-initialized the rt_mutex between the time that the boostee released it and the time that it later referenced it. This is clearly asking for trouble, so this commit introduces a completion that forces the booster to wait until the boostee has completely finished with the rt_mutex, thus avoiding the case where the booster is re-initializing the rt_mutex before the last boostee's last reference to that rt_mutex. This of course does introduce some overhead, but the priority-boosting code paths are miles from any possible fastpath, and the overhead of executing the completion will normally be quite small compared to the overhead of priority boosting and deboosting, so this should be OK. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
| | | * | | | | | | | | | | | | | | rcu: Loosen __call_rcu()'s rcu_head alignment constraintPaul E. McKenney2014-07-09
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The m68k architecture aligns only to 16-bit boundaries, which can cause the align-to-32-bits check in __call_rcu() to trigger. Because there is currently no known potential need for more than one low-order bit, this commit loosens the check to 16-bit boundaries. Reported-by: Greg Ungerer <gerg@uclinux.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
| | | * | | | | | | | | | | | | | | rcu: Eliminate read-modify-write ACCESS_ONCE() callsPaul E. McKenney2014-07-09
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | RCU contains code of the following forms: ACCESS_ONCE(x)++; ACCESS_ONCE(x) += y; ACCESS_ONCE(x) -= y; Now these constructs do operate correctly, but they really result in a pair of volatile accesses, one to do the load and another to do the store. This can be confusing, as the casual reader might well assume that (for example) gcc might generate a memory-to-memory add instruction for each of these three cases. In fact, gcc will do no such thing. Also, there is a good chance that the kernel will move to separate load and store variants of ACCESS_ONCE(), and constructs like the above could easily confuse both people and scripts attempting to make that sort of change. Finally, most of RCU's read-modify-write uses of ACCESS_ONCE() really only need the store to be volatile, so that the read-modify-write form might be misleading. This commit therefore changes the above forms in RCU so that each instance of ACCESS_ONCE() either does a load or a store, but not both. In a few cases, ACCESS_ONCE() was not critical, for example, for maintaining statisitics. In these cases, ACCESS_ONCE() has been dispensed with entirely. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
| | | * | | | | | | | | | | | | | | rcu: Remove redundant ACCESS_ONCE() from tick_do_timer_cpuPaul E. McKenney2014-07-09
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In kernels built with CONFIG_NO_HZ_FULL, tick_do_timer_cpu is constant once boot completes. Thus, there is no need to wrap it in ACCESS_ONCE() in code that is built only when CONFIG_NO_HZ_FULL. This commit therefore removes the redundant ACCESS_ONCE(). Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Frederic Weisbecker <fweisbec@gmail.com> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
| | | * | | | | | | | | | | | | | | rcu: Make rcu node arrays static const char * constFabian Frederick2014-07-09
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Those two arrays are being passed to lockdep_init_map(), which expects const char *, and are stored in lockdep_map the same way. Cc: Dipankar Sarma <dipankar@in.ibm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Fabian Frederick <fabf@skynet.be> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
| | | * | | | | | | | | | | | | | | signal: Explain local_irq_save() callPaul E. McKenney2014-07-09
| | |/ / / / / / / / / / / / / / / | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The explicit local_irq_save() in __lock_task_sighand() is needed to avoid a potential deadlock condition, as noted in a841796f11c90d53 (signal: align __lock_task_sighand() irq disabling and RCU). However, someone reading the code might be forgiven for concluding that this separate local_irq_save() was completely unnecessary. This commit therefore adds a comment referencing the shiny new block comment on rcu_read_unlock(). Reported-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Oleg Nesterov <oleg@redhat.com> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
* | | | | | | | | | | | | | | | | Merge tag 'trace-3.17-2' of ↵Linus Torvalds2014-08-04
|\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull tracing filter cleanups from Steven Rostedt: "Oleg Nesterov did several clean ups with the tracing filter code. As he found some small bugs that went into 3.16, and these changes were based on that, I had to apply his changes to a separate branch than my main development branch. This was based on work that was already pulled into 3.16, and is a separate pull request to keep from having local merges in my pull request" * tag 'trace-3.17-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: tracing: Kill "filter_string" arg of replace_preds() tracing: Change apply_subsystem_event_filter() paths to check file->system == dir tracing: Kill ftrace_event_call->files tracing/uprobes: Kill the dead TRACE_EVENT_FL_USE_CALL_FILTER logic tracing: Kill call_filter_disable() tracing: Kill destroy_call_preds() tracing: Kill destroy_preds() and destroy_file_preds()
| * | | | | | | | | | | | | | | | | tracing: Kill "filter_string" arg of replace_preds()Oleg Nesterov2014-07-16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Cosmetic, but replace_preds() doesn't need/use "char *filter_string". Remove it to microsimplify the code. Link: http://lkml.kernel.org/p/20140715184832.GA20519@redhat.com Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | tracing: Change apply_subsystem_event_filter() paths to check file->system ↵Oleg Nesterov2014-07-16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | == dir filter_free_subsystem_preds(), filter_free_subsystem_filters() and replace_system_preds() can simply check file->system->subsystem and avoid strcmp(call->class->system). Better yet, we can pass "struct ftrace_subsystem_dir *dir" instead of event_subsystem and just check file->system == dir. Thanks to Namhyung Kim who pointed out that replace_system_preds() can be changed too. Link: http://lkml.kernel.org/p/20140715184829.GA20516@redhat.com Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | tracing/uprobes: Kill the dead TRACE_EVENT_FL_USE_CALL_FILTER logicOleg Nesterov2014-07-16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | alloc_trace_uprobe() sets TRACE_EVENT_FL_USE_CALL_FILTER for unknown reason and this is simply wrong. Fortunately this has no effect because register_uprobe_event() clears call->flags after that. Kill both. This trace_uprobe was kzalloc'ed and we rely on this fact anyway. Link: http://lkml.kernel.org/p/20140715184824.GA20505@redhat.com Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | tracing: Kill call_filter_disable()Oleg Nesterov2014-07-16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | It seems that the only purpose of call_filter_disable() is to make filter_disable() less clear and symmetrical, remove it. Link: http://lkml.kernel.org/p/20140715184821.GA20498@redhat.com Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | tracing: Kill destroy_call_preds()Oleg Nesterov2014-07-16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Remove destroy_call_preds(). Its only caller, __trace_remove_event_call(), can use free_event_filter() and nullify ->filter by hand. Perhaps we could keep this trivial helper although imo it is pointless, but then it should be static in trace_events.c. Link: http://lkml.kernel.org/p/20140715184816.GA20495@redhat.com Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | tracing: Kill destroy_preds() and destroy_file_preds()Oleg Nesterov2014-07-16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | destroy_preds() makes no sense. The only caller, event_remove(), actually wants destroy_file_preds(). __trace_remove_event_call() does destroy_call_preds() which takes care of call->filter. And after the previous change we can simply remove destroy_preds() from event_remove(), we are going to call remove_event_from_tracers() which in turn calls remove_event_file_dir()->free_event_filter(). Link: http://lkml.kernel.org/p/20140715184813.GA20488@redhat.com Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* | | | | | | | | | | | | | | | | | Merge tag 'trace-3.17' of ↵Linus Torvalds2014-08-04
|\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull tracing updates from Steven Rostedt: "This pull request has a lot of work done. The main thing is the changes to the ftrace function callback infrastructure. It's introducing a way to allow different functions to call directly different trampolines instead of all calling the same "mcount" one. The only user of this for now is the function graph tracer, which always had a different trampoline, but the function tracer trampoline was called and did basically nothing, and then the function graph tracer trampoline was called. The difference now, is that the function graph tracer trampoline can be called directly if a function is only being traced by the function graph trampoline. If function tracing is also happening on the same function, the old way is still done. The accounting for this takes up more memory when function graph tracing is activated, as it needs to keep track of which functions it uses. I have a new way that wont take as much memory, but it's not ready yet for this merge window, and will have to wait for the next one. Another big change was the removal of the ftrace_start/stop() calls that were used by the suspend/resume code that stopped function tracing when entering into suspend and resume paths. The stop of ftrace was done because there was some function that would crash the system if one called smp_processor_id()! The stop/start was a big hammer to solve the issue at the time, which was when ftrace was first introduced into Linux. Now ftrace has better infrastructure to debug such issues, and I found the problem function and labeled it with "notrace" and function tracing can now safely be activated all the way down into the guts of suspend and resume Other changes include clean ups of uprobe code, clean up of the trace_seq() code, and other various small fixes and clean ups to ftrace and tracing" * tag 'trace-3.17' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (57 commits) ftrace: Add warning if tramp hash does not match nr_trampolines ftrace: Fix trampoline hash update check on rec->flags ring-buffer: Use rb_page_size() instead of open coded head_page size ftrace: Rename ftrace_ops field from trampolines to nr_trampolines tracing: Convert local function_graph functions to static ftrace: Do not copy old hash when resetting tracing: let user specify tracing_thresh after selecting function_graph ring-buffer: Always run per-cpu ring buffer resize with schedule_work_on() tracing: Remove function_trace_stop and HAVE_FUNCTION_TRACE_MCOUNT_TEST s390/ftrace: remove check of obsolete variable function_trace_stop arm64, ftrace: Remove check of obsolete variable function_trace_stop Blackfin: ftrace: Remove check of obsolete variable function_trace_stop metag: ftrace: Remove check of obsolete variable function_trace_stop microblaze: ftrace: Remove check of obsolete variable function_trace_stop MIPS: ftrace: Remove check of obsolete variable function_trace_stop parisc: ftrace: Remove check of obsolete variable function_trace_stop sh: ftrace: Remove check of obsolete variable function_trace_stop sparc64,ftrace: Remove check of obsolete variable function_trace_stop tile: ftrace: Remove check of obsolete variable function_trace_stop ftrace: x86: Remove check of obsolete variable function_trace_stop ...
| * | | | | | | | | | | | | | | | | | ftrace: Add warning if tramp hash does not match nr_trampolinesSteven Rostedt (Red Hat)2014-07-24
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | After adding all the records to the tramp_hash, add a check that makes sure that the number of records added matches the number of records expected to match and do a WARN_ON and disable ftrace if they do not match. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | | ftrace: Fix trampoline hash update check on rec->flagsSteven Rostedt (Red Hat)2014-07-24
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In the loop of ftrace_save_ops_tramp_hash(), it adds all the recs to the ops hash if the rec has only one callback attached and the ops is connected to the rec. It gives a nasty warning and shuts down ftrace if the rec doesn't have a trampoline set for it. But this can happen with the following scenario: # cd /sys/kernel/debug/tracing # echo schedule do_IRQ > set_ftrace_filter # mkdir instances/foo # echo schedule > instances/foo/set_ftrace_filter # echo function_graph > current_function # echo function > instances/foo/current_function # echo nop > instances/foo/current_function The above would then trigger the following warning and disable ftrace: ------------[ cut here ]------------ WARNING: CPU: 0 PID: 3145 at kernel/trace/ftrace.c:2212 ftrace_run_update_code+0xe4/0x15b() Modules linked in: ipt_MASQUERADE sunrpc ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ip [...] CPU: 1 PID: 3145 Comm: bash Not tainted 3.16.0-rc3-test+ #136 Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./To be filled by O.E.M., BIOS SDBLI944.86P 05/08/2007 0000000000000000 ffffffff81808a88 ffffffff81502130 0000000000000000 ffffffff81040ca1 ffff880077c08000 ffffffff810bd286 0000000000000001 ffffffff81a56830 ffff88007a041be0 ffff88007a872d60 00000000000001be Call Trace: [<ffffffff81502130>] ? dump_stack+0x4a/0x75 [<ffffffff81040ca1>] ? warn_slowpath_common+0x7e/0x97 [<ffffffff810bd286>] ? ftrace_run_update_code+0xe4/0x15b [<ffffffff810bd286>] ? ftrace_run_update_code+0xe4/0x15b [<ffffffff810bda1a>] ? ftrace_shutdown+0x11c/0x16b [<ffffffff810bda87>] ? unregister_ftrace_function+0x1e/0x38 [<ffffffff810cc7e1>] ? function_trace_reset+0x1a/0x28 [<ffffffff810c924f>] ? tracing_set_tracer+0xc1/0x276 [<ffffffff810c9477>] ? tracing_set_trace_write+0x73/0x91 [<ffffffff81132383>] ? __sb_start_write+0x9a/0xcc [<ffffffff8120478f>] ? security_file_permission+0x1b/0x31 [<ffffffff81130e49>] ? vfs_write+0xac/0x11c [<ffffffff8113115d>] ? SyS_write+0x60/0x8e [<ffffffff81508112>] ? system_call_fastpath+0x16/0x1b ---[ end trace 938c4415cbc7dc96 ]--- ------------[ cut here ]------------ Link: http://lkml.kernel.org/r/20140723120805.GB21376@redhat.com Reported-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | | ring-buffer: Use rb_page_size() instead of open coded head_page sizeSteven Rostedt (Red Hat)2014-07-23
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There's a helper function to get a ring buffer page size (the number of bytes of data recorded on the page), called rb_page_size(). Use that instead of open coding it. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | | ftrace: Rename ftrace_ops field from trampolines to nr_trampolinesSteven Rostedt (Red Hat)2014-07-23
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Having two fields within the same struct that is off by one character can be confusing and error prone. Rename the counter "trampolines" to "nr_trampolines" to explicitly show it is a counter and not to be confused by the "trampoline" field. Suggested-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | | tracing: Convert local function_graph functions to staticSteven Rostedt (Red Hat)2014-07-18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Local functions should be static. Reported-by: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | | ftrace: Do not copy old hash when resettingWang Nan2014-07-18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Do not waste time copying the old hash if the hash is going to be reset. Just allocate a new hash and free the old one, as that is the same result as copying te old one and then resetting it. Link: http://lkml.kernel.org/p/1405384820-48837-1-git-send-email-wangnan0@huawei.com Signed-off-by: Wang Nan <wangnan0@huawei.com> [ SDR: Removed unused ftrace_filter_reset() function ] Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | | tracing: let user specify tracing_thresh after selecting function_graphStanislav Fomichev2014-07-18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, tracing_thresh works only if we specify it before selecting function_graph tracer. If we do the opposite, tracing_thresh will change it's value, but it will not be applied. To fix it, we add update_thresh callback which is called whenever tracing_thresh is updated and for function_graph tracer we register handler which reinitializes tracer depending on tracing_thresh. Link: http://lkml.kernel.org/p/20140718111727.GA3206@stfomichev-desktop.yandex.net Signed-off-by: Stanislav Fomichev <stfomichev@yandex-team.ru> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | | ring-buffer: Always run per-cpu ring buffer resize with schedule_work_on()Corey Minyard2014-07-18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The code for resizing the trace ring buffers has to run the per-cpu resize on the CPU itself. The code was using preempt_off() and running the code for the current CPU directly, otherwise calling schedule_work_on(). At least on RT this could result in the following: |BUG: sleeping function called from invalid context at kernel/rtmutex.c:673 |in_atomic(): 1, irqs_disabled(): 0, pid: 607, name: bash |3 locks held by bash/607: |CPU: 0 PID: 607 Comm: bash Not tainted 3.12.15-rt25+ #124 |(rt_spin_lock+0x28/0x68) |(free_hot_cold_page+0x84/0x3b8) |(free_buffer_page+0x14/0x20) |(rb_update_pages+0x280/0x338) |(ring_buffer_resize+0x32c/0x3dc) |(free_snapshot+0x18/0x38) |(tracing_set_tracer+0x27c/0x2ac) probably via |cd /sys/kernel/debug/tracing/ |echo 1 > events/enable ; sleep 2 |echo 1024 > buffer_size_kb If we just always use schedule_work_on(), there's no need for the preempt_off(). So do that. Link: http://lkml.kernel.org/p/1405537633-31518-1-git-send-email-cminyard@mvista.com Reported-by: Stanislav Meduna <stano@meduna.org> Signed-off-by: Corey Minyard <cminyard@mvista.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | | tracing: Remove function_trace_stop and HAVE_FUNCTION_TRACE_MCOUNT_TESTSteven Rostedt (Red Hat)2014-07-18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | All users of function_trace_stop and HAVE_FUNCTION_TRACE_MCOUNT_TEST have been removed. We can safely remove them from the kernel. Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | | ftrace: Remove function_trace_stop check from list funcSteven Rostedt (Red Hat)2014-07-18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | function_trace_stop is no longer used to stop function tracing. Remove the check from __ftrace_ops_list_func(). Also, call FTRACE_WARN_ON() instead of setting function_trace_stop if a ops has no func to call. Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | | ftrace: Do no disable function tracing on enabling function tracingSteven Rostedt (Red Hat)2014-07-18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When function tracing is being updated function_trace_stop is set to keep from tracing the updates. This was fine when function tracing was done from stop machine. But it is no longer done that way and this can cause real tracing to be missed. Remove it. Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | | ftrace-graph: Remove usage of ftrace_stop() in ftrace_graph_stop()Steven Rostedt (Red Hat)2014-07-18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | All archs now use ftrace_graph_is_dead() to stop function graph tracing. Remove the usage of ftrace_stop() as that is no longer needed. Cc: Frederic Weisbecker <fweisbec@gmail.com> Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | | ftrace-graph: Remove dependency of ftrace_stop() from ftrace_graph_stop()Steven Rostedt (Red Hat)2014-07-17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | ftrace_stop() is going away as it disables parts of function tracing that affects users that should not be affected. But ftrace_graph_stop() is built on ftrace_stop(). Here's another example of killing all of function tracing because something went wrong with function graph tracing. Instead of disabling all users of function tracing on function graph error, disable only function graph tracing. A new function is created called ftrace_graph_is_dead(). This is called in strategic paths to prevent function graph from doing more harm and allowing at least a warning to be printed before the system crashes. NOTE: ftrace_stop() is still used until all the archs are converted over to use ftrace_graph_is_dead(). After that, ftrace_stop() will be removed. Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | | PM / Sleep: Remove ftrace_stop/start() from suspend and hibernateSteven Rostedt (Red Hat)2014-07-17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | ftrace_stop() and ftrace_start() were added to the suspend and hibernate process because there was some function within the work flow that caused the system to reboot if it was traced. This function has recently been found (restore_processor_state()). Now there's no reason to disable function tracing while we are going into suspend or hibernate, which means that being able to trace this will help tremendously in debugging any issues with suspend or hibernate. This also means that the ftrace_stop/start() functions can be removed and simplify the function tracing code a bit. Link: http://lkml.kernel.org/r/1518201.VD9cU33jRU@vostro.rjw.lan Acked-by: "Rafael J. Wysocki" <rjw@rjwysocki.net> Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | | ftrace: Allow archs to specify if they need a separate function graph trampolineSteven Rostedt (Red Hat)2014-07-16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently if an arch supports function graph tracing, the core code will just assign the function graph trampoline to the function graph addr that gets called. But as the old method for function graph tracing always calls the function trampoline first and that calls the function graph trampoline, some archs may have the function graph trampoline dependent on operations that were done in the function trampoline. This causes function graph tracer to break on those archs. Instead of having the default be to set the function graph ftrace_ops to the function graph trampoline, have it instead just set it to zero which will keep it from jumping to a trampoline that is not set up to be jumped directly too. Link: http://lkml.kernel.org/r/53BED155.9040607@nvidia.com Reported-by: Tuomas Tynkkynen <ttynkkynen@nvidia.com> Tested-by: Tuomas Tynkkynen <ttynkkynen@nvidia.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | | Merge branch 'trace/ftrace/urgent' into trace/ftrace/coreSteven Rostedt (Red Hat)2014-07-09
| |\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Needed 099ed151675c "tracing: Remove ftrace_stop/start() from reading the trace file" for the removal of ftrace_start/stop().
| * | | | | | | | | | | | | | | | | | | tracing: Add description of set_graph_notrace to tracing/READMENamhyung Kim2014-07-01
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | It was missing the description of set_graph_notrace file. Add it. Link: http://lkml.kernel.org/p/1402590233-22321-5-git-send-email-namhyung@kernel.org Signed-off-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | | | tracing: Improve message of empty set_ftrace_notrace fileNamhyung Kim2014-07-01
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When there's no entry in set_ftrace_notrace, it'll print nothing, but it's better to print something like below like set_graph_notrace does: #### no functions disabled #### Link: http://lkml.kernel.org/p/1402644246-4649-1-git-send-email-namhyung@kernel.org Reported-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | | | tracing: Improve message of empty set_graph_notrace fileNamhyung Kim2014-07-01
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When there's no entry in set_graph_notrace, it'll print below message #### all functions enabled #### While this is technically correct, it's better to print like below: #### no functions disabled #### Link: http://lkml.kernel.org/p/1402590233-22321-3-git-send-email-namhyung@kernel.org Reported-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | | | tracing: Add ftrace_graph_notrace boot parameterNamhyung Kim2014-07-01
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The ftrace_graph_notrace option is for specifying notrace filter for function graph tracer at boot time. It can be altered after boot using set_graph_notrace file on the debugfs. Link: http://lkml.kernel.org/p/1402590233-22321-2-git-send-email-namhyung@kernel.org Signed-off-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | | | tracing: Convert pr_warning() to pr_warn() in trace_events.cFabian Frederick2014-07-01
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Convert pr_warning to standard pr_warn Define pr_fmt(fmt) fmt to avoid any future default fmt definition Link: http://lkml.kernel.org/p/1402141388-21144-1-git-send-email-fabf@skynet.be Signed-off-by: Fabian Frederick <fabf@skynet.be> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | | | ftrace: Do not copy hash if O_TRUNC is setNamhyung Kim2014-07-01
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When a filter file is open for writing and O_TRUNC is set, there's no need to copy and free the filter entries. Link: http://lkml.kernel.org/p/1402474014-28655-2-git-send-email-namhyung@kernel.org Signed-off-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | | | ftrace: Fix memory leak on failure path in ftrace_allocate_pages()Namhyung Kim2014-07-01
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | As struct ftrace_page is managed in a single linked list, it should free from the start page. Link: http://lkml.kernel.org/p/1402474014-28655-1-git-send-email-namhyung@kernel.org Signed-off-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | | | ftrace: Get rid of obsolete global_start_up variableNamhyung Kim2014-07-01
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | It seems like it's a leftover from commit 4104d326b670 ("ftrace: Remove global function list and call function directly"). As it isn't updated at all, checking its value is meaningless. Let's get rid of it. Link: http://lkml.kernel.org/p/1402584972-17824-1-git-send-email-namhyung@kernel.org Signed-off-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | | | tracing: Add trace_seq_buffer_ptr() helper functionSteven Rostedt (Red Hat)2014-07-01
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There's several locations in the kernel that open code the calculation of the next location in the trace_seq buffer. This is usually done with p->buffer + p->len Instead of having this open coded, supply a helper function in the header to do it for them. This function is called trace_seq_buffer_ptr(). Link: http://lkml.kernel.org/p/20140626220129.452783019@goodmis.org Acked-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | | | tracing: Remove unnecessary null test before debugfs_remove()Fabian Frederick2014-07-01
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This fixes checkpatch warning: "WARNING: debugfs_remove(NULL) is safe this check is probably not required" Link: http://lkml.kernel.org/p/1403802871-8599-1-git-send-email-fabf@skynet.be Signed-off-by: Fabian Frederick <fabf@skynet.be> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | | | tracing: Remove trace_seq_reserve()Steven Rostedt (Red Hat)2014-07-01
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | trace_seq_reserve() has no users in the kernel, it just wastes space. Remove it. Cc: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | | | tracing: Make trace_seq_putmem_hex() more robustSteven Rostedt (Red Hat)2014-07-01
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently trace_seq_putmem_hex() can only take as a parameter a pointer to something that is 8 bytes or less, otherwise it will overflow the buffer. This is protected by a macro that encompasses the call to trace_seq_putmem_hex() that has a BUILD_BUG_ON() for the variable before it is passed in. This is not very robust and if trace_seq_putmem_hex() ever gets used outside that macro it will cause issues. Instead of only being able to produce a hex output of memory that is for a single word, change it to be more robust and allow any size input. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | | | tracing: Clean up trace_seq.cSteven Rostedt (Red Hat)2014-07-01
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | For using trace_seq_*() functions in NMI context, I posted a patch to move it to the lib/ directory. This caused Andrew Morton to take a look at the code. He went through and gave a lot of comments about missing kernel doc, inconsistent types for the save variable, mix match of EXPORT_SYMBOL_GPL() and EXPORT_SYMBOL() as well as missing EXPORT_SYMBOL*()s. There were a few comments about the way variables were being compared (int vs uint). All these were good review comments and should be implemented regardless of if trace_seq.c should be moved to lib/ or not. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | | | tracing: Move the trace_seq_* functions into its own trace_seq.c fileSteven Rostedt (Red Hat)2014-07-01
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The trace_seq_*() functions are a nice utility that allows users to manipulate buffers with printf() like formats. It has its own trace_seq.h header in include/linux and should be in its own file. Being tied with trace_output.c is rather awkward. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | | | ftrace: Simplify ftrace_hash_disable/enable path in ftrace_hash_moveMasami Hiramatsu2014-07-01
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Simplify ftrace_hash_disable/enable path in ftrace_hash_move for hardening the process if the memory allocation failed. Link: http://lkml.kernel.org/p/20140617110442.15167.81076.stgit@kbuild-fedora.novalocal Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | | | ftrace: Add trampolines to enabled_functions debug fileSteven Rostedt (Red Hat)2014-07-01
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The enabled_functions is used to help debug the dynamic function tracing. Adding what trampolines are attached to files is useful for debugging. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | | | ftrace: Optimize function graph to be called directlySteven Rostedt (Red Hat)2014-07-01
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Function graph tracing is a bit different than the function tracers, as it is processed after either the ftrace_caller or ftrace_regs_caller and we only have one place to modify the jump to ftrace_graph_caller, the jump needs to happen after the restore of registeres. The function graph tracer is dependent on the function tracer, where even if the function graph tracing is going on by itself, the save and restore of registers is still done for function tracing regardless of if function tracing is happening, before it calls the function graph code. If there's no function tracing happening, it is possible to just call the function graph tracer directly, and avoid the wasted effort to save and restore regs for function tracing. This requires adding new flags to the dyn_ftrace records: FTRACE_FL_TRAMP FTRACE_FL_TRAMP_EN The first is set if the count for the record is one, and the ftrace_ops associated to that record has its own trampoline. That way the mcount code can call that trampoline directly. In the future, trampolines can be added to arbitrary ftrace_ops, where you can have two or more ftrace_ops registered to ftrace (like kprobes and perf) and if they are not tracing the same functions, then instead of doing a loop to check all registered ftrace_ops against their hashes, just call the ftrace_ops trampoline directly, which would call the registered ftrace_ops function directly. Without this patch perf showed: 0.05% hackbench [kernel.kallsyms] [k] ftrace_caller 0.05% hackbench [kernel.kallsyms] [k] arch_local_irq_save 0.05% hackbench [kernel.kallsyms] [k] native_sched_clock 0.04% hackbench [kernel.kallsyms] [k] __buffer_unlock_commit 0.04% hackbench [kernel.kallsyms] [k] preempt_trace 0.04% hackbench [kernel.kallsyms] [k] prepare_ftrace_return 0.04% hackbench [kernel.kallsyms] [k] __this_cpu_preempt_check 0.04% hackbench [kernel.kallsyms] [k] ftrace_graph_caller See that the ftrace_caller took up more time than the ftrace_graph_caller did. With this patch: 0.05% hackbench [kernel.kallsyms] [k] __buffer_unlock_commit 0.04% hackbench [kernel.kallsyms] [k] call_filter_check_discard 0.04% hackbench [kernel.kallsyms] [k] ftrace_graph_caller 0.04% hackbench [kernel.kallsyms] [k] sched_clock The ftrace_caller is no where to be found and ftrace_graph_caller still takes up the same percentage. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | | | | | | | | | | | | | ftrace: Add ftrace_rec_counter() macro to simplify the codeSteven Rostedt (Red Hat)2014-06-30
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The ftrace dynamic record has a flags element that also has a counter. Instead of hard coding "rec->flags & ~FTRACE_FL_MASK" all over the place. Use a macro instead. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>