diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/events/core.c | 7 | ||||
| -rw-r--r-- | kernel/events/internal.h | 2 | ||||
| -rw-r--r-- | kernel/exit.c | 5 | ||||
| -rw-r--r-- | kernel/reboot.c | 28 | ||||
| -rw-r--r-- | kernel/time/timer.c | 7 | ||||
| -rw-r--r-- | kernel/trace/ring_buffer.c | 54 |
6 files changed, 67 insertions, 36 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index ebedf5a76f35..3e1a35b7a225 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -4669,11 +4669,11 @@ static void perf_mmap_open(struct vm_area_struct *vma) static void perf_mmap_close(struct vm_area_struct *vma) { struct perf_event *event = vma->vm_file->private_data; - struct ring_buffer *rb = ring_buffer_get(event); struct user_struct *mmap_user = rb->mmap_user; int mmap_locked = rb->mmap_locked; unsigned long size = perf_data_size(rb); + bool detach_rest = false; if (event->pmu->event_unmapped) event->pmu->event_unmapped(event); @@ -4692,7 +4692,8 @@ static void perf_mmap_close(struct vm_area_struct *vma) mutex_unlock(&event->mmap_mutex); } - atomic_dec(&rb->mmap_count); + if (atomic_dec_and_test(&rb->mmap_count)) + detach_rest = true; if (!atomic_dec_and_mutex_lock(&event->mmap_count, &event->mmap_mutex)) goto out_put; @@ -4701,7 +4702,7 @@ static void perf_mmap_close(struct vm_area_struct *vma) mutex_unlock(&event->mmap_mutex); /* If there's still other mmap()s of this buffer, we're done. */ - if (atomic_read(&rb->mmap_count)) + if (!detach_rest) goto out_put; /* diff --git a/kernel/events/internal.h b/kernel/events/internal.h index 2bbad9c1274c..8baa3121e7a6 100644 --- a/kernel/events/internal.h +++ b/kernel/events/internal.h @@ -193,7 +193,7 @@ static inline int get_recursion_context(int *recursion) rctx = 3; else if (in_irq()) rctx = 2; - else if (in_softirq()) + else if (in_serving_softirq()) rctx = 1; else rctx = 0; diff --git a/kernel/exit.c b/kernel/exit.c index 6e8ab67325a7..bf2c26e4ab42 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -411,7 +411,10 @@ static void exit_mm(struct task_struct *tsk) up_read(&mm->mmap_sem); self.task = tsk; - self.next = xchg(&core_state->dumper.next, &self); + if (self.task->flags & PF_SIGNALED) + self.next = xchg(&core_state->dumper.next, &self); + else + self.task = NULL; /* * Implies mb(), the result of xchg() must be visible * to core_state->dumper. diff --git a/kernel/reboot.c b/kernel/reboot.c index bd30a973fe94..2946ed1d99d4 100644 --- a/kernel/reboot.c +++ b/kernel/reboot.c @@ -512,22 +512,22 @@ static int __init reboot_setup(char *str) break; case 's': - { - int rc; - - if (isdigit(*(str+1))) { - rc = kstrtoint(str+1, 0, &reboot_cpu); - if (rc) - return rc; - } else if (str[1] == 'm' && str[2] == 'p' && - isdigit(*(str+3))) { - rc = kstrtoint(str+3, 0, &reboot_cpu); - if (rc) - return rc; - } else + if (isdigit(*(str+1))) + reboot_cpu = simple_strtoul(str+1, NULL, 0); + else if (str[1] == 'm' && str[2] == 'p' && + isdigit(*(str+3))) + reboot_cpu = simple_strtoul(str+3, NULL, 0); + else reboot_mode = REBOOT_SOFT; + if (reboot_cpu >= num_possible_cpus()) { + pr_err("Ignoring the CPU number in reboot= option. " + "CPU %d exceeds possible cpu number %d\n", + reboot_cpu, num_possible_cpus()); + reboot_cpu = 0; + break; + } break; - } + case 'g': reboot_mode = REBOOT_GPIO; break; diff --git a/kernel/time/timer.c b/kernel/time/timer.c index 56ac932476f1..8e9e4b86f23e 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -1432,13 +1432,6 @@ void update_process_times(int user_tick) #endif scheduler_tick(); run_posix_cpu_timers(p); - - /* The current CPU might make use of net randoms without receiving IRQs - * to renew them often enough. Let's update the net_rand_state from a - * non-constant value that's not affine to the number of calls to make - * sure it's updated when there's some activity (we don't care in idle). - */ - this_cpu_add(net_rand_state.s1, rol32(jiffies, 24) + user_tick); } /* diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 1c1ecc1d49ad..547a3a5ac57b 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -416,14 +416,16 @@ struct rb_event_info { /* * Used for which event context the event is in. - * NMI = 0 - * IRQ = 1 - * SOFTIRQ = 2 - * NORMAL = 3 + * TRANSITION = 0 + * NMI = 1 + * IRQ = 2 + * SOFTIRQ = 3 + * NORMAL = 4 * * See trace_recursive_lock() comment below for more details. */ enum { + RB_CTX_TRANSITION, RB_CTX_NMI, RB_CTX_IRQ, RB_CTX_SOFTIRQ, @@ -2585,10 +2587,10 @@ rb_wakeups(struct ring_buffer *buffer, struct ring_buffer_per_cpu *cpu_buffer) * a bit of overhead in something as critical as function tracing, * we use a bitmask trick. * - * bit 0 = NMI context - * bit 1 = IRQ context - * bit 2 = SoftIRQ context - * bit 3 = normal context. + * bit 1 = NMI context + * bit 2 = IRQ context + * bit 3 = SoftIRQ context + * bit 4 = normal context. * * This works because this is the order of contexts that can * preempt other contexts. A SoftIRQ never preempts an IRQ @@ -2611,6 +2613,30 @@ rb_wakeups(struct ring_buffer *buffer, struct ring_buffer_per_cpu *cpu_buffer) * The least significant bit can be cleared this way, and it * just so happens that it is the same bit corresponding to * the current context. + * + * Now the TRANSITION bit breaks the above slightly. The TRANSITION bit + * is set when a recursion is detected at the current context, and if + * the TRANSITION bit is already set, it will fail the recursion. + * This is needed because there's a lag between the changing of + * interrupt context and updating the preempt count. In this case, + * a false positive will be found. To handle this, one extra recursion + * is allowed, and this is done by the TRANSITION bit. If the TRANSITION + * bit is already set, then it is considered a recursion and the function + * ends. Otherwise, the TRANSITION bit is set, and that bit is returned. + * + * On the trace_recursive_unlock(), the TRANSITION bit will be the first + * to be cleared. Even if it wasn't the context that set it. That is, + * if an interrupt comes in while NORMAL bit is set and the ring buffer + * is called before preempt_count() is updated, since the check will + * be on the NORMAL bit, the TRANSITION bit will then be set. If an + * NMI then comes in, it will set the NMI bit, but when the NMI code + * does the trace_recursive_unlock() it will clear the TRANSTION bit + * and leave the NMI bit set. But this is fine, because the interrupt + * code that set the TRANSITION bit will then clear the NMI bit when it + * calls trace_recursive_unlock(). If another NMI comes in, it will + * set the TRANSITION bit and continue. + * + * Note: The TRANSITION bit only handles a single transition between context. */ static __always_inline int @@ -2629,8 +2655,16 @@ trace_recursive_lock(struct ring_buffer_per_cpu *cpu_buffer) } else bit = RB_CTX_NORMAL; - if (unlikely(val & (1 << bit))) - return 1; + if (unlikely(val & (1 << bit))) { + /* + * It is possible that this was called by transitioning + * between interrupt context, and preempt_count() has not + * been updated yet. In this case, use the TRANSITION bit. + */ + bit = RB_CTX_TRANSITION; + if (val & (1 << bit)) + return 1; + } val |= (1 << bit); cpu_buffer->current_context = val; |