diff options
| author | Vikram Mulukutla <markivx@codeaurora.org> | 2017-07-06 10:05:52 -0700 |
|---|---|---|
| committer | Georg Veichtlbauer <georg@vware.at> | 2023-07-26 21:01:08 +0200 |
| commit | 9e9dec3e818e5d10b81a5ccc167af54612cac21d (patch) | |
| tree | 7dd50b7f021805821ecc1c8ab95982685c8942f9 /kernel | |
| parent | 821cf3a1a8476001f02a27771dcd27ef8b913feb (diff) | |
cpufreq: schedutil: Fix sugov_start versus sugov_update_shared race
With a shared policy in place, when one of the CPUs in the policy is
hotplugged out and then brought back online, sugov_stop and
sugov_start are called in order.
sugov_stop removes utilization hooks for each CPU in the policy and
does nothing else in the for_each_cpu loop. sugov_start on the other
hand iterates through the CPUs in the policy and re-initializes the
per-cpu structure _and_ adds the utilization hook. This implies that
the scheduler is allowed to invoke a CPU's utilization update hook
when the rest of the per-cpu structures have yet to be re-inited.
Apart from some strange values in tracepoints this doesn't cause a
problem, but if we do end up accessing a pointer from the per-cpu
sugov_cpu structure somewhere in the sugov_update_shared path,
we will likely see crashes since the memset for another CPU in the
policy is free to race with sugov_update_shared from the CPU that is
ready to go. So let's fix this now to first init all per-cpu
structures, and then add the per-cpu utilization update hooks all at
once.
Change-Id: I399e0e159b3db3ae3258843c9231f92312fe18ef
Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched/cpufreq_schedutil.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c index f4c7e6f81460..afb63ce7b084 100644 --- a/kernel/sched/cpufreq_schedutil.c +++ b/kernel/sched/cpufreq_schedutil.c @@ -831,6 +831,11 @@ static int sugov_start(struct cpufreq_policy *policy) sg_cpu->sg_policy = sg_policy; sg_cpu->flags = SCHED_CPUFREQ_DL; sg_cpu->iowait_boost_max = policy->cpuinfo.max_freq; + } + + for_each_cpu(cpu, policy->cpus) { + struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu); + cpufreq_add_update_util_hook(cpu, &sg_cpu->update_util, policy_is_shared(policy) ? sugov_update_shared : |