3.16.62-rc1 review patch. If anyone has any objections, please let me know.
------------------ From: Peter Zijlstra <[email protected]> commit a9f9772114c8b07ae75bcb3654bd017461248095 upstream. When we unregister a PMU, we fail to serialize the @pmu_idr properly. Fix that by doing the entire thing under pmu_lock. Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Cc: Alexander Shishkin <[email protected]> Cc: Arnaldo Carvalho de Melo <[email protected]> Cc: Jiri Olsa <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Stephane Eranian <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Vince Weaver <[email protected]> Fixes: 2e80a82a49c4 ("perf: Dynamic pmu types") Signed-off-by: Ingo Molnar <[email protected]> [bwh: Backported to 3.16: - Also remove "out" label in free_pmu_context() - Adjust context] Signed-off-by: Ben Hutchings <[email protected]> --- --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6705,20 +6705,17 @@ static void free_pmu_context(struct pmu { struct pmu *i; - mutex_lock(&pmus_lock); /* * Like a real lame refcount. */ list_for_each_entry(i, &pmus, entry) { if (i->pmu_cpu_context == pmu->pmu_cpu_context) { update_pmu_context(i, pmu); - goto out; + return; } } free_percpu(pmu->pmu_cpu_context); -out: - mutex_unlock(&pmus_lock); } static struct idr pmu_idr; @@ -6930,12 +6927,8 @@ EXPORT_SYMBOL_GPL(perf_pmu_register); void perf_pmu_unregister(struct pmu *pmu) { - int remove_device; - mutex_lock(&pmus_lock); - remove_device = pmu_bus_running; list_del_rcu(&pmu->entry); - mutex_unlock(&pmus_lock); /* * We dereference the pmu list under both SRCU and regular RCU, so @@ -6947,11 +6940,12 @@ void perf_pmu_unregister(struct pmu *pmu free_percpu(pmu->pmu_disable_count); if (pmu->type >= PERF_TYPE_MAX) idr_remove(&pmu_idr, pmu->type); - if (remove_device) { + if (pmu_bus_running) { device_del(pmu->dev); put_device(pmu->dev); } free_pmu_context(pmu); + mutex_unlock(&pmus_lock); } EXPORT_SYMBOL_GPL(perf_pmu_unregister);
