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perf/core: Fix pmus_lock vs. pmus_srcu ordering

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[ Upstream commit 2565e42539b120b81a68a58da961ce5d1e34eac8 ]

Commit a63fbed776 ("perf/tracing/cpuhotplug: Fix locking order")
placed pmus_lock inside pmus_srcu, this makes perf_pmu_unregister()
trip lockdep.

Move the locking about such that only pmu_idr and pmus (list) are
modified while holding pmus_lock. This avoids doing synchronize_srcu()
while holding pmus_lock and all is well again.

Fixes: a63fbed776 ("perf/tracing/cpuhotplug: Fix locking order")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20241104135517.679556858@infradead.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Peter Zijlstra
2024-11-04 14:39:11 +01:00
committed by Greg Kroah-Hartman
parent 90d302619e
commit 7c823e4c30
1 changed files with 2 additions and 2 deletions
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4
kernel/events/core.c
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@@ -11660,6 +11660,8 @@ void perf_pmu_unregister(struct pmu *pmu)
{
mutex_lock(&pmus_lock);
list_del_rcu(&pmu->entry);
idr_remove(&pmu_idr, pmu->type);
mutex_unlock(&pmus_lock);
/*
* We dereference the pmu list under both SRCU and regular RCU, so
@@ -11669,7 +11671,6 @@ void perf_pmu_unregister(struct pmu *pmu)
synchronize_rcu();
free_percpu(pmu->pmu_disable_count);
idr_remove(&pmu_idr, pmu->type);
if (pmu_bus_running && pmu->dev && pmu->dev != PMU_NULL_DEV) {
if (pmu->nr_addr_filters)
device_remove_file(pmu->dev, &dev_attr_nr_addr_filters);
@@ -11677,7 +11678,6 @@ void perf_pmu_unregister(struct pmu *pmu)
put_device(pmu->dev);
}
free_pmu_context(pmu);
mutex_unlock(&pmus_lock);
}
EXPORT_SYMBOL_GPL(perf_pmu_unregister);