Commit 1239cab7 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Luo Gengkun
Browse files

perf/core: Fix pmus_lock vs. pmus_srcu ordering 

stable inclusion
from stable-v6.6.83
commit 7c823e4c30d6fdc16089e13924260086eaea76be
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/IBXQNU

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7c823e4c30d6fdc16089e13924260086eaea76be



--------------------------------

[ Upstream commit 2565e42539b120b81a68a58da961ce5d1e34eac8 ]

Commit a63fbed7 ("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: a63fbed7 ("perf/tracing/cpuhotplug: Fix locking order")
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20241104135517.679556858@infradead.org


Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
Signed-off-by: default avatarLuo Gengkun <luogengkun2@huawei.com>
parent 75db7d4f

kernel/events/core.c

+2 −2
Original line number Diff line number Diff line
@@ -11670,6 +11670,8 @@ 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
@@ -11679,7 +11681,6 @@ 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);
@@ -11687,7 +11688,6 @@ 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);