6.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Peter Zijlstra peterz@infradead.org
[ Upstream commit 2565e42539b120b81a68a58da961ce5d1e34eac8 ]
Commit a63fbed776c7 ("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: a63fbed776c7 ("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 --- kernel/events/core.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c index a0e1d2124727e..5fff74c736063 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -11846,6 +11846,8 @@ 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 @@ -11855,7 +11857,6 @@ 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); @@ -11863,7 +11864,6 @@ 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);