The following commit has been merged into the perf/core branch of tip: Commit-ID: 2565e42539b120b81a68a58da961ce5d1e34eac8 Gitweb: https://git.kernel.org/tip/2565e42539b120b81a68a58da961ce5d1e34eac8 Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx> AuthorDate: Mon, 04 Nov 2024 14:39:11 +01:00 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitterDate: Sat, 01 Mar 2025 19:38:42 +01:00 perf/core: Fix pmus_lock vs. pmus_srcu ordering 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@xxxxxxxxxxxxx> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Link: https://lore.kernel.org/r/20241104135517.679556858@xxxxxxxxxxxxx --- 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 6364319..11793d6 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -11939,6 +11939,8 @@ 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 @@ -11948,7 +11950,6 @@ 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); @@ -11956,7 +11957,6 @@ 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);
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