Return-Path: From: Sasha Levin To: stable@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Peter Zijlstra , Alexander Shishkin , Arnaldo Carvalho de Melo , Jiri Olsa , Linus Torvalds , Stephane Eranian , Thomas Gleixner , Vince Weaver , Ingo Molnar , Sasha Levin Subject: [PATCH AUTOSEL 4.18 065/100] perf/core: Fix perf_pmu_unregister() locking Date: Tue, 16 Oct 2018 00:11:46 -0400 Message-Id: <20181016041221.135528-65-sashal@kernel.org> In-Reply-To: <20181016041221.135528-1-sashal@kernel.org> References: <20181016041221.135528-1-sashal@kernel.org> List-ID: From: Peter Zijlstra [ Upstream commit a9f9772114c8b07ae75bcb3654bd017461248095 ] 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) Cc: Alexander Shishkin Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Gleixner Cc: Vince Weaver Fixes: 2e80a82a49c4 ("perf: Dynamic pmu types") Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin --- kernel/events/core.c | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index ae22d93701db..b1ed5e99d9c6 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -9436,9 +9436,7 @@ static void free_pmu_context(struct pmu *pmu) if (pmu->task_ctx_nr > perf_invalid_context) return; - mutex_lock(&pmus_lock); free_percpu(pmu->pmu_cpu_context); - mutex_unlock(&pmus_lock); } /* @@ -9694,12 +9692,8 @@ 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 @@ -9711,13 +9705,14 @@ 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) { if (pmu->nr_addr_filters) device_remove_file(pmu->dev, &dev_attr_nr_addr_filters); device_del(pmu->dev); put_device(pmu->dev); } free_pmu_context(pmu); + mutex_unlock(&pmus_lock); } EXPORT_SYMBOL_GPL(perf_pmu_unregister); -- 2.17.1