Commit-ID: 0933840acf7b65d6d30a5b6089d882afea57aca3 Gitweb: http://git.kernel.org/tip/0933840acf7b65d6d30a5b6089d882afea57aca3 Author: Jiri Olsa <jo...@redhat.com> AuthorDate: Thu, 20 Oct 2016 13:10:11 +0200 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Fri, 28 Oct 2016 11:06:25 +0200
perf/core: Protect PMU device removal with a 'pmu_bus_running' check, to fix CONFIG_DEBUG_TEST_DRIVER_REMOVE=y kernel panic CAI Qian reported a crash in the PMU uncore device removal code, enabled by the CONFIG_DEBUG_TEST_DRIVER_REMOVE=y option: https://marc.info/?l=linux-kernel&m=147688837328451 The reason for the crash is that perf_pmu_unregister() tries to remove a PMU device which is not added at this point. We add PMU devices only after pmu_bus is registered, which happens in the perf_event_sysfs_init() call and sets the 'pmu_bus_running' flag. The fix is to get the 'pmu_bus_running' flag state at the point the PMU is taken out of the PMU list and remove the device later only if it's set. Reported-by: CAI Qian <caiq...@redhat.com> Tested-by: CAI Qian <caiq...@redhat.com> Signed-off-by: Jiri Olsa <jo...@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> Cc: Alexander Shishkin <alexander.shish...@linux.intel.com> Cc: Arnaldo Carvalho de Melo <a...@redhat.com> Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org> Cc: Jiri Olsa <jo...@redhat.com> Cc: Kan Liang <kan.li...@intel.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Rob Herring <r...@kernel.org> Cc: Thomas Gleixner <t...@linutronix.de> Link: http://lkml.kernel.org/r/20161020111011.GA13361@krava Signed-off-by: Ingo Molnar <mi...@kernel.org> --- kernel/events/core.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index c6e47e9..a5d2e62 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -8855,7 +8855,10 @@ 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); @@ -8869,10 +8872,12 @@ 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 (pmu->nr_addr_filters) - device_remove_file(pmu->dev, &dev_attr_nr_addr_filters); - device_del(pmu->dev); - put_device(pmu->dev); + if (remove_device) { + 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); } EXPORT_SYMBOL_GPL(perf_pmu_unregister);
