Messages in this thread Patch in this message | | | From | Robin Murphy <> | Subject | [PATCH 5/5] perf/arm_dsu: Fix CPU hotplug races | Date | Mon, 4 Feb 2019 17:09:08 +0000 |
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Like other system PMUs which associate themselves with an arbitrary CPU for housekeeping purposes, arm_dsu has a race between registering the hotplug notifier and registering the PMU device, such that the hotplug niotifier can potentially fire and attempt to migrate the PMU context before the latter is valid. This is easily resolved by inhibiting hotplug until both the notifier and PMU device are successfully set up.
For the same reason, also suppress any synchronous notifier calls in the cleanup path if PMU registration fails.
Signed-off-by: Robin Murphy <robin.murphy@arm.com> --- drivers/perf/arm_dsu_pmu.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/drivers/perf/arm_dsu_pmu.c b/drivers/perf/arm_dsu_pmu.c index 660cb8ac886a..cfaca06b964a 100644 --- a/drivers/perf/arm_dsu_pmu.c +++ b/drivers/perf/arm_dsu_pmu.c @@ -717,7 +717,8 @@ static int dsu_pmu_device_probe(struct platform_device *pdev) dsu_pmu->irq = irq; platform_set_drvdata(pdev, dsu_pmu); - rc = cpuhp_state_add_instance(dsu_pmu_cpuhp_state, + cpus_read_lock(); + rc = cpuhp_state_add_instance_cpuslocked(dsu_pmu_cpuhp_state, &dsu_pmu->cpuhp_node); if (rc) return rc; @@ -738,9 +739,10 @@ static int dsu_pmu_device_probe(struct platform_device *pdev) }; rc = perf_pmu_register(&dsu_pmu->pmu, name, -1); + cpus_read_unlock(); if (rc) { - cpuhp_state_remove_instance(dsu_pmu_cpuhp_state, - &dsu_pmu->cpuhp_node); + cpuhp_state_remove_instance_nocalls(dsu_pmu_cpuhp_state, + &dsu_pmu->cpuhp_node); irq_set_affinity_hint(dsu_pmu->irq, NULL); } -- 2.20.1.dirty
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