From 2840dadf0dde92638d13b97998026c5fcddbdceb Mon Sep 17 00:00:00 2001 From: Alexandre Ghiti Date: Mon, 26 Aug 2024 18:52:10 +0200 Subject: [PATCH] drivers: perf: Fix smp_processor_id() use in preemptible code As reported in [1], the use of smp_processor_id() in pmu_sbi_device_probe() must be protected by disabling the preemption, so simple use get_cpu()/put_cpu() instead. Reported-by: Nam Cao Closes: https://lore.kernel.org/linux-riscv/20240820074925.ReMKUPP3@linutronix.de/ [1] Signed-off-by: Alexandre Ghiti Reviewed-by: Anup Patel Tested-by: Nam Cao Fixes: a8625217a054 ("drivers/perf: riscv: Implement SBI PMU snapshot function") Reported-by: Andrea Parri Tested-by: Andrea Parri Link: https://lore.kernel.org/r/20240826165210.124696-1-alexghiti@rivosinc.com Signed-off-by: Palmer Dabbelt --- drivers/perf/riscv_pmu_sbi.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/perf/riscv_pmu_sbi.c b/drivers/perf/riscv_pmu_sbi.c index 31a17a56eb3b..25b1b699b3e2 100644 --- a/drivers/perf/riscv_pmu_sbi.c +++ b/drivers/perf/riscv_pmu_sbi.c @@ -1373,11 +1373,15 @@ static int pmu_sbi_device_probe(struct platform_device *pdev) /* SBI PMU Snapsphot is only available in SBI v2.0 */ if (sbi_v2_available) { + int cpu; + ret = pmu_sbi_snapshot_alloc(pmu); if (ret) goto out_unregister; - ret = pmu_sbi_snapshot_setup(pmu, smp_processor_id()); + cpu = get_cpu(); + + ret = pmu_sbi_snapshot_setup(pmu, cpu); if (ret) { /* Snapshot is an optional feature. Continue if not available */ pmu_sbi_snapshot_free(pmu); @@ -1391,6 +1395,7 @@ static int pmu_sbi_device_probe(struct platform_device *pdev) */ static_branch_enable(&sbi_pmu_snapshot_available); } + put_cpu(); } register_sysctl("kernel", sbi_pmu_sysctl_table);