[PATCH 27/45] perf/x86: Use get/put_online_cpus_atomic() to prevent CPU offline
From: Srivatsa S. Bhat <hidden>
Date: 2013-06-23 13:47:26
Also in:
linux-arch, linux-pm, lkml, netdev
Subsystem:
performance events subsystem, the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo, Namhyung Kim, Linus Torvalds, Thomas Gleixner, Borislav Petkov, Dave Hansen
The CPU_DYING notifier modifies the per-cpu pointer pmu->box, and this can race with functions such as uncore_pmu_to_box() and uncore_pci_remove() when we remove stop_machine() from the CPU offline path. So protect them using get/put_online_cpus_atomic(). Cc: Peter Zijlstra <redacted> Cc: Paul Mackerras <redacted> Cc: Ingo Molnar <mingo@redhat.com> Cc: Arnaldo Carvalho de Melo <redacted> Cc: Thomas Gleixner <redacted> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: x86@kernel.org Signed-off-by: Srivatsa S. Bhat <redacted> --- arch/x86/kernel/cpu/perf_event_intel_uncore.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/arch/x86/kernel/cpu/perf_event_intel_uncore.c b/arch/x86/kernel/cpu/perf_event_intel_uncore.c
index 9dd9975..7c2a064 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_uncore.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_uncore.c@@ -1,3 +1,4 @@ +#include <linux/cpu.h> #include "perf_event_intel_uncore.h" static struct intel_uncore_type *empty_uncore[] = { NULL, };
@@ -2630,6 +2631,7 @@ uncore_pmu_to_box(struct intel_uncore_pmu *pmu, int cpu) if (box) return box; + get_online_cpus_atomic(); raw_spin_lock(&uncore_box_lock); list_for_each_entry(box, &pmu->box_list, list) { if (box->phys_id == topology_physical_package_id(cpu)) {
@@ -2639,6 +2641,7 @@ uncore_pmu_to_box(struct intel_uncore_pmu *pmu, int cpu) } } raw_spin_unlock(&uncore_box_lock); + put_online_cpus_atomic(); return *per_cpu_ptr(pmu->box, cpu); }
@@ -3229,6 +3232,7 @@ static void uncore_pci_remove(struct pci_dev *pdev) list_del(&box->list); raw_spin_unlock(&uncore_box_lock); + get_online_cpus_atomic(); for_each_possible_cpu(cpu) { if (*per_cpu_ptr(pmu->box, cpu) == box) { *per_cpu_ptr(pmu->box, cpu) = NULL;
@@ -3237,6 +3241,8 @@ static void uncore_pci_remove(struct pci_dev *pdev) } WARN_ON_ONCE(atomic_read(&box->refcnt) != 1); + put_online_cpus_atomic(); + kfree(box); }