From 22cc4ccf63e10e361531bf61e6e6c96c53a2f665 Mon Sep 17 00:00:00 2001 From: "Yan, Zheng" Date: Tue, 16 Apr 2013 19:51:05 +0800 Subject: [PATCH] perf/x86: Avoid kfree() in CPU_{STARTING,DYING} On -rt kfree() can schedule, but CPU_{STARTING,DYING} should be atomic. So use a list to defer kfree until CPU_{ONLINE,DEAD}. Signed-off-by: Yan, Zheng Acked-by: Peter Zijlstra Cc: peterz@infradead.org Cc: eranian@google.com Cc: ak@linux.intel.com Link: http://lkml.kernel.org/r/1366113067-3262-2-git-send-email-zheng.z.yan@intel.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/perf_event_intel_uncore.c | 28 +++++++++++++++++-- 1 file changed, 25 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_event_intel_uncore.c b/arch/x86/kernel/cpu/perf_event_intel_uncore.c index 75da9e18b128..50d4a1c58106 100644 --- a/arch/x86/kernel/cpu/perf_event_intel_uncore.c +++ b/arch/x86/kernel/cpu/perf_event_intel_uncore.c @@ -2622,6 +2622,21 @@ static void __init uncore_pci_exit(void) } } +/* CPU hot plug/unplug are serialized by cpu_add_remove_lock mutex */ +static LIST_HEAD(boxes_to_free); + +static void __cpuinit uncore_kfree_boxes(void) +{ + struct intel_uncore_box *box; + + while (!list_empty(&boxes_to_free)) { + box = list_entry(boxes_to_free.next, + struct intel_uncore_box, list); + list_del(&box->list); + kfree(box); + } +} + static void __cpuinit uncore_cpu_dying(int cpu) { struct intel_uncore_type *type; @@ -2636,7 +2651,7 @@ static void __cpuinit uncore_cpu_dying(int cpu) box = *per_cpu_ptr(pmu->box, cpu); *per_cpu_ptr(pmu->box, cpu) = NULL; if (box && atomic_dec_and_test(&box->refcnt)) - kfree(box); + list_add(&box->list, &boxes_to_free); } } } @@ -2666,8 +2681,11 @@ static int __cpuinit uncore_cpu_starting(int cpu) if (exist && exist->phys_id == phys_id) { atomic_inc(&exist->refcnt); *per_cpu_ptr(pmu->box, cpu) = exist; - kfree(box); - box = NULL; + if (box) { + list_add(&box->list, + &boxes_to_free); + box = NULL; + } break; } } @@ -2806,6 +2824,10 @@ static int case CPU_DYING: uncore_cpu_dying(cpu); break; + case CPU_ONLINE: + case CPU_DEAD: + uncore_kfree_boxes(); + break; default: break; }