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| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2010-09-16 19:17:24 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2010-09-21 13:55:44 +0200 |
| commit | 41945f6ccf1e86f87fddf6b32db9cf431c05fb54 (patch) | |
| tree | cf64d47bfff06ff4560efcaa23a067fa99db34dd /kernel | |
| parent | 8b8e2ec1eeca7f6941bc81cefc9663018d6ceb57 (diff) | |
| download | linux-41945f6ccf1e86f87fddf6b32db9cf431c05fb54.tar.gz linux-41945f6ccf1e86f87fddf6b32db9cf431c05fb54.tar.bz2 linux-41945f6ccf1e86f87fddf6b32db9cf431c05fb54.zip | |
perf: Avoid RCU vs preemption assumptions
The per-pmu per-cpu context patch converted things from
get_cpu_var() to this_cpu_ptr(), but that only works if
rcu_read_lock() actually disables preemption, and since
there is no such guarantee, we need to fix that.
Use the newly introduced {get,put}_cpu_ptr().
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Tejun Heo <tj@kernel.org>
LKML-Reference: <20100917093009.308453028@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/perf_event.c | 18 |
1 files changed, 12 insertions, 6 deletions
diff --git a/kernel/perf_event.c b/kernel/perf_event.c index baae1367e945..c16158c77dfd 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -3836,18 +3836,20 @@ static void perf_event_task_event(struct perf_task_event *task_event) rcu_read_lock(); list_for_each_entry_rcu(pmu, &pmus, entry) { - cpuctx = this_cpu_ptr(pmu->pmu_cpu_context); + cpuctx = get_cpu_ptr(pmu->pmu_cpu_context); perf_event_task_ctx(&cpuctx->ctx, task_event); ctx = task_event->task_ctx; if (!ctx) { ctxn = pmu->task_ctx_nr; if (ctxn < 0) - continue; + goto next; ctx = rcu_dereference(current->perf_event_ctxp[ctxn]); } if (ctx) perf_event_task_ctx(ctx, task_event); +next: + put_cpu_ptr(pmu->pmu_cpu_context); } rcu_read_unlock(); } @@ -3969,16 +3971,18 @@ static void perf_event_comm_event(struct perf_comm_event *comm_event) rcu_read_lock(); list_for_each_entry_rcu(pmu, &pmus, entry) { - cpuctx = this_cpu_ptr(pmu->pmu_cpu_context); + cpuctx = get_cpu_ptr(pmu->pmu_cpu_context); perf_event_comm_ctx(&cpuctx->ctx, comm_event); ctxn = pmu->task_ctx_nr; if (ctxn < 0) - continue; + goto next; ctx = rcu_dereference(current->perf_event_ctxp[ctxn]); if (ctx) perf_event_comm_ctx(ctx, comm_event); +next: + put_cpu_ptr(pmu->pmu_cpu_context); } rcu_read_unlock(); } @@ -4152,19 +4156,21 @@ got_name: rcu_read_lock(); list_for_each_entry_rcu(pmu, &pmus, entry) { - cpuctx = this_cpu_ptr(pmu->pmu_cpu_context); + cpuctx = get_cpu_ptr(pmu->pmu_cpu_context); perf_event_mmap_ctx(&cpuctx->ctx, mmap_event, vma->vm_flags & VM_EXEC); ctxn = pmu->task_ctx_nr; if (ctxn < 0) - continue; + goto next; ctx = rcu_dereference(current->perf_event_ctxp[ctxn]); if (ctx) { perf_event_mmap_ctx(ctx, mmap_event, vma->vm_flags & VM_EXEC); } +next: + put_cpu_ptr(pmu->pmu_cpu_context); } rcu_read_unlock(); |