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| author | Ingo Molnar <mingo@elte.hu> | 2009-05-29 11:25:09 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-05-29 14:28:36 +0200 |
| commit | 3f4dee227348daac32f36daad9a91059efd0723e (patch) | |
| tree | 9aa0311f0c4f961a2c2cab1d2fbb0994cff1b6d9 /kernel | |
| parent | ad3a37de81c45f6c20d410ece86004b98f7b6d84 (diff) | |
| download | linux-3f4dee227348daac32f36daad9a91059efd0723e.tar.gz linux-3f4dee227348daac32f36daad9a91059efd0723e.tar.bz2 linux-3f4dee227348daac32f36daad9a91059efd0723e.zip | |
perf_counter: Fix cpuctx->task_ctx races
Peter noticed that we are sometimes reading cpuctx->task_ctx with
interrupts enabled.
Noticed-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/perf_counter.c | 28 |
1 files changed, 20 insertions, 8 deletions
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c index db843f812a60..eb346048f00f 100644 --- a/kernel/perf_counter.c +++ b/kernel/perf_counter.c @@ -234,15 +234,18 @@ static void __perf_counter_remove_from_context(void *info) struct perf_counter_context *ctx = counter->ctx; unsigned long flags; + local_irq_save(flags); /* * If this is a task context, we need to check whether it is * the current task context of this cpu. If not it has been * scheduled out before the smp call arrived. */ - if (ctx->task && cpuctx->task_ctx != ctx) + if (ctx->task && cpuctx->task_ctx != ctx) { + local_irq_restore(flags); return; + } - spin_lock_irqsave(&ctx->lock, flags); + spin_lock(&ctx->lock); /* * Protect the list operation against NMI by disabling the * counters on a global level. @@ -382,14 +385,17 @@ static void __perf_counter_disable(void *info) struct perf_counter_context *ctx = counter->ctx; unsigned long flags; + local_irq_save(flags); /* * If this is a per-task counter, need to check whether this * counter's task is the current task on this cpu. */ - if (ctx->task && cpuctx->task_ctx != ctx) + if (ctx->task && cpuctx->task_ctx != ctx) { + local_irq_restore(flags); return; + } - spin_lock_irqsave(&ctx->lock, flags); + spin_lock(&ctx->lock); /* * If the counter is on, turn it off. @@ -615,6 +621,7 @@ static void __perf_install_in_context(void *info) unsigned long flags; int err; + local_irq_save(flags); /* * If this is a task context, we need to check whether it is * the current task context of this cpu. If not it has been @@ -623,12 +630,14 @@ static void __perf_install_in_context(void *info) * on this cpu because it had no counters. */ if (ctx->task && cpuctx->task_ctx != ctx) { - if (cpuctx->task_ctx || ctx->task != current) + if (cpuctx->task_ctx || ctx->task != current) { + local_irq_restore(flags); return; + } cpuctx->task_ctx = ctx; } - spin_lock_irqsave(&ctx->lock, flags); + spin_lock(&ctx->lock); ctx->is_active = 1; update_context_time(ctx); @@ -745,17 +754,20 @@ static void __perf_counter_enable(void *info) unsigned long flags; int err; + local_irq_save(flags); /* * If this is a per-task counter, need to check whether this * counter's task is the current task on this cpu. */ if (ctx->task && cpuctx->task_ctx != ctx) { - if (cpuctx->task_ctx || ctx->task != current) + if (cpuctx->task_ctx || ctx->task != current) { + local_irq_restore(flags); return; + } cpuctx->task_ctx = ctx; } - spin_lock_irqsave(&ctx->lock, flags); + spin_lock(&ctx->lock); ctx->is_active = 1; update_context_time(ctx); |