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Merge branch 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

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* 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  perf: Fix the software context switch counter
  perf, x86: Fixup Kconfig deps
  x86, perf, nmi: Disable perf if counters are not accessible
  perf: Fix inherit vs. context rotation bug
This commit is contained in:
Linus Torvalds 2010-11-28 12:25:02 -08:00
commit a9e40a2493
4 changed files with 57 additions and 19 deletions
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24
kernel/perf_event.c
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@ -1287,8 +1287,6 @@ void __perf_event_task_sched_out(struct task_struct *task,
{
int ctxn;
perf_sw_event(PERF_COUNT_SW_CONTEXT_SWITCHES, 1, 1, NULL, 0);
for_each_task_context_nr(ctxn)
perf_event_context_sched_out(task, ctxn, next);
}
@ -1622,8 +1620,12 @@ static void rotate_ctx(struct perf_event_context *ctx)
{
raw_spin_lock(&ctx->lock);
/* Rotate the first entry last of non-pinned groups */
list_rotate_left(&ctx->flexible_groups);
/*
* Rotate the first entry last of non-pinned groups. Rotation might be
* disabled by the inheritance code.
*/
if (!ctx->rotate_disable)
list_rotate_left(&ctx->flexible_groups);
raw_spin_unlock(&ctx->lock);
}
@ -6162,6 +6164,7 @@ int perf_event_init_context(struct task_struct *child, int ctxn)
struct perf_event *event;
struct task_struct *parent = current;
int inherited_all = 1;
unsigned long flags;
int ret = 0;
child->perf_event_ctxp[ctxn] = NULL;
@ -6202,6 +6205,15 @@ int perf_event_init_context(struct task_struct *child, int ctxn)
break;
}
/*
* We can't hold ctx->lock when iterating the ->flexible_group list due
* to allocations, but we need to prevent rotation because
* rotate_ctx() will change the list from interrupt context.
*/
raw_spin_lock_irqsave(&parent_ctx->lock, flags);
parent_ctx->rotate_disable = 1;
raw_spin_unlock_irqrestore(&parent_ctx->lock, flags);
list_for_each_entry(event, &parent_ctx->flexible_groups, group_entry) {
ret = inherit_task_group(event, parent, parent_ctx,
child, ctxn, &inherited_all);
@ -6209,6 +6221,10 @@ int perf_event_init_context(struct task_struct *child, int ctxn)
break;
}
raw_spin_lock_irqsave(&parent_ctx->lock, flags);
parent_ctx->rotate_disable = 0;
raw_spin_unlock_irqrestore(&parent_ctx->lock, flags);
child_ctx = child->perf_event_ctxp[ctxn];
if (child_ctx && inherited_all) {