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authorLinus Torvalds <torvalds@linux-foundation.org>2010-11-28 12:25:02 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2010-11-28 12:25:02 -0800
commita9e40a2493d805224f900d839b06188639b7ccd6 (patch)
treeb33c9477a0728f6299a00a3e817aa26872019576 /kernel
parent75f5d2c9bd36047364d1fb35c0720ab37df3be02 (diff)
parentee6dcfa40a50fe12a3ae0fb4d2653c66c3ed6556 (diff)
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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
* '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
Diffstat (limited to 'kernel')
-rw-r--r--kernel/perf_event.c24
1 files changed, 20 insertions, 4 deletions
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 671f6c8c8a3..eac7e336433 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -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) {