diff options
Diffstat (limited to 'kernel/perf_event.c')
| -rw-r--r-- | kernel/perf_event.c | 22 |
1 files changed, 20 insertions, 2 deletions
diff --git a/kernel/perf_event.c b/kernel/perf_event.c index ac869dc7896..d1a6c04d839 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -1609,8 +1609,12 @@ 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); } @@ -5596,6 +5600,7 @@ int perf_event_init_task(struct task_struct *child) struct perf_event *event; struct task_struct *parent = current; int inherited_all = 1; + unsigned long flags; int ret = 0; child->perf_event_ctxp = NULL; @@ -5636,6 +5641,15 @@ int perf_event_init_task(struct task_struct *child) 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, &inherited_all); @@ -5643,6 +5657,10 @@ int perf_event_init_task(struct task_struct *child) 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; if (child_ctx && inherited_all) { |