cls_can: Syntax fix

[lisovros/linux_canprio.git] / kernel / perf_event.c

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index db5b56064687e453c0df1cc118b975ea047bdcae..65b09a836cc3bdaed508cb1e050a174170241a8a 100644 (file)
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -1620,8 +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);
 }
@@ -1773,7 +1777,13 @@ static u64 perf_event_read(struct perf_event *event)
                unsigned long flags;
 
                raw_spin_lock_irqsave(&ctx->lock, flags);
-               update_context_time(ctx);
+               /*
+                * may read while context is not active
+                * (e.g., thread is blocked), in that case
+                * we cannot update context time
+                */
+               if (ctx->is_active)
+                       update_context_time(ctx);
                update_event_times(event);
                raw_spin_unlock_irqrestore(&ctx->lock, flags);
        }
@@ -2202,15 +2212,13 @@ static void perf_event_for_each(struct perf_event *event,
 static int perf_event_period(struct perf_event *event, u64 __user *arg)
 {
        struct perf_event_context *ctx = event->ctx;
-       unsigned long size;
        int ret = 0;
        u64 value;
 
        if (!event->attr.sample_period)
                return -EINVAL;
 
-       size = copy_from_user(&value, arg, sizeof(value));
-       if (size != sizeof(value))
+       if (copy_from_user(&value, arg, sizeof(value)))
                return -EFAULT;
 
        if (!value)
@@ -5618,6 +5626,7 @@ 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;
@@ -5658,6 +5667,15 @@ 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);
@@ -5665,6 +5683,10 @@ 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) {