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

* 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  tracing: Fix return of trace_dump_stack()
  ksym_tracer: Fix bad cast
  tracing/power: Remove two exports
  tracing: Change event->profile_count to be int type
  tracing: Simplify trace_option_write()
  tracing: Remove useless trace option
  tracing: Use seq file for trace_clock
  tracing: Use seq file for trace_options
  function-graph: Allow writing the same val to set_graph_function
  ftrace: Call trace_parser_clear() properly
  ftrace: Return EINVAL when writing invalid val to set_ftrace_filter
  tracing: Move a printk out of ftrace_raw_reg_event_foo()
  tracing: Pull up calls to trace_define_common_fields()
  tracing: Extract duplicate ftrace_raw_init_event_foo()
  ftrace.h: Use common pr_info fmt string
  tracing: Add stack trace to irqsoff tracer
  tracing: Add trace_dump_stack()
  ring-buffer: Move resize integrity check under reader lock
  ring-buffer: Use sync sched protection on ring buffer resizing
  tracing: Fix wrong usage of strstrip in trace_ksyms

1 files changed, 11 insertions, 18 deletions

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index f58c9ad15830..2326b04c95c4 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -1193,9 +1193,6 @@ rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned nr_pages)
 	struct list_head *p;
 	unsigned i;
 
-	atomic_inc(&cpu_buffer->record_disabled);
-	synchronize_sched();
-
 	spin_lock_irq(&cpu_buffer->reader_lock);
 	rb_head_page_deactivate(cpu_buffer);
 
@@ -1211,12 +1208,9 @@ rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned nr_pages)
 		return;
 
 	rb_reset_cpu(cpu_buffer);
-	spin_unlock_irq(&cpu_buffer->reader_lock);
-
 	rb_check_pages(cpu_buffer);
 
-	atomic_dec(&cpu_buffer->record_disabled);
-
+	spin_unlock_irq(&cpu_buffer->reader_lock);
 }
 
 static void
@@ -1227,9 +1221,6 @@ rb_insert_pages(struct ring_buffer_per_cpu *cpu_buffer,
 	struct list_head *p;
 	unsigned i;
 
-	atomic_inc(&cpu_buffer->record_disabled);
-	synchronize_sched();
-
 	spin_lock_irq(&cpu_buffer->reader_lock);
 	rb_head_page_deactivate(cpu_buffer);
 
@@ -1242,11 +1233,9 @@ rb_insert_pages(struct ring_buffer_per_cpu *cpu_buffer,
 		list_add_tail(&bpage->list, cpu_buffer->pages);
 	}
 	rb_reset_cpu(cpu_buffer);
-	spin_unlock_irq(&cpu_buffer->reader_lock);
-
 	rb_check_pages(cpu_buffer);
 
-	atomic_dec(&cpu_buffer->record_disabled);
+	spin_unlock_irq(&cpu_buffer->reader_lock);
 }
 
 /**
@@ -1254,11 +1243,6 @@ rb_insert_pages(struct ring_buffer_per_cpu *cpu_buffer,
  * @buffer: the buffer to resize.
  * @size: the new size.
  *
- * The tracer is responsible for making sure that the buffer is
- * not being used while changing the size.
- * Note: We may be able to change the above requirement by using
- *  RCU synchronizations.
- *
  * Minimum size is 2 * BUF_PAGE_SIZE.
  *
  * Returns -1 on failure.
@@ -1290,6 +1274,11 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size)
 	if (size == buffer_size)
 		return size;
 
+	atomic_inc(&buffer->record_disabled);
+
+	/* Make sure all writers are done with this buffer. */
+	synchronize_sched();
+
 	mutex_lock(&buffer->mutex);
 	get_online_cpus();
 
@@ -1352,6 +1341,8 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size)
 	put_online_cpus();
 	mutex_unlock(&buffer->mutex);
 
+	atomic_dec(&buffer->record_disabled);
+
 	return size;
 
  free_pages:
@@ -1361,6 +1352,7 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size)
 	}
 	put_online_cpus();
 	mutex_unlock(&buffer->mutex);
+	atomic_dec(&buffer->record_disabled);
 	return -ENOMEM;
 
 	/*
@@ -1370,6 +1362,7 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size)
  out_fail:
 	put_online_cpus();
 	mutex_unlock(&buffer->mutex);
+	atomic_dec(&buffer->record_disabled);
 	return -1;
 }
 EXPORT_SYMBOL_GPL(ring_buffer_resize);