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authorSteven Rostedt <srostedt@redhat.com>2010-01-06 20:40:44 -0500
committerSteven Rostedt <rostedt@goodmis.org>2010-01-06 20:40:44 -0500
commit0e1ff5d72a6393f2ef5dbf74f58bb55a12d63834 (patch)
treee9a9600a14fa4d1f2b045097c9e9d7d03463f0bf /kernel
parent5ded3dc6a3c7549b36a8ac27bbd81b33756a2c29 (diff)
ring-buffer: Add rb_list_head() wrapper around new reader page next field
If the very unlikely case happens where the writer moves the head by one between where the head page is read and where the new reader page is assigned _and_ the writer then writes and wraps the entire ring buffer so that the head page is back to what was originally read as the head page, the page to be swapped will have a corrupted next pointer. Simple solution is to wrap the assignment of the next pointer with a rb_list_head(). Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/trace/ring_buffer.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index d5b7308b7e1b..edefe3b2801b 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -2869,7 +2869,7 @@ rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer)
2869 * Splice the empty reader page into the list around the head. 2869 * Splice the empty reader page into the list around the head.
2870 */ 2870 */
2871 reader = rb_set_head_page(cpu_buffer); 2871 reader = rb_set_head_page(cpu_buffer);
2872 cpu_buffer->reader_page->list.next = reader->list.next; 2872 cpu_buffer->reader_page->list.next = rb_list_head(reader->list.next);
2873 cpu_buffer->reader_page->list.prev = reader->list.prev; 2873 cpu_buffer->reader_page->list.prev = reader->list.prev;
2874 2874
2875 /* 2875 /*