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authorIngo Molnar <mingo@elte.hu>2008-11-13 08:58:31 -0500
committerIngo Molnar <mingo@elte.hu>2008-11-13 08:58:31 -0500
commitee51a1de7e3837577412be269e0100038068e691 (patch)
treea93d6dfeec829b61d6a74b5a9c841bcfeaeeb31d /kernel
parent47e74f2ba8fbf9fb1378e2524e6cfdc2fb37f160 (diff)
tracing: fix mmiotrace resizing crash
Pekka reported a crash when resizing the mmiotrace tracer (if only mmiotrace is enabled). This happens because in that case we do not allocate the max buffer, but we try to use it. Make ring_buffer_resize() idempotent against NULL buffers. Reported-by: Pekka Paalanen <pq@iki.fi> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/trace/ring_buffer.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 231db209fa8..036456cbb4f 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -538,6 +538,12 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size)
538 LIST_HEAD(pages); 538 LIST_HEAD(pages);
539 int i, cpu; 539 int i, cpu;
540 540
541 /*
542 * Always succeed at resizing a non-existent buffer:
543 */
544 if (!buffer)
545 return size;
546
541 size = DIV_ROUND_UP(size, BUF_PAGE_SIZE); 547 size = DIV_ROUND_UP(size, BUF_PAGE_SIZE);
542 size *= BUF_PAGE_SIZE; 548 size *= BUF_PAGE_SIZE;
543 buffer_size = buffer->pages * BUF_PAGE_SIZE; 549 buffer_size = buffer->pages * BUF_PAGE_SIZE;