diff options
authorLinus Torvalds <torvalds@linux-foundation.org>2014-10-03 13:31:57 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-10-03 13:31:57 -0700
commit039001972a959ab31008a3924ff9519063371bc2 (patch)
parent7d1419f30cc5106196e54a282d7e115e698c95f6 (diff)
parent24607f114fd14f2f37e3e0cb3d47bce96e81e848 (diff)
Merge tag 'trace-fixes-v3.17-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull trace ring buffer iterator fix from Steven Rostedt: "While testing some new changes for 3.18, I kept hitting a bug every so often in the ring buffer. At first I thought it had to do with some of the changes I was working on, but then testing something else I realized that the bug was in 3.17 itself. I ran several bisects as the bug was not very reproducible, and finally came up with the commit that I could reproduce easily within a few minutes, and without the change I could run the tests over an hour without issue. The change fit the bug and I figured out a fix. That bad commit was: Commit 651e22f2701b "ring-buffer: Always reset iterator to reader page" This commit fixed a bug, but in the process created another one. It used the wrong value as the cached value that is used to see if things changed while an iterator was in use. This made it look like a change always happened, and could cause the iterator to go into an infinite loop" * tag 'trace-fixes-v3.17-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: ring-buffer: Fix infinite spin in reading buffer
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index b38fb2b9e237..2d75c94ae87d 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -3359,7 +3359,7 @@ static void rb_iter_reset(struct ring_buffer_iter *iter)
iter->head = cpu_buffer->reader_page->read;
iter->cache_reader_page = iter->head_page;
- iter->cache_read = iter->head;
+ iter->cache_read = cpu_buffer->read;
if (iter->head)
iter->read_stamp = cpu_buffer->read_stamp;

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