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authorSteven Rostedt <srostedt@redhat.com>2009-05-06 10:26:45 -0400
committerSteven Rostedt <rostedt@goodmis.org>2009-05-06 12:49:19 -0400
commit8e7abf1c62941ebb7a1416cbc62392c8a0902625 (patch)
tree72b62a8ce2cecee2ed0cff586fb8bed10cf0eb2d /kernel/trace/ring_buffer.c
parent35cf723e99c0e26ddf51f037dffaa4ff2c2c9106 (diff)
downloadop-kernel-dev-8e7abf1c62941ebb7a1416cbc62392c8a0902625.zip
op-kernel-dev-8e7abf1c62941ebb7a1416cbc62392c8a0902625.tar.gz
ring-buffer: remove unneeded conditional in rb_reserve_next
The code in __rb_reserve_next checks on page overflow if it is the original commiter and then resets the page back to the original setting. Although this is fine, and the code is correct, it is a bit fragil. Some experimental work I did breaks it easily. The better and more robust solution is to have all commiters that overflow the page, simply subtract what they added. [ Impact: more robust ring buffer account management ] Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace/ring_buffer.c')
-rw-r--r--kernel/trace/ring_buffer.c8
1 files changed, 3 insertions, 5 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 424129e..03ed52b 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -1290,9 +1290,8 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
rb_event_set_padding(event);
}
- if (tail <= BUF_PAGE_SIZE)
- /* Set the write back to the previous setting */
- local_set(&tail_page->write, tail);
+ /* Set the write back to the previous setting */
+ local_sub(length, &tail_page->write);
/*
* If this was a commit entry that failed,
@@ -1311,8 +1310,7 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
out_reset:
/* reset write */
- if (tail <= BUF_PAGE_SIZE)
- local_set(&tail_page->write, tail);
+ local_sub(length, &tail_page->write);
if (likely(lock_taken))
__raw_spin_unlock(&cpu_buffer->lock);
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