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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>
This commit is contained in:
Steven Rostedt 2009-05-06 10:26:45 -04:00 committed by Steven Rostedt
parent 35cf723e99
commit 8e7abf1c62
1 changed files with 3 additions and 5 deletions
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8
kernel/trace/ring_buffer.c
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@ -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);