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| author | Steven Rostedt <srostedt@redhat.com> | 2009-04-21 09:41:26 -0400 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-04-21 16:00:45 +0200 |
| commit | 3554228d4289098a8fe5cfd87512ec32a19bbe5a (patch) | |
| tree | 6153783ba611e8d55eb4f6dde08526ee733cfb4a | |
| parent | f66578a7637b87810cbb9041c4e3a77fd2fa4706 (diff) | |
| download | op-kernel-dev-3554228d4289098a8fe5cfd87512ec32a19bbe5a.zip op-kernel-dev-3554228d4289098a8fe5cfd87512ec32a19bbe5a.tar.gz | |
ring-buffer: only warn on wrap if buffer is bigger than two pages
On boot up, to save memory, ftrace allocates the minimum buffer
which is two pages. Ftrace also goes through a series of tests
(when configured) on boot up. These tests can fill up a page within
a single interrupt.
The ring buffer also has a WARN_ON when it detects that the buffer was
completely filled within a single commit (other commits are allowed to
be nested).
Combine the small buffer on start up, with the tests that can fill more
than a single page within an interrupt, this can trigger the WARN_ON.
This patch makes the WARN_ON only happen when the ring buffer consists
of more than two pages.
[ Impact: prevent false WARN_ON in ftrace startup tests ]
Reported-by: Ingo Molnar <mingo@elte.hu>
LKML-Reference: <20090421094616.GA14561@elte.hu>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
| -rw-r--r-- | kernel/trace/ring_buffer.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 7bcfd3e..61dbdf2 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -1241,7 +1241,8 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, * about it. */ if (unlikely(next_page == commit_page)) { - WARN_ON_ONCE(1); + /* This can easily happen on small ring buffers */ + WARN_ON_ONCE(buffer->pages > 2); goto out_reset; } |
