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authorLiu Bo <bo.li.liu@oracle.com>2013-01-14 10:54:11 +0800
committerSteven Rostedt <rostedt@goodmis.org>2013-01-14 13:13:32 -0500
commit250bfd3d8e7e19cb649dd94689f0af2ce3474060 (patch)
tree66d0a49e15d99b4dabcd80259cdd501952425663
parent2df8f8a6a897ebf4c5613b5be6103d33b2a21520 (diff)
downloadlinux-stericsson-250bfd3d8e7e19cb649dd94689f0af2ce3474060.tar.gz
tracing: Fix regression of trace_pipe
Commit 0fb9656d "tracing: Make tracing_enabled be equal to tracing_on" changes the behaviour of trace_pipe, ie. it makes trace_pipe return if we've read something and tracing is enabled, and this means that we have to 'cat trace_pipe' again and again while running tests. IMO the right way is if tracing is enabled, we always block and wait for ring buffer, or we may lose what we want since ring buffer's size is limited. Link: http://lkml.kernel.org/r/1358132051-5410-1-git-send-email-bo.li.liu@oracle.com Signed-off-by: Liu Bo <bo.li.liu@oracle.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
-rw-r--r--kernel/trace/trace.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index f3ec1cfb0de1..3c13e46d7d24 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3454,7 +3454,7 @@ static int tracing_wait_pipe(struct file *filp)
return -EINTR;
/*
- * We block until we read something and tracing is enabled.
+ * We block until we read something and tracing is disabled.
* We still block if tracing is disabled, but we have never
* read anything. This allows a user to cat this file, and
* then enable tracing. But after we have read something,
@@ -3462,7 +3462,7 @@ static int tracing_wait_pipe(struct file *filp)
*
* iter->pos will be 0 if we haven't read anything.
*/
- if (tracing_is_enabled() && iter->pos)
+ if (!tracing_is_enabled() && iter->pos)
break;
}