path: root/kernel
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authorLinus Torvalds <torvalds@linux-foundation.org>2013-01-14 20:22:16 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2013-01-14 20:22:16 -0800
commit406089d01562f1e2bf9f089fd7637009ebaad589 (patch)
tree1b8202a1b91354eb8abb7b35eef2cee02ef92a75 /kernel
parent7dea1ff3b7b48356c02cb00d6a4e8d5aaf680830 (diff)
parent250bfd3d8e7e19cb649dd94689f0af2ce3474060 (diff)
Merge tag 'trace-3.8-rc3-regression-fix' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing regression fixes from Steven Rostedt: "The clean up patch commit 0fb9656d957d "tracing: Make tracing_enabled be equal to tracing_on" caused two regressions. 1) The irqs off latency tracer no longer starts if tracing_on is off when the tracer is set, and then tracing_on is enabled. The tracing_on file needs the hook that tracing_enabled had to enable tracers if they request it (call the tracer's start() method). 2) That commit had a separate change that really should have been a separate patch, but it must have been added accidently with the -a option of git commit. But as the change is still related to the commit it wasn't noticed in review. That change, changed the way blocking is done by the trace_pipe file with respect to the tracing_on settings. I've been told that this change breaks current userspace, and this specific change is being reverted." * tag 'trace-3.8-rc3-regression-fix' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: tracing: Fix regression of trace_pipe tracing: Fix regression with irqsoff tracer and tracing_on file
Diffstat (limited to 'kernel')
1 files changed, 11 insertions, 4 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 1bbfa044650..3c13e46d7d2 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)
@@ -4817,10 +4817,17 @@ rb_simple_write(struct file *filp, const char __user *ubuf,
return ret;
if (buffer) {
- if (val)
+ mutex_lock(&trace_types_lock);
+ if (val) {
- else
+ if (current_trace->start)
+ current_trace->start(tr);
+ } else {
+ if (current_trace->stop)
+ current_trace->stop(tr);
+ }
+ mutex_unlock(&trace_types_lock);