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authorPekka Paalanen <pq@iki.fi>2008-09-29 20:23:48 +0200
committerIngo Molnar <mingo@elte.hu>2008-10-14 10:39:01 +0200
commit9ff4b9744c187cae58c3774361ea090addbc4130 (patch)
treef001a85312b374fbd91d332eb341d02522512da1 /kernel/trace
parent2c4f035f6c3e8fda661eb6105aa51ef07aa71607 (diff)
downloadop-kernel-dev-9ff4b9744c187cae58c3774361ea090addbc4130.zip
op-kernel-dev-9ff4b9744c187cae58c3774361ea090addbc4130.tar.gz
tracing/ftrace: fix pipe breaking
This patch fixes a bug which break the pipe when the seq is empty. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/trace')
-rw-r--r--kernel/trace/trace.c10
1 files changed, 8 insertions, 2 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index b38a4bb..6a1c76b 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2439,7 +2439,6 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
if (sret != -EBUSY)
return sret;
- sret = 0;
trace_seq_reset(&iter->seq);
@@ -2450,6 +2449,8 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
goto out;
}
+waitagain:
+ sret = 0;
while (trace_empty(iter)) {
if ((filp->f_flags & O_NONBLOCK)) {
@@ -2556,8 +2557,13 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
if (iter->seq.readpos >= iter->seq.len)
trace_seq_reset(&iter->seq);
+
+ /*
+ * If there was nothing to send to user, inspite of consuming trace
+ * entries, go back to wait for more entries.
+ */
if (sret == -EBUSY)
- sret = 0;
+ goto waitagain;
out:
mutex_unlock(&trace_types_lock);
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