Messages in this thread Patch in this message | | | Date | Mon, 29 Sep 2008 20:23:48 +0200 | From | Frederic Weisbecker <> | Subject | [PATCH -tip 2/4] Tracing/ftrace: Fix pipe breaking |
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From: Pekka Paalanen <pq@iki.fi>
This patch fixes a bug which break the pipe when the seq is empty.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> --- kernel/trace/trace.c | 10 ++++++++-- 1 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 61f33da..ed10a68 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -2610,7 +2610,6 @@ 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); @@ -2621,6 +2620,8 @@ tracing_read_pipe(struct file *filp, char __user *ubuf, goto out; } +waitagain: + sret = 0; while (trace_empty(iter)) { if ((filp->f_flags & O_NONBLOCK)) { @@ -2754,8 +2755,13 @@ 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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