diff options
| author | Steven Rostedt <srostedt@redhat.com> | 2013-02-28 13:44:11 -0500 |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2013-03-15 00:34:49 -0400 |
| commit | b627344fef0c38fa4e3050348e168e46db87c905 (patch) | |
| tree | d828a640959fcb39667cbc56cd7cf8e75f34636f /kernel/trace/trace.c | |
| parent | cc60cdc952be09bca5b0bff9fefc7aa6185c3049 (diff) | |
tracing: Fix read blocking on trace_pipe_raw
If the ring buffer is empty, a read to trace_pipe_raw wont block.
The tracing code has the infrastructure to wake up waiting readers,
but the trace_pipe_raw doesn't take advantage of that.
When a read is done to trace_pipe_raw without the O_NONBLOCK flag
set, have the read block until there's data in the requested buffer.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace/trace.c')
| -rw-r--r-- | kernel/trace/trace.c | 18 |
1 files changed, 15 insertions, 3 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 4a6e461273a..3ec146c96df 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4389,6 +4389,7 @@ static int tracing_buffers_open(struct inode *inode, struct file *filp) info->iter.tr = tr; info->iter.cpu_file = tc->cpu; + info->iter.trace = tr->current_trace; info->spare = NULL; /* Force reading ring buffer for first read */ info->read = (unsigned int)-1; @@ -4428,18 +4429,29 @@ tracing_buffers_read(struct file *filp, char __user *ubuf, if (info->read < PAGE_SIZE) goto read; + again: trace_access_lock(iter->cpu_file); ret = ring_buffer_read_page(iter->tr->buffer, &info->spare, count, iter->cpu_file, 0); trace_access_unlock(iter->cpu_file); - if (ret < 0) + + if (ret < 0) { + if (trace_empty(iter)) { + if ((filp->f_flags & O_NONBLOCK)) + return -EAGAIN; + iter->trace->wait_pipe(iter); + if (signal_pending(current)) + return -EINTR; + goto again; + } return 0; + } info->read = 0; -read: + read: size = PAGE_SIZE - info->read; if (size > count) size = count; @@ -4616,7 +4628,7 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos, ret = -EAGAIN; goto out; } - default_wait_pipe(iter); + iter->trace->wait_pipe(iter); if (signal_pending(current)) { ret = -EINTR; goto out; |