From: David Goulet <dgoulet@efficios.com>
Date: Tue, 16 Oct 2012 18:21:29 +0000 (-0400)
Subject: Fix: Empty metadata buffer(s) on HUP|ERR
X-Git-Tag: v2.1.0-rc5~24
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=4bb94b7597f56f5200ebd6a88e906488172241fb;p=lttng-tools.git

Fix: Empty metadata buffer(s) on HUP|ERR

The metadata fd was not emptying all the buffers on POLLHUP | POLLERR.
This patch makes the read subbuffer operation, for hung up metadata fd,
loop until the returned len is a negative value. For user space tracing,
-EAGAIN is returned and -ENODATA for the kernel tracer.

We also fixes another issue where an error returned (not -EAGAIN) by the
read subbuffer function call was stopping the thread. Now, the fd is
removed from the poll set, the stream is freed and the thread continues.

Fixes #378

Signed-off-by: David Goulet <dgoulet@efficios.com>
---

diff --git a/src/common/consumer.c b/src/common/consumer.c
index 242b05b3d..8b43257bd 100644
--- a/src/common/consumer.c
+++ b/src/common/consumer.c
@@ -1888,12 +1888,15 @@ restart:
 					lttng_ustconsumer_on_stream_hangup(stream);
 
 					/* We just flushed the stream now read it. */
-					len = ctx->on_buffer_ready(stream, ctx);
-					/* It's ok to have an unavailable sub-buffer */
-					if (len < 0 && len != -EAGAIN) {
-						rcu_read_unlock();
-						goto end;
-					}
+					do {
+						len = ctx->on_buffer_ready(stream, ctx);
+						/*
+						 * We don't check the return value here since if we get
+						 * a negative len, it means an error occured thus we
+						 * simply remove it from the poll set and free the
+						 * stream.
+						 */
+					} while (len > 0);
 				}
 
 				lttng_poll_del(&events, stream->wait_fd);