From: Gerrit Renker <grenker@cscs.ch>
Date: Thu, 25 Mar 2010 16:43:22 +0000 (+0100)
Subject: para_recv: handle EAGAIN on non-blocking socket
X-Git-Tag: v0.4.2~19
X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=commitdiff_plain;h=e5b21a60d783f22886a8671b7be444f1e1205c14

para_recv: handle EAGAIN on non-blocking socket

Checking whether the non-blocking socket is readable is not sufficient
to guarantee that EAGAIN is not encountered on the non-blocking socket,
the following was observed in the middle of a UDP/FEC stream:

Mar 24 17:12:44:0533 audi (0) decode_group: writing group 2784 (4232/4374 decoded data bytes)
Mar 24 17:12:44:0710 audi (0) get_time_string: slot 0: 32:42 [94:49] (26%/127:31)
Mar 24 17:12:44:0710 audi (2) btr_remove_node: removing btr node udp from buffer tree
Mar 24 17:12:44:0710 audi (1) unregister_task: unregistering udp receiver node (Resource temporarily unavailable)

The patch fixes the problem by not interpreting the case "data not
yet ready" as an error, but as a temporary condition.
---

diff --git a/dccp_recv.c b/dccp_recv.c
index c22fa84d..883451c6 100644
--- a/dccp_recv.c
+++ b/dccp_recv.c
@@ -166,6 +166,9 @@ static void dccp_recv_post_select(struct sched *s, struct task *t)
 	if (iovcnt == 0)
 		goto err;
 	ret = para_readv(pdd->fd, iov, iovcnt);
+	/* EAGAIN is possible even if FD_ISSET */
+	if (ret < 0 && is_errno(-ret, EAGAIN))
+		return;
 	if (ret == 0)
 		ret = -E_RECV_EOF;
 	if (ret < 0)
diff --git a/udp_recv.c b/udp_recv.c
index 4f363ccb..316957d5 100644
--- a/udp_recv.c
+++ b/udp_recv.c
@@ -92,6 +92,9 @@ static void udp_recv_post_select(__a_unused struct sched *s, struct task *t)
 	if (iovcnt == 0)
 		goto err;
 	ret = para_readv(purd->fd, iov, iovcnt);
+	/* EAGAIN is possible even if FD_ISSET */
+	if (ret < 0 && is_errno(-ret, EAGAIN))
+		return;
 	if (ret == 0)
 		ret = -E_RECV_EOF;
 	if (ret < 0)