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vhost: fix connect hang in client mode

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If something abnormal happened to QEMU, 'connect()' can block calling
thread (e.g. main thread of OVS) forever or for a really long time.
This can break whole application or block the reconnection thread.

Example with OVS:

	ovs_rcu(urcu2)|WARN|blocked 512000 ms waiting for main to quiesce
	(gdb) bt
	#0  connect () from /lib64/libpthread.so.0
	#1  vhost_user_create_client (vsocket=0xa816e0)
	#2  rte_vhost_driver_register
	#3  netdev_dpdk_vhost_user_construct
	#4  netdev_open (name=0xa664b0 "vhost1")
	[...]
	#11 main

Fix that by setting non-blocking mode for client sockets for connection.

Fixes: 64ab701c3d1e ("vhost: add vhost-user client mode")

Signed-off-by: Ilya Maximets <i.maximets@samsung.com>
Acked-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
This commit is contained in:
Ilya Maximets 2016-07-21 16:19:35 +03:00 committed by Thomas Monjalon
parent 53ecfa24fb
commit 81b5d22f1d
1 changed files with 48 additions and 4 deletions
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52
lib/librte_vhost/vhost_user/vhost-net-user.c
View File

@ -43,6 +43,7 @@
#include <sys/un.h>
#include <sys/queue.h>
#include <errno.h>
#include <fcntl.h>
#include <pthread.h>
#include <rte_log.h>
@ -445,6 +446,14 @@ create_unix_socket(const char *path, struct sockaddr_un *un, bool is_server)
RTE_LOG(INFO, VHOST_CONFIG, "vhost-user %s: socket created, fd: %d\n",
is_server ? "server" : "client", fd);
if (!is_server && fcntl(fd, F_SETFL, O_NONBLOCK)) {
RTE_LOG(ERR, VHOST_CONFIG,
"vhost-user: can't set nonblocking mode for socket, fd: "
"%d (%s)\n", fd, strerror(errno));
close(fd);
return -1;
}
memset(un, 0, sizeof(*un));
un->sun_family = AF_UNIX;
strncpy(un->sun_path, path, sizeof(un->sun_path));
@ -512,9 +521,33 @@ struct vhost_user_reconnect_list {
static struct vhost_user_reconnect_list reconn_list;
static pthread_t reconn_tid;
static int
vhost_user_connect_nonblock(int fd, struct sockaddr *un, size_t sz)
{
int ret, flags;
ret = connect(fd, un, sz);
if (ret < 0 && errno != EISCONN)
return -1;
flags = fcntl(fd, F_GETFL, 0);
if (flags < 0) {
RTE_LOG(ERR, VHOST_CONFIG,
"can't get flags for connfd %d\n", fd);
return -2;
}
if ((flags & O_NONBLOCK) && fcntl(fd, F_SETFL, flags & ~O_NONBLOCK)) {
RTE_LOG(ERR, VHOST_CONFIG,
"can't disable nonblocking on fd %d\n", fd);
return -2;
}
return 0;
}
static void *
vhost_user_client_reconnect(void *arg __rte_unused)
{
int ret;
struct vhost_user_reconnect *reconn, *next;
while (1) {
@ -528,13 +561,23 @@ vhost_user_client_reconnect(void *arg __rte_unused)
reconn != NULL; reconn = next) {
next = TAILQ_NEXT(reconn, next);
if (connect(reconn->fd, (struct sockaddr *)&reconn->un,
sizeof(reconn->un)) < 0)
ret = vhost_user_connect_nonblock(reconn->fd,
(struct sockaddr *)&reconn->un,
sizeof(reconn->un));
if (ret == -2) {
close(reconn->fd);
RTE_LOG(ERR, VHOST_CONFIG,
"reconnection for fd %d failed\n",
reconn->fd);
goto remove_fd;
}
if (ret == -1)
continue;
RTE_LOG(INFO, VHOST_CONFIG,
"%s: connected\n", reconn->vsocket->path);
vhost_user_add_connection(reconn->fd, reconn->vsocket);
remove_fd:
TAILQ_REMOVE(&reconn_list.head, reconn, next);
free(reconn);
}
@ -575,7 +618,8 @@ vhost_user_create_client(struct vhost_user_socket *vsocket)
if (fd < 0)
return -1;
ret = connect(fd, (struct sockaddr *)&un, sizeof(un));
ret = vhost_user_connect_nonblock(fd, (struct sockaddr *)&un,
sizeof(un));
if (ret == 0) {
vhost_user_add_connection(fd, vsocket);
return 0;
@ -585,7 +629,7 @@ vhost_user_create_client(struct vhost_user_socket *vsocket)
"failed to connect to %s: %s\n",
path, strerror(errno));
if (!vsocket->reconnect) {
if (ret == -2 || !vsocket->reconnect) {
close(fd);
return -1;
}