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vhost: fix dead lock on closing in server mode

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When qemu close the unix socket fd of the vhostuser as a
server, and then immediately delete the vhostuser port on
openvswitch. There will be a deadlock.

A thread (fdset event thread):       B thread:
1. fdset_event_dispatch              rte_vhost_driver_unregister
2. set the fd busy to 1.             lock vsocket->conn_mutex
3. vhost_user_read_cb                fdset_del waits busy changed to 0.
4. vhost peer closed, remove the
   conn from vsocket->conn_list:
   lock vsocket->conn_mutex

5. set the fd busy to 0

Fixes: 65388b43f5 ("vhost: fix fd leaks for vhost-user server mode")
Cc: stable@dpdk.org

Signed-off-by: Tonghao Zhang <xiangxia.m.yue@gmail.com>
Acked-by: Maxime Coquelin <maxime.coquelin@redhat.com>
This commit is contained in:
Tonghao Zhang 2018-04-27 08:19:43 -07:00 committed by Ferruh Yigit
parent a24e7032f7
commit 8b4b949144
3 changed files with 46 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
lib/librte_vhost/fd_man.c
View File

@ -174,6 +174,38 @@ fdset_del(struct fdset *pfdset, int fd)
return dat;
}
/**
* Unregister the fd from the fdset.
*
* If parameters are invalid, return directly -2.
* And check whether fd is busy, if yes, return -1.
* Otherwise, try to delete the fd from fdset and
* return true.
*/
int
fdset_try_del(struct fdset *pfdset, int fd)
{
int i;
if (pfdset == NULL || fd == -1)
return -2;
pthread_mutex_lock(&pfdset->fd_mutex);
i = fdset_find_fd(pfdset, fd);
if (i != -1 && pfdset->fd[i].busy) {
pthread_mutex_unlock(&pfdset->fd_mutex);
return -1;
}
if (i != -1) {
pfdset->fd[i].fd = -1;
pfdset->fd[i].rcb = pfdset->fd[i].wcb = NULL;
pfdset->fd[i].dat = NULL;
}
pthread_mutex_unlock(&pfdset->fd_mutex);
return 0;
}
/**
* This functions runs in infinite blocking loop until there is no fd in

1
lib/librte_vhost/fd_man.h
View File

@ -44,6 +44,7 @@ int fdset_add(struct fdset *pfdset, int fd,
fd_cb rcb, fd_cb wcb, void *dat);
void *fdset_del(struct fdset *pfdset, int fd);
int fdset_try_del(struct fdset *pfdset, int fd);
void *fdset_event_dispatch(void *arg);

14
lib/librte_vhost/socket.c
View File

@ -922,13 +922,25 @@ rte_vhost_driver_unregister(const char *path)
vhost_user_remove_reconnect(vsocket);
}
again:
pthread_mutex_lock(&vsocket->conn_mutex);
for (conn = TAILQ_FIRST(&vsocket->conn_list);
conn != NULL;
conn = next) {
next = TAILQ_NEXT(conn, next);
fdset_del(&vhost_user.fdset, conn->connfd);
/*
* If r/wcb is executing, release the
* conn_mutex lock, and try again since
* the r/wcb may use the conn_mutex lock.
*/
if (fdset_try_del(&vhost_user.fdset,
conn->connfd) == -1) {
pthread_mutex_unlock(
&vsocket->conn_mutex);
goto again;
}
RTE_LOG(INFO, VHOST_CONFIG,
"free connfd = %d for device '%s'\n",
conn->connfd, path);