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vhost: fix race condition when adding fd in the fdset

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fdset_add can call fdset_shrink_nolock which call fdset_move
concurrently to poll that is call in fdset_event_dispatch.

This patch add a mutex to protect poll from been call at the same time
fdset_add call fdset_shrink_nolock.

Fixes: 1b815b8959 ("vhost: try to shrink pfdset when fdset_add fails")
Cc: stable@dpdk.org

Signed-off-by: Matthias Gatto <matthias.gatto@outscale.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
This commit is contained in:
Matthias Gatto 2018-12-06 16:00:07 +00:00 committed by Ferruh Yigit
parent 6ef75e405d
commit 276d63505b
3 changed files with 6 additions and 0 deletions
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4
lib/librte_vhost/fd_man.c
View File

@ -129,7 +129,9 @@ fdset_add(struct fdset *pfdset, int fd, fd_cb rcb, fd_cb wcb, void *dat)
pthread_mutex_lock(&pfdset->fd_mutex);
i = pfdset->num < MAX_FDS ? pfdset->num++ : -1;
if (i == -1) {
pthread_mutex_lock(&pfdset->fd_pooling_mutex);
fdset_shrink_nolock(pfdset);
pthread_mutex_unlock(&pfdset->fd_pooling_mutex);
i = pfdset->num < MAX_FDS ? pfdset->num++ : -1;
if (i == -1) {
pthread_mutex_unlock(&pfdset->fd_mutex);
@ -246,7 +248,9 @@ fdset_event_dispatch(void *arg)
numfds = pfdset->num;
pthread_mutex_unlock(&pfdset->fd_mutex);
pthread_mutex_lock(&pfdset->fd_pooling_mutex);
val = poll(pfdset->rwfds, numfds, 1000 /* millisecs */);
pthread_mutex_unlock(&pfdset->fd_pooling_mutex);
if (val < 0)
continue;

1
lib/librte_vhost/fd_man.h
View File

@ -24,6 +24,7 @@ struct fdset {
struct pollfd rwfds[MAX_FDS];
struct fdentry fd[MAX_FDS];
pthread_mutex_t fd_mutex;
pthread_mutex_t fd_pooling_mutex;
int num; /* current fd number of this fdset */
union pipefds {

1
lib/librte_vhost/socket.c
View File

@ -90,6 +90,7 @@ static struct vhost_user vhost_user = {
.fdset = {
.fd = { [0 ... MAX_FDS - 1] = {-1, NULL, NULL, NULL, 0} },
.fd_mutex = PTHREAD_MUTEX_INITIALIZER,
.fd_pooling_mutex = PTHREAD_MUTEX_INITIALIZER,
.num = 0
},
.vsocket_cnt = 0,