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vhost: fix deadlock on port deletion

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If the vhost-user application (e.g. OVS) deletes the vhost-user
port while Qemu sends a vhost-user request, a deadlock can
happen if the request handler tries to acquire vhost-user's
global mutex, which is also locked by the vhost-user port
deletion API (rte_vhost_driver_unregister).

This patch prevents the deadlock by making
rte_vhost_driver_unregister() to release the mutex and try
again if a request is being handled to give a chance to
the request handler to complete.

Fixes: 8b4b949144b8 ("vhost: fix dead lock on closing in server mode")
Fixes: 5fbb3941da9f ("vhost: introduce driver features related APIs")
Cc: stable@dpdk.org

Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Reviewed-by: Tiwei Bie <tiwei.bie@intel.com>
Acked-by: Eelco Chaudron <echaudro@redhat.com>
This commit is contained in:
Maxime Coquelin 2020-01-14 19:53:57 +01:00 committed by Ferruh Yigit
parent 1ad2f882b3
commit 5efb18e85f
1 changed files with 15 additions and 5 deletions
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20
lib/librte_vhost/socket.c
View File

@ -1052,9 +1052,10 @@ again:
next = TAILQ_NEXT(conn, next);
/*
* If r/wcb is executing, release the
* conn_mutex lock, and try again since
* the r/wcb may use the conn_mutex lock.
* If r/wcb is executing, release vsocket's
* conn_mutex and vhost_user's mutex locks, and
* try again since the r/wcb may use the
* conn_mutex and mutex locks.
*/
if (fdset_try_del(&vhost_user.fdset,
conn->connfd) == -1) {
@ -1075,8 +1076,17 @@ again:
pthread_mutex_unlock(&vsocket->conn_mutex);
if (vsocket->is_server) {
fdset_del(&vhost_user.fdset,
vsocket->socket_fd);
/*
* If r/wcb is executing, release vhost_user's
* mutex lock, and try again since the r/wcb
* may use the mutex lock.
*/
if (fdset_try_del(&vhost_user.fdset,
vsocket->socket_fd) == -1) {
pthread_mutex_unlock(&vhost_user.mutex);
goto again;
}
close(vsocket->socket_fd);
unlink(path);
} else if (vsocket->reconnect) {