Consider the following scenario, threads A and B:
(A)
* fdset_event_dispatch() start
* pfdentry->busy = 1;
* vhost_user_read_cb() start
* vhost_destroy_device() start
(B)
* rte_vhost_driver_unregister() start
* pthread_mutex_lock(&vsocket->conn_mutex);
* fdset_del()
* endless loop, waiting for pfdentry->busy == 0
(A)
* vhost_destroy_device() end
* pthread_mutex_lock(&vsocket->conn_mutex);
(mutex already locked - deadlock at this point)
Thread B has locked vsocket->conn_mutex and is in while(1)
loop waiting for given fd to change it's busy flag to 0.
Thread A would have to finish vhost_user_read_cb() in order
to set busy flag back to 0, but that can't happen due to
the vsocket->conn_mutex lock.
This patch synchronizes rte_vhost_driver_unregister() with
vhost_user_read_cb() through vhost_user.mutex.
Signed-off-by: Dariusz Stojaczyk <dariuszx.stojac...@intel.com>
---
lib/librte_vhost/socket.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/lib/librte_vhost/socket.c b/lib/librte_vhost/socket.c
index c7f99b0..77e58fe 100644
--- a/lib/librte_vhost/socket.c
+++ b/lib/librte_vhost/socket.c
@@ -273,6 +273,8 @@ vhost_user_read_cb(int connfd, void *dat, int *remove)
ret = vhost_user_msg_handler(conn->vid, connfd);
if (ret < 0) {
+ pthread_mutex_lock(&vhost_user.mutex);
+
close(connfd);
*remove = 1;
vhost_destroy_device(conn->vid);
@@ -287,6 +289,8 @@ vhost_user_read_cb(int connfd, void *dat, int *remove)
create_unix_socket(vsocket);
vhost_user_start_client(vsocket);
}
+
+ pthread_mutex_unlock(&vhost_user.mutex);
}
}
--
2.7.4
