Hi David,
> -----Original Message-----
> From: David Marchand <david.march...@redhat.com>
> Sent: Thursday, March 23, 2023 1:05 AM
> To: dev@dpdk.org
> Cc: sta...@dpdk.org; Maxime Coquelin <maxime.coque...@redhat.com>; Xia,
> Chenbo <chenbo....@intel.com>; Yuanhan Liu <y...@fridaylinux.org>
> Subject: [PATCH] vhost: avoid sleeping under mutex
>
> Covscan reported:
>
> 2. dpdk-21.11/lib/vhost/socket.c:852: lock_acquire: Calling function
> "pthread_mutex_lock" acquires lock "vhost_user.mutex".
> 23. dpdk-21.11/lib/vhost/socket.c:955: sleep: Call to
> "vhost_user_reconnect_init" might sleep while holding lock
> "vhost_user.mutex".
> # 953| vsocket->reconnect =
> !(flags & RTE_VHOST_USER_NO_RECONNECT);
> # 954| if (vsocket->reconnect && reconn_tid == 0) {
> # 955|-> if (vhost_user_reconnect_init() != 0)
> # 956| goto out_mutex;
> # 957| }
>
> The reason for this warning is that vhost_user_reconnect_init() creates a
> ctrl thread and calls nanosleep waiting for this thread to be ready,
> while vhost_user.mutex is taken.
>
> Move the call to vhost_user_reconnect_init() out of this mutex.
>
> While at it, a pthread_t value should be considered opaque.
> Instead of relying reconn_tid == 0, use an internal flag in
> vhost_user_reconnect_init().
Should we make reconn_tid not a global variable anymore then?
Maybe a static pthread_t in vhost_user_reconnect_init?
Thanks,
Chenbo
>
> Coverity issue: 373686
> Bugzilla ID: 981
> Fixes: e623e0c6d8a5 ("vhost: add reconnect ability")
> Cc: sta...@dpdk.org
>
> Signed-off-by: David Marchand <david.march...@redhat.com>
> ---
> lib/vhost/socket.c | 17 ++++++++++++-----
> 1 file changed, 12 insertions(+), 5 deletions(-)
>
> diff --git a/lib/vhost/socket.c b/lib/vhost/socket.c
> index 669c322e12..21002848e6 100644
> --- a/lib/vhost/socket.c
> +++ b/lib/vhost/socket.c
> @@ -498,8 +498,12 @@ vhost_user_client_reconnect(void *arg __rte_unused)
> static int
> vhost_user_reconnect_init(void)
> {
> + static bool reconn_init_done;
> int ret;
>
> + if (reconn_init_done)
> + return 0;
> +
> ret = pthread_mutex_init(&reconn_list.mutex, NULL);
> if (ret < 0) {
> VHOST_LOG_CONFIG("thread", ERR, "%s: failed to initialize
> mutex\n", __func__);
> @@ -515,6 +519,8 @@ vhost_user_reconnect_init(void)
> VHOST_LOG_CONFIG("thread", ERR,
> "%s: failed to destroy reconnect mutex\n",
> __func__);
> + } else {
> + reconn_init_done = true;
> }
>
> return ret;
> @@ -866,6 +872,11 @@ rte_vhost_driver_register(const char *path, uint64_t
> flags)
> if (!path)
> return -1;
>
> + if ((flags & RTE_VHOST_USER_CLIENT) != 0 &&
> + (flags & RTE_VHOST_USER_NO_RECONNECT) == 0 &&
> + vhost_user_reconnect_init() != 0)
> + return -1;
> +
> pthread_mutex_lock(&vhost_user.mutex);
>
> if (vhost_user.vsocket_cnt == MAX_VHOST_SOCKET) {
> @@ -961,11 +972,7 @@ rte_vhost_driver_register(const char *path, uint64_t
> flags)
> }
>
> if ((flags & RTE_VHOST_USER_CLIENT) != 0) {
> - vsocket->reconnect = !(flags & RTE_VHOST_USER_NO_RECONNECT);
> - if (vsocket->reconnect && reconn_tid == 0) {
> - if (vhost_user_reconnect_init() != 0)
> - goto out_mutex;
> - }
> + vsocket->reconnect = (flags & RTE_VHOST_USER_NO_RECONNECT) ==
> 0;
> } else {
> vsocket->is_server = true;
> }
> --
> 2.39.2
