From: David Marchand <david.marchand@redhat.com>
To: Wenwu Ma <wenwux.ma@intel.com>
Cc: Maxime Coquelin <maxime.coquelin@redhat.com>,
"Xia, Chenbo" <chenbo.xia@intel.com>, dev <dev@dpdk.org>,
Jiayu Hu <jiayu.hu@intel.com>,
"Wang, Yinan" <yinan.wang@intel.com>,
xingguang.he@intel.com
Subject: Re: [PATCH] vhost: fix deadlock when handling user messages
Date: Thu, 5 May 2022 09:21:59 +0200 [thread overview]
Message-ID: <CAJFAV8wE4UNt08QZ_OxNoy6fBYrvi1S=9O2r=svaOQL1gKJavw@mail.gmail.com> (raw)
In-Reply-To: <20220505134008.2865-1-wenwux.ma@intel.com>
Hello,
On Thu, May 5, 2022 at 7:42 AM Wenwu Ma <wenwux.ma@intel.com> wrote:
>
> In vhost_user_msg_handler(), if vhost message handling
> failed, we should check whether the queue is locked and
> release the lock before returning. Or, it will cause a
> deadlock later.
Fixes: 7f31d4ea05ca ("vhost: fix lock on device readiness notification")
Cc: stable@dpdk.org
>
> Signed-off-by: Wenwu Ma <wenwux.ma@intel.com>
> ---
> lib/vhost/vhost_user.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/lib/vhost/vhost_user.c b/lib/vhost/vhost_user.c
> index 1d390677fa..80a5df6e9d 100644
> --- a/lib/vhost/vhost_user.c
> +++ b/lib/vhost/vhost_user.c
> @@ -3113,6 +3113,8 @@ vhost_user_msg_handler(int vid, int fd)
> send_vhost_reply(dev, fd, &ctx);
> } else if (ret == RTE_VHOST_MSG_RESULT_ERR) {
> VHOST_LOG_CONFIG(ERR, "(%s) vhost message handling failed.\n", dev->ifname);
> + if (unlock_required)
> + vhost_user_unlock_all_queue_pairs(dev);
> return -1;
> }
>
This fixes the issue, but my concern is that changes in the future
might introduce a new return statement (forgetting to unlock).
I suggest having a single return statement, like:
diff --git a/lib/vhost/vhost_user.c b/lib/vhost/vhost_user.c
index 1d390677fa..4baf969ee0 100644
--- a/lib/vhost/vhost_user.c
+++ b/lib/vhost/vhost_user.c
@@ -2976,7 +2976,6 @@ vhost_user_msg_handler(int vid, int fd)
return -1;
}
- ret = 0;
request = ctx.msg.request.master;
if (request > VHOST_USER_NONE && request < VHOST_USER_MAX &&
vhost_message_str[request]) {
@@ -3113,9 +3112,11 @@ vhost_user_msg_handler(int vid, int fd)
send_vhost_reply(dev, fd, &ctx);
} else if (ret == RTE_VHOST_MSG_RESULT_ERR) {
VHOST_LOG_CONFIG(ERR, "(%s) vhost message handling
failed.\n", dev->ifname);
- return -1;
+ ret = -1;
+ goto unlock;
}
+ ret = 0;
for (i = 0; i < dev->nr_vring; i++) {
struct vhost_virtqueue *vq = dev->virtqueue[i];
bool cur_ready = vq_is_ready(dev, vq);
@@ -3126,10 +3127,11 @@ vhost_user_msg_handler(int vid, int fd)
}
}
+unlock:
if (unlock_required)
vhost_user_unlock_all_queue_pairs(dev);
- if (!virtio_is_ready(dev))
+ if (ret != 0 || !virtio_is_ready(dev))
goto out;
/*
@@ -3156,7 +3158,7 @@ vhost_user_msg_handler(int vid, int fd)
}
out:
- return 0;
+ return ret;
}
static int process_slave_message_reply(struct virtio_net *dev,
--
David Marchand
next prev parent reply other threads:[~2022-05-05 7:22 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-05 13:40 Wenwu Ma
2022-05-05 7:21 ` David Marchand [this message]
2022-05-05 16:17 ` [PATCH v2] " Wenwu Ma
2022-05-06 8:19 ` Xia, Chenbo
2022-05-07 13:27 ` [PATCH v3] vhost: fix deadlock when message handling failed Wenwu Ma
2022-05-07 6:02 ` Xia, Chenbo
2022-05-09 3:13 ` Ling, WeiX
2022-05-17 13:15 ` David Marchand
2022-05-17 13:24 ` Maxime Coquelin
2022-07-11 8:42 ` Pei, Andy
2022-07-11 8:54 ` Xia, Chenbo
2022-07-11 9:02 ` Pei, Andy
2022-07-11 9:14 ` Xia, Chenbo
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