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From: Patrick Fu <patrick.fu@intel.com>
To: dev@dpdk.org, maxime.coquelin@redhat.com, chenbo.xia@intel.com
Cc: zhihong.wang@intel.com, cheng1.jiang@intel.com, patrick.fu@intel.com
Subject: [dpdk-dev] [PATCH v1 4/4] vhost: fix async register/unregister deadlock
Date: Fri, 11 Sep 2020 09:53:16 +0800
Message-ID: <20200911015316.1903181-5-patrick.fu@intel.com> (raw)
In-Reply-To: <20200911015316.1903181-1-patrick.fu@intel.com>

When async register/unregister function is invoked in certain vhost
event callbacks (e.g. vring state change), deadlock may occur due to
recursive spinlock acquire. This patch removes unnecessary spinlock
from register API and use trylock() primitive in the unregister API
to avoid deadlock.

Fixes: 78639d54563a ("vhost: introduce async enqueue registration API")

Signed-off-by: Patrick Fu <patrick.fu@intel.com>
---
 lib/librte_vhost/vhost.c      | 13 +++++++------
 lib/librte_vhost/vhost_user.c |  4 ++--
 2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/lib/librte_vhost/vhost.c b/lib/librte_vhost/vhost.c
index ba374da67..8c2fee6b6 100644
--- a/lib/librte_vhost/vhost.c
+++ b/lib/librte_vhost/vhost.c
@@ -1576,8 +1576,6 @@ int rte_vhost_async_channel_register(int vid, uint16_t queue_id,
 		ops->transfer_data == NULL))
 		return -1;
 
-	rte_spinlock_lock(&vq->access_lock);
-
 	if (unlikely(vq->async_registered)) {
 		VHOST_LOG_CONFIG(ERR,
 			"async register failed: channel already registered "
@@ -1615,8 +1613,6 @@ int rte_vhost_async_channel_register(int vid, uint16_t queue_id,
 	vq->async_registered = true;
 
 reg_out:
-	rte_spinlock_unlock(&vq->access_lock);
-
 	return 0;
 }
 
@@ -1635,10 +1631,15 @@ int rte_vhost_async_channel_unregister(int vid, uint16_t queue_id)
 		return ret;
 
 	ret = 0;
-	rte_spinlock_lock(&vq->access_lock);
 
 	if (!vq->async_registered)
-		goto out;
+		return ret;
+
+	if (!rte_spinlock_trylock(&vq->access_lock)) {
+		VHOST_LOG_CONFIG(ERR, "Failed to unregister async channel. "
+			"virt queue busy.\n");
+		return -1;
+	}
 
 	if (vq->async_pkts_inflight_n) {
 		VHOST_LOG_CONFIG(ERR, "Failed to unregister async channel. "
diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
index f6cdbede7..39cd57aeb 100644
--- a/lib/librte_vhost/vhost_user.c
+++ b/lib/librte_vhost/vhost_user.c
@@ -2043,9 +2043,9 @@ vhost_user_set_vring_enable(struct virtio_net **pdev,
 		"set queue enable: %d to qp idx: %d\n",
 		enable, index);
 
-	if (!enable && dev->virtqueue[index]->async_registered) {
+	if (enable && dev->virtqueue[index]->async_registered) {
 		if (dev->virtqueue[index]->async_pkts_inflight_n) {
-			VHOST_LOG_CONFIG(ERR, "failed to disable vring. "
+			VHOST_LOG_CONFIG(ERR, "failed to enable vring. "
 			"async inflight packets must be completed first\n");
 			return RTE_VHOST_MSG_RESULT_ERR;
 		}
-- 
2.18.4


  parent reply	other threads:[~2020-09-11  2:01 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-11  1:53 [dpdk-dev] [PATCH v1 0/4] optimize async data path Patrick Fu
2020-09-11  1:53 ` [dpdk-dev] [PATCH v1 1/4] vhost: simplify async copy completion Patrick Fu
2020-09-23  9:07   ` Maxime Coquelin
2020-09-11  1:53 ` [dpdk-dev] [PATCH v1 2/4] vhost: dynamically alloc async memory Patrick Fu
2020-09-23  9:15   ` Maxime Coquelin
2020-09-29  5:55     ` Fu, Patrick
2020-09-11  1:53 ` [dpdk-dev] [PATCH v1 3/4] vhost: fix async vec buf overrun Patrick Fu
2020-09-23  9:21   ` Maxime Coquelin
2020-09-29  2:23     ` Fu, Patrick
2020-09-11  1:53 ` Patrick Fu [this message]
2020-09-29  6:29 ` [dpdk-dev] [PATCH v2 0/4] optimize async data path Patrick Fu
2020-09-29  6:29   ` [dpdk-dev] [PATCH v2 1/4] vhost: simplify async copy completion Patrick Fu
2020-09-29  6:29   ` [dpdk-dev] [PATCH v2 2/4] vhost: dynamically allocate async memory Patrick Fu
2020-09-29  6:29   ` [dpdk-dev] [PATCH v2 3/4] vhost: fix async vector buffer overrun Patrick Fu
2020-09-29  6:29   ` [dpdk-dev] [PATCH v2 4/4] vhost: fix async register/unregister deadlock Patrick Fu
2020-09-29  9:29 ` [dpdk-dev] [PATCH v3 0/4] optimize async data path Patrick Fu
2020-09-29  9:29   ` [dpdk-dev] [PATCH v3 1/4] vhost: simplify async copy completion Patrick Fu
2020-10-05 13:46     ` Maxime Coquelin
2020-10-09 11:16       ` Fu, Patrick
2020-09-29  9:29   ` [dpdk-dev] [PATCH v3 2/4] vhost: dynamically allocate async memory Patrick Fu
2020-10-05 13:50     ` Maxime Coquelin
2020-09-29  9:29   ` [dpdk-dev] [PATCH v3 3/4] vhost: fix async vector buffer overrun Patrick Fu
2020-10-05 14:19     ` Maxime Coquelin
2020-09-29  9:29   ` [dpdk-dev] [PATCH v3 4/4] vhost: fix async register/unregister deadlock Patrick Fu
2020-10-05 14:25     ` Maxime Coquelin
2020-10-09 10:54       ` Fu, Patrick
2020-10-13  1:45 ` [dpdk-dev] [PATCH v4 0/4] optimize async data path Patrick Fu
2020-10-13  1:45   ` [dpdk-dev] [PATCH v4 1/4] vhost: simplify async copy completion Patrick Fu
2020-10-14  9:28     ` Maxime Coquelin
2020-10-13  1:45   ` [dpdk-dev] [PATCH v4 2/4] vhost: dynamically allocate async memory Patrick Fu
2020-10-14  9:30     ` Maxime Coquelin
2020-10-13  1:45   ` [dpdk-dev] [PATCH v4 3/4] vhost: fix async vector buffer overrun Patrick Fu
2020-10-14  9:33     ` Maxime Coquelin
2020-10-13  1:45   ` [dpdk-dev] [PATCH v4 4/4] vhost: fix async unregister deadlock Patrick Fu
2020-10-14  9:34     ` Maxime Coquelin
2020-10-15 15:40   ` [dpdk-dev] [PATCH v4 0/4] optimize async data path Maxime Coquelin

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