diff mbox series

[net,1/2] vhost_net: fix ubuf refcount incorrectly when sendmsg fails

Message ID 5e2ecf3d0f07b864d307b9f0425b7b7fe8bf4d2c.1608024547.git.wangyunjian@huawei.com (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series fixes for vhost_net | expand

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Commit Message

wangyunjian Dec. 15, 2020, 1:48 a.m. UTC 
From: Yunjian Wang <wangyunjian@huawei.com>

Currently the vhost_zerocopy_callback() maybe be called to decrease
the refcount when sendmsg fails in tun. The error handling in vhost
handle_tx_zerocopy() will try to decrease the same refcount again.
This is wrong. To fix this issue, we only call vhost_net_ubuf_put()
when vq->heads[nvq->desc].len == VHOST_DMA_IN_PROGRESS.

Fixes: 4477138fa0ae ("tun: properly test for IFF_UP")
Fixes: 90e33d459407 ("tun: enable napi_gro_frags() for TUN/TAP driver")

Signed-off-by: Yunjian Wang <wangyunjian@huawei.com>
---
 drivers/vhost/net.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

Comments

Willem de Bruijn Dec. 15, 2020, 2:45 a.m. UTC | #1 
On Mon, Dec 14, 2020 at 8:59 PM wangyunjian <wangyunjian@huawei.com> wrote:
>
> From: Yunjian Wang <wangyunjian@huawei.com>
>
> Currently the vhost_zerocopy_callback() maybe be called to decrease
> the refcount when sendmsg fails in tun. The error handling in vhost
> handle_tx_zerocopy() will try to decrease the same refcount again.
> This is wrong. To fix this issue, we only call vhost_net_ubuf_put()
> when vq->heads[nvq->desc].len == VHOST_DMA_IN_PROGRESS.
>
> Fixes: 4477138fa0ae ("tun: properly test for IFF_UP")
> Fixes: 90e33d459407 ("tun: enable napi_gro_frags() for TUN/TAP driver")
>
> Signed-off-by: Yunjian Wang <wangyunjian@huawei.com>

Patch looks good to me. Thanks.

But I think the right Fixes tag would be

Fixes: 0690899b4d45 ("tun: experimental zero copy tx support")
wangyunjian Dec. 15, 2020, 7:51 a.m. UTC | #2 
> -----Original Message-----
> From: Willem de Bruijn [mailto:willemdebruijn.kernel@gmail.com]
> Sent: Tuesday, December 15, 2020 10:46 AM
> To: wangyunjian <wangyunjian@huawei.com>
> Cc: Network Development <netdev@vger.kernel.org>; Michael S. Tsirkin
> <mst@redhat.com>; Jason Wang <jasowang@redhat.com>; Willem de Bruijn
> <willemdebruijn.kernel@gmail.com>; virtualization@lists.linux-foundation.org;
> Lilijun (Jerry) <jerry.lilijun@huawei.com>; chenchanghu
> <chenchanghu@huawei.com>; xudingke <xudingke@huawei.com>; huangbin (J)
> <brian.huangbin@huawei.com>
> Subject: Re: [PATCH net 1/2] vhost_net: fix ubuf refcount incorrectly when
> sendmsg fails
> 
> On Mon, Dec 14, 2020 at 8:59 PM wangyunjian <wangyunjian@huawei.com>
> wrote:
> >
> > From: Yunjian Wang <wangyunjian@huawei.com>
> >
> > Currently the vhost_zerocopy_callback() maybe be called to decrease
> > the refcount when sendmsg fails in tun. The error handling in vhost
> > handle_tx_zerocopy() will try to decrease the same refcount again.
> > This is wrong. To fix this issue, we only call vhost_net_ubuf_put()
> > when vq->heads[nvq->desc].len == VHOST_DMA_IN_PROGRESS.
> >
> > Fixes: 4477138fa0ae ("tun: properly test for IFF_UP")
> > Fixes: 90e33d459407 ("tun: enable napi_gro_frags() for TUN/TAP
> > driver")
> >
> > Signed-off-by: Yunjian Wang <wangyunjian@huawei.com>
> 
> Patch looks good to me. Thanks.
> 
> But I think the right Fixes tag would be
> 
> Fixes: 0690899b4d45 ("tun: experimental zero copy tx support")

OK, thanks for the suggestion. I will fix it in next version.
diff mbox series

Patch

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 531a00d703cd..c8784dfafdd7 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -863,6 +863,7 @@  static void handle_tx_zerocopy(struct vhost_net *net, struct socket *sock)
 	size_t len, total_len = 0;
 	int err;
 	struct vhost_net_ubuf_ref *ubufs;
+	struct ubuf_info *ubuf;
 	bool zcopy_used;
 	int sent_pkts = 0;
 
@@ -895,9 +896,7 @@  static void handle_tx_zerocopy(struct vhost_net *net, struct socket *sock)
 
 		/* use msg_control to pass vhost zerocopy ubuf info to skb */
 		if (zcopy_used) {
-			struct ubuf_info *ubuf;
 			ubuf = nvq->ubuf_info + nvq->upend_idx;
-
 			vq->heads[nvq->upend_idx].id = cpu_to_vhost32(vq, head);
 			vq->heads[nvq->upend_idx].len = VHOST_DMA_IN_PROGRESS;
 			ubuf->callback = vhost_zerocopy_callback;
@@ -927,7 +926,8 @@  static void handle_tx_zerocopy(struct vhost_net *net, struct socket *sock)
 		err = sock->ops->sendmsg(sock, &msg, len);
 		if (unlikely(err < 0)) {
 			if (zcopy_used) {
-				vhost_net_ubuf_put(ubufs);
+				if (vq->heads[ubuf->desc].len == VHOST_DMA_IN_PROGRESS)
+					vhost_net_ubuf_put(ubufs);
 				nvq->upend_idx = ((unsigned)nvq->upend_idx - 1)
 					% UIO_MAXIOV;
 			}