[PATCH net-next 0/2] net: ubuf_info.refcnt conversion

[PATCH net-next 0/2] net: ubuf_info.refcnt conversion

[Eric Dumazet]

Yet another atomic_t -> refcount_t conversion, split in two patches.

First patch prepares the automatic conversion done in the second patch.

Eric Dumazet (2):
  net: prepare (struct ubuf_info)->refcnt conversion
  net: convert (struct ubuf_info)->refcnt to refcount_t

 include/linux/skbuff.h | 5 +++--
 net/core/skbuff.c      | 9 +++++----
 net/ipv4/tcp.c         | 2 --
 3 files changed, 8 insertions(+), 8 deletions(-)

-- 
2.14.1.581.gf28d330327-goog

[PATCH net-next 1/2] net: prepare (struct ubuf_info)->refcnt conversion

[Eric Dumazet]

In order to convert this atomic_t refcnt to refcount_t,
we need to init the refcount to one to not trigger
a 0 -> 1 transition.

This also removes one atomic operation in fast path.

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 net/core/skbuff.c | 3 ++-
 net/ipv4/tcp.c    | 2 --
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 917da73d3ab3b82163cf0a9ee944da09cb5a391f..65b9ca3945f8fd2b1bef4aef5dd774be04e5d128 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -963,7 +963,7 @@ struct ubuf_info *sock_zerocopy_alloc(struct sock *sk, size_t size)
 	uarg->len = 1;
 	uarg->bytelen = size;
 	uarg->zerocopy = 1;
-	atomic_set(&uarg->refcnt, 0);
+	atomic_set(&uarg->refcnt, 1);
 	sock_hold(sk);
 
 	return uarg;
@@ -1005,6 +1005,7 @@ struct ubuf_info *sock_zerocopy_realloc(struct sock *sk, size_t size,
 			uarg->len++;
 			uarg->bytelen = bytelen;
 			atomic_set(&sk->sk_zckey, ++next);
+			sock_zerocopy_get(uarg);
 			return uarg;
 		}
 	}
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 21ca2df274c5130a13d31a391a1408d779af34af..fff4d7bc3b8b46174e7bd0a04d7c212307e55cb5 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1190,8 +1190,6 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size)
 			goto out_err;
 		}
 
-		/* skb may be freed in main loop, keep extra ref on uarg */
-		sock_zerocopy_get(uarg);
 		if (!(sk_check_csum_caps(sk) && sk->sk_route_caps & NETIF_F_SG))
 			uarg->zerocopy = 0;
 	}
-- 
2.14.1.581.gf28d330327-goog

Re: [PATCH net-next 1/2] net: prepare (struct ubuf_info)->refcnt conversion

[Willem de Bruijn]

On Thu, Aug 31, 2017 at 4:30 PM, Eric Dumazet <edumazet@google.com> wrote:
> In order to convert this atomic_t refcnt to refcount_t,
> we need to init the refcount to one to not trigger
> a 0 -> 1 transition.
>
> This also removes one atomic operation in fast path.
>
> Signed-off-by: Eric Dumazet <edumazet@google.com>

Acked-by: Willem de Bruijn <willemb@google.com>

Thanks, Eric.

[PATCH net-next 2/2] net: convert (struct ubuf_info)->refcnt to refcount_t

[Eric Dumazet]

refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 include/linux/skbuff.h | 5 +++--
 net/core/skbuff.c      | 8 ++++----
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 7594e19bce622a38dc39c054093c3da15b99b67b..316a92b45351f53709886ee0099cbc83b66f1b15 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -22,6 +22,7 @@
 #include <linux/cache.h>
 #include <linux/rbtree.h>
 #include <linux/socket.h>
+#include <linux/refcount.h>
 
 #include <linux/atomic.h>
 #include <asm/types.h>
@@ -456,7 +457,7 @@ struct ubuf_info {
 			u32 bytelen;
 		};
 	};
-	atomic_t refcnt;
+	refcount_t refcnt;
 
 	struct mmpin {
 		struct user_struct *user;
@@ -472,7 +473,7 @@ struct ubuf_info *sock_zerocopy_realloc(struct sock *sk, size_t size,
 
 static inline void sock_zerocopy_get(struct ubuf_info *uarg)
 {
-	atomic_inc(&uarg->refcnt);
+	refcount_inc(&uarg->refcnt);
 }
 
 void sock_zerocopy_put(struct ubuf_info *uarg);
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 65b9ca3945f8fd2b1bef4aef5dd774be04e5d128..ed86ca9afd9d8d1ac47983acf6006c179285a612 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -963,7 +963,7 @@ struct ubuf_info *sock_zerocopy_alloc(struct sock *sk, size_t size)
 	uarg->len = 1;
 	uarg->bytelen = size;
 	uarg->zerocopy = 1;
-	atomic_set(&uarg->refcnt, 1);
+	refcount_set(&uarg->refcnt, 1);
 	sock_hold(sk);
 
 	return uarg;
@@ -1086,7 +1086,7 @@ EXPORT_SYMBOL_GPL(sock_zerocopy_callback);
 
 void sock_zerocopy_put(struct ubuf_info *uarg)
 {
-	if (uarg && atomic_dec_and_test(&uarg->refcnt)) {
+	if (uarg && refcount_dec_and_test(&uarg->refcnt)) {
 		if (uarg->callback)
 			uarg->callback(uarg, uarg->zerocopy);
 		else
@@ -1108,7 +1108,7 @@ void sock_zerocopy_put_abort(struct ubuf_info *uarg)
 		 * avoid an skb send inside the main loop triggering uarg free.
 		 */
 		if (sk->sk_type != SOCK_STREAM)
-			atomic_inc(&uarg->refcnt);
+			refcount_inc(&uarg->refcnt);
 
 		sock_zerocopy_put(uarg);
 	}
@@ -1490,7 +1490,7 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
 		if (skb_orphan_frags(skb, gfp_mask))
 			goto nofrags;
 		if (skb_zcopy(skb))
-			atomic_inc(&skb_uarg(skb)->refcnt);
+			refcount_inc(&skb_uarg(skb)->refcnt);
 		for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
 			skb_frag_ref(skb, i);
 
-- 
2.14.1.581.gf28d330327-goog

Re: [PATCH net-next 2/2] net: convert (struct ubuf_info)->refcnt to refcount_t

[Willem de Bruijn]

On Thu, Aug 31, 2017 at 4:30 PM, Eric Dumazet <edumazet@google.com> wrote:
> refcount_t type and corresponding API should be
> used instead of atomic_t when the variable is used as
> a reference counter. This allows to avoid accidental
> refcounter overflows that might lead to use-after-free
> situations.
>
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> ---
>  include/linux/skbuff.h | 5 +++--
>  net/core/skbuff.c      | 8 ++++----
>  2 files changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> index 7594e19bce622a38dc39c054093c3da15b99b67b..316a92b45351f53709886ee0099cbc83b66f1b15 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -22,6 +22,7 @@
>  #include <linux/cache.h>
>  #include <linux/rbtree.h>
>  #include <linux/socket.h>
> +#include <linux/refcount.h>
>
>  #include <linux/atomic.h>
>  #include <asm/types.h>
> @@ -456,7 +457,7 @@ struct ubuf_info {
>                         u32 bytelen;
>                 };
>         };
> -       atomic_t refcnt;
> +       refcount_t refcnt;
>
>         struct mmpin {
>                 struct user_struct *user;
> @@ -472,7 +473,7 @@ struct ubuf_info *sock_zerocopy_realloc(struct sock *sk, size_t size,
>
>  static inline void sock_zerocopy_get(struct ubuf_info *uarg)
>  {
> -       atomic_inc(&uarg->refcnt);
> +       refcount_inc(&uarg->refcnt);
>  }
>
>  void sock_zerocopy_put(struct ubuf_info *uarg);
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index 65b9ca3945f8fd2b1bef4aef5dd774be04e5d128..ed86ca9afd9d8d1ac47983acf6006c179285a612 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -963,7 +963,7 @@ struct ubuf_info *sock_zerocopy_alloc(struct sock *sk, size_t size)
>         uarg->len = 1;
>         uarg->bytelen = size;
>         uarg->zerocopy = 1;
> -       atomic_set(&uarg->refcnt, 1);
> +       refcount_set(&uarg->refcnt, 1);
>         sock_hold(sk);
>
>         return uarg;
> @@ -1086,7 +1086,7 @@ EXPORT_SYMBOL_GPL(sock_zerocopy_callback);
>
>  void sock_zerocopy_put(struct ubuf_info *uarg)
>  {
> -       if (uarg && atomic_dec_and_test(&uarg->refcnt)) {
> +       if (uarg && refcount_dec_and_test(&uarg->refcnt)) {
>                 if (uarg->callback)
>                         uarg->callback(uarg, uarg->zerocopy);
>                 else
> @@ -1108,7 +1108,7 @@ void sock_zerocopy_put_abort(struct ubuf_info *uarg)
>                  * avoid an skb send inside the main loop triggering uarg free.
>                  */
>                 if (sk->sk_type != SOCK_STREAM)
> -                       atomic_inc(&uarg->refcnt);
> +                       refcount_inc(&uarg->refcnt);

This would be a 0 -> 1 transition. It is taken only on the error path from
a socket that does not take an explicit hold at the start of sendmsg.

The code is vestigial, really, as the final patchset only includes tcp.
It is safe to leave as is for now, or I can remove it.

In 1f8b977ab32d ("sock: enable MSG_ZEROCOPY") I also updated
other users of ubuf_info to initialize refcnt. We probably also want to
convert the call in handle_tx in drivers/vhost/net.c.

Re: [PATCH net-next 2/2] net: convert (struct ubuf_info)->refcnt to refcount_t

[Eric Dumazet]

On Thu, 2017-08-31 at 18:45 -0400, Willem de Bruijn wrote:
> On Thu, Aug 31, 2017 at 4:30 PM, Eric Dumazet <edumazet@google.com> wrote:
> > refcount_t type and corresponding API should be
> > used instead of atomic_t when the variable is used as
> > a reference counter. This allows to avoid accidental
> > refcounter overflows that might lead to use-after-free
> > situations.
> >
> > Signed-off-by: Eric Dumazet <edumazet@google.com>
> > ---
> >  include/linux/skbuff.h | 5 +++--
> >  net/core/skbuff.c      | 8 ++++----
> >  2 files changed, 7 insertions(+), 6 deletions(-)
> >
> > diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> > index 7594e19bce622a38dc39c054093c3da15b99b67b..316a92b45351f53709886ee0099cbc83b66f1b15 100644
> > --- a/include/linux/skbuff.h
> > +++ b/include/linux/skbuff.h
> > @@ -22,6 +22,7 @@
> >  #include <linux/cache.h>
> >  #include <linux/rbtree.h>
> >  #include <linux/socket.h>
> > +#include <linux/refcount.h>
> >
> >  #include <linux/atomic.h>
> >  #include <asm/types.h>
> > @@ -456,7 +457,7 @@ struct ubuf_info {
> >                         u32 bytelen;
> >                 };
> >         };
> > -       atomic_t refcnt;
> > +       refcount_t refcnt;
> >
> >         struct mmpin {
> >                 struct user_struct *user;
> > @@ -472,7 +473,7 @@ struct ubuf_info *sock_zerocopy_realloc(struct sock *sk, size_t size,
> >
> >  static inline void sock_zerocopy_get(struct ubuf_info *uarg)
> >  {
> > -       atomic_inc(&uarg->refcnt);
> > +       refcount_inc(&uarg->refcnt);
> >  }
> >
> >  void sock_zerocopy_put(struct ubuf_info *uarg);
> > diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> > index 65b9ca3945f8fd2b1bef4aef5dd774be04e5d128..ed86ca9afd9d8d1ac47983acf6006c179285a612 100644
> > --- a/net/core/skbuff.c
> > +++ b/net/core/skbuff.c
> > @@ -963,7 +963,7 @@ struct ubuf_info *sock_zerocopy_alloc(struct sock *sk, size_t size)
> >         uarg->len = 1;
> >         uarg->bytelen = size;
> >         uarg->zerocopy = 1;
> > -       atomic_set(&uarg->refcnt, 1);
> > +       refcount_set(&uarg->refcnt, 1);
> >         sock_hold(sk);
> >
> >         return uarg;
> > @@ -1086,7 +1086,7 @@ EXPORT_SYMBOL_GPL(sock_zerocopy_callback);
> >
> >  void sock_zerocopy_put(struct ubuf_info *uarg)
> >  {
> > -       if (uarg && atomic_dec_and_test(&uarg->refcnt)) {
> > +       if (uarg && refcount_dec_and_test(&uarg->refcnt)) {
> >                 if (uarg->callback)
> >                         uarg->callback(uarg, uarg->zerocopy);
> >                 else
> > @@ -1108,7 +1108,7 @@ void sock_zerocopy_put_abort(struct ubuf_info *uarg)
> >                  * avoid an skb send inside the main loop triggering uarg free.
> >                  */
> >                 if (sk->sk_type != SOCK_STREAM)
> > -                       atomic_inc(&uarg->refcnt);
> > +                       refcount_inc(&uarg->refcnt);
> 
> This would be a 0 -> 1 transition. It is taken only on the error path from
> a socket that does not take an explicit hold at the start of sendmsg.
> 

Arg.

> The code is vestigial, really, as the final patchset only includes tcp.
> It is safe to leave as is for now, or I can remove it.
> 

OK I probably should remove this chunk in patch 1/2 then.

> In 1f8b977ab32d ("sock: enable MSG_ZEROCOPY") I also updated
> other users of ubuf_info to initialize refcnt. We probably also want to
> convert the call in handle_tx in drivers/vhost/net.c.

Thanks ! :)

Re: [PATCH net-next 2/2] net: convert (struct ubuf_info)->refcnt to refcount_t

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 11970 bytes --]

Hi Eric,

[auto build test WARNING on net-next/master]

url:    https://github.com/0day-ci/linux/commits/Eric-Dumazet/net-ubuf_info-refcnt-conversion/20170903-043506
config: i386-randconfig-i1-201736 (attached as .config)
compiler: gcc-4.8 (Debian 4.8.4-1) 4.8.4
reproduce:
        # save the attached .config to linux build tree
        make ARCH=i386 

All warnings (new ones prefixed by >>):

   drivers//vhost/net.c: In function 'handle_tx':
>> drivers//vhost/net.c:536:4: warning: passing argument 1 of 'atomic_set' from incompatible pointer type [enabled by default]
       atomic_set(&ubuf->refcnt, 1);
       ^
   In file included from include/linux/atomic.h:4:0,
                    from arch/x86/include/asm/thread_info.h:53,
                    from include/linux/thread_info.h:37,
                    from arch/x86/include/asm/preempt.h:6,
                    from include/linux/preempt.h:80,
                    from include/linux/spinlock.h:50,
                    from include/linux/wait.h:8,
                    from include/linux/eventfd.h:12,
                    from drivers//vhost/net.c:10:
   arch/x86/include/asm/atomic.h:36:29: note: expected 'struct atomic_t *' but argument is of type 'struct refcount_t *'
    static __always_inline void atomic_set(atomic_t *v, int i)
                                ^

vim +/atomic_set +536 drivers//vhost/net.c

0ed005ce0 Jason Wang         2017-01-18  442  
3a4d5c94e Michael S. Tsirkin 2010-01-14  443  /* Expects to be always run from workqueue - which acts as
3a4d5c94e Michael S. Tsirkin 2010-01-14  444   * read-size critical section for our kind of RCU. */
3a4d5c94e Michael S. Tsirkin 2010-01-14  445  static void handle_tx(struct vhost_net *net)
3a4d5c94e Michael S. Tsirkin 2010-01-14  446  {
2839400f8 Asias He           2013-04-27  447  	struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
81f95a558 Michael S. Tsirkin 2013-04-28  448  	struct vhost_virtqueue *vq = &nvq->vq;
98a527aac Al Viro            2014-12-10  449  	unsigned out, in;
d5675bd20 Michael S. Tsirkin 2010-06-24  450  	int head;
3a4d5c94e Michael S. Tsirkin 2010-01-14  451  	struct msghdr msg = {
3a4d5c94e Michael S. Tsirkin 2010-01-14  452  		.msg_name = NULL,
3a4d5c94e Michael S. Tsirkin 2010-01-14  453  		.msg_namelen = 0,
3a4d5c94e Michael S. Tsirkin 2010-01-14  454  		.msg_control = NULL,
3a4d5c94e Michael S. Tsirkin 2010-01-14  455  		.msg_controllen = 0,
3a4d5c94e Michael S. Tsirkin 2010-01-14  456  		.msg_flags = MSG_DONTWAIT,
3a4d5c94e Michael S. Tsirkin 2010-01-14  457  	};
3a4d5c94e Michael S. Tsirkin 2010-01-14  458  	size_t len, total_len = 0;
70181d512 Jason Wang         2013-04-10  459  	int err;
3a4d5c94e Michael S. Tsirkin 2010-01-14  460  	size_t hdr_size;
28457ee69 Arnd Bergmann      2010-03-09  461  	struct socket *sock;
fe729a57c Asias He           2013-05-06  462  	struct vhost_net_ubuf_ref *uninitialized_var(ubufs);
cedb9bdce Michael S. Tsirkin 2012-12-06  463  	bool zcopy, zcopy_used;
28457ee69 Arnd Bergmann      2010-03-09  464  
2e26af79b Asias He           2013-05-07  465  	mutex_lock(&vq->mutex);
2e26af79b Asias He           2013-05-07  466  	sock = vq->private_data;
3a4d5c94e Michael S. Tsirkin 2010-01-14  467  	if (!sock)
2e26af79b Asias He           2013-05-07  468  		goto out;
3a4d5c94e Michael S. Tsirkin 2010-01-14  469  
6b1e6cc78 Jason Wang         2016-06-23  470  	if (!vq_iotlb_prefetch(vq))
6b1e6cc78 Jason Wang         2016-06-23  471  		goto out;
6b1e6cc78 Jason Wang         2016-06-23  472  
8ea8cf89e Michael S. Tsirkin 2011-05-20  473  	vhost_disable_notify(&net->dev, vq);
3a4d5c94e Michael S. Tsirkin 2010-01-14  474  
81f95a558 Michael S. Tsirkin 2013-04-28  475  	hdr_size = nvq->vhost_hlen;
2839400f8 Asias He           2013-04-27  476  	zcopy = nvq->ubufs;
3a4d5c94e Michael S. Tsirkin 2010-01-14  477  
3a4d5c94e Michael S. Tsirkin 2010-01-14  478  	for (;;) {
bab632d69 Michael S. Tsirkin 2011-07-18  479  		/* Release DMAs done buffers first */
bab632d69 Michael S. Tsirkin 2011-07-18  480  		if (zcopy)
eaae8132e Michael S. Tsirkin 2012-11-01  481  			vhost_zerocopy_signal_used(net, vq);
bab632d69 Michael S. Tsirkin 2011-07-18  482  
f7c6be404 Jason Wang         2013-09-02  483  		/* If more outstanding DMAs, queue the work.
f7c6be404 Jason Wang         2013-09-02  484  		 * Handle upend_idx wrap around
f7c6be404 Jason Wang         2013-09-02  485  		 */
0ed005ce0 Jason Wang         2017-01-18  486  		if (unlikely(vhost_exceeds_maxpend(net)))
f7c6be404 Jason Wang         2013-09-02  487  			break;
f7c6be404 Jason Wang         2013-09-02  488  
030881372 Jason Wang         2016-03-04  489  		head = vhost_net_tx_get_vq_desc(net, vq, vq->iov,
3a4d5c94e Michael S. Tsirkin 2010-01-14  490  						ARRAY_SIZE(vq->iov),
030881372 Jason Wang         2016-03-04  491  						&out, &in);
d5675bd20 Michael S. Tsirkin 2010-06-24  492  		/* On error, stop handling until the next kick. */
7b3384fc3 Michael S. Tsirkin 2010-07-01  493  		if (unlikely(head < 0))
d5675bd20 Michael S. Tsirkin 2010-06-24  494  			break;
3a4d5c94e Michael S. Tsirkin 2010-01-14  495  		/* Nothing new?  Wait for eventfd to tell us they refilled. */
3a4d5c94e Michael S. Tsirkin 2010-01-14  496  		if (head == vq->num) {
8ea8cf89e Michael S. Tsirkin 2011-05-20  497  			if (unlikely(vhost_enable_notify(&net->dev, vq))) {
8ea8cf89e Michael S. Tsirkin 2011-05-20  498  				vhost_disable_notify(&net->dev, vq);
3a4d5c94e Michael S. Tsirkin 2010-01-14  499  				continue;
3a4d5c94e Michael S. Tsirkin 2010-01-14  500  			}
3a4d5c94e Michael S. Tsirkin 2010-01-14  501  			break;
3a4d5c94e Michael S. Tsirkin 2010-01-14  502  		}
3a4d5c94e Michael S. Tsirkin 2010-01-14  503  		if (in) {
3a4d5c94e Michael S. Tsirkin 2010-01-14  504  			vq_err(vq, "Unexpected descriptor format for TX: "
3a4d5c94e Michael S. Tsirkin 2010-01-14  505  			       "out %d, int %d\n", out, in);
3a4d5c94e Michael S. Tsirkin 2010-01-14  506  			break;
3a4d5c94e Michael S. Tsirkin 2010-01-14  507  		}
3a4d5c94e Michael S. Tsirkin 2010-01-14  508  		/* Skip header. TODO: support TSO. */
3a4d5c94e Michael S. Tsirkin 2010-01-14  509  		len = iov_length(vq->iov, out);
c0371da60 Al Viro            2014-11-24  510  		iov_iter_init(&msg.msg_iter, WRITE, vq->iov, out, len);
98a527aac Al Viro            2014-12-10  511  		iov_iter_advance(&msg.msg_iter, hdr_size);
3a4d5c94e Michael S. Tsirkin 2010-01-14  512  		/* Sanity check */
01e97e651 Al Viro            2014-12-15  513  		if (!msg_data_left(&msg)) {
3a4d5c94e Michael S. Tsirkin 2010-01-14  514  			vq_err(vq, "Unexpected header len for TX: "
3a4d5c94e Michael S. Tsirkin 2010-01-14  515  			       "%zd expected %zd\n",
98a527aac Al Viro            2014-12-10  516  			       len, hdr_size);
3a4d5c94e Michael S. Tsirkin 2010-01-14  517  			break;
3a4d5c94e Michael S. Tsirkin 2010-01-14  518  		}
01e97e651 Al Viro            2014-12-15  519  		len = msg_data_left(&msg);
ce21a0291 Jason Wang         2013-09-02  520  
ce21a0291 Jason Wang         2013-09-02  521  		zcopy_used = zcopy && len >= VHOST_GOODCOPY_LEN
ce21a0291 Jason Wang         2013-09-02  522  				   && (nvq->upend_idx + 1) % UIO_MAXIOV !=
ce21a0291 Jason Wang         2013-09-02  523  				      nvq->done_idx
ce21a0291 Jason Wang         2013-09-02  524  				   && vhost_net_tx_select_zcopy(net);
cedb9bdce Michael S. Tsirkin 2012-12-06  525  
bab632d69 Michael S. Tsirkin 2011-07-18  526  		/* use msg_control to pass vhost zerocopy ubuf info to skb */
cedb9bdce Michael S. Tsirkin 2012-12-06  527  		if (zcopy_used) {
46aa92d1b Michael S. Tsirkin 2013-03-17  528  			struct ubuf_info *ubuf;
2839400f8 Asias He           2013-04-27  529  			ubuf = nvq->ubuf_info + nvq->upend_idx;
bab632d69 Michael S. Tsirkin 2011-07-18  530  
8b38694a2 Michael S. Tsirkin 2014-10-24  531  			vq->heads[nvq->upend_idx].id = cpu_to_vhost32(vq, head);
ce21a0291 Jason Wang         2013-09-02  532  			vq->heads[nvq->upend_idx].len = VHOST_DMA_IN_PROGRESS;
bab632d69 Michael S. Tsirkin 2011-07-18  533  			ubuf->callback = vhost_zerocopy_callback;
2839400f8 Asias He           2013-04-27  534  			ubuf->ctx = nvq->ubufs;
2839400f8 Asias He           2013-04-27  535  			ubuf->desc = nvq->upend_idx;
1f8b977ab Willem de Bruijn   2017-08-03 @536  			atomic_set(&ubuf->refcnt, 1);
bab632d69 Michael S. Tsirkin 2011-07-18  537  			msg.msg_control = ubuf;
bab632d69 Michael S. Tsirkin 2011-07-18  538  			msg.msg_controllen = sizeof(ubuf);
2839400f8 Asias He           2013-04-27  539  			ubufs = nvq->ubufs;
0ad8b480d Michael S. Tsirkin 2014-02-13  540  			atomic_inc(&ubufs->refcount);
2839400f8 Asias He           2013-04-27  541  			nvq->upend_idx = (nvq->upend_idx + 1) % UIO_MAXIOV;
ce21a0291 Jason Wang         2013-09-02  542  		} else {
4364d5f96 Jason Wang         2013-06-05  543  			msg.msg_control = NULL;
ce21a0291 Jason Wang         2013-09-02  544  			ubufs = NULL;
ce21a0291 Jason Wang         2013-09-02  545  		}
0ed005ce0 Jason Wang         2017-01-18  546  
0ed005ce0 Jason Wang         2017-01-18  547  		total_len += len;
0ed005ce0 Jason Wang         2017-01-18  548  		if (total_len < VHOST_NET_WEIGHT &&
0ed005ce0 Jason Wang         2017-01-18  549  		    !vhost_vq_avail_empty(&net->dev, vq) &&
0ed005ce0 Jason Wang         2017-01-18  550  		    likely(!vhost_exceeds_maxpend(net))) {
0ed005ce0 Jason Wang         2017-01-18  551  			msg.msg_flags |= MSG_MORE;
0ed005ce0 Jason Wang         2017-01-18  552  		} else {
0ed005ce0 Jason Wang         2017-01-18  553  			msg.msg_flags &= ~MSG_MORE;
0ed005ce0 Jason Wang         2017-01-18  554  		}
0ed005ce0 Jason Wang         2017-01-18  555  
3a4d5c94e Michael S. Tsirkin 2010-01-14  556  		/* TODO: Check specific error and bomb out unless ENOBUFS? */
1b7841404 Ying Xue           2015-03-02  557  		err = sock->ops->sendmsg(sock, &msg, len);
3a4d5c94e Michael S. Tsirkin 2010-01-14  558  		if (unlikely(err < 0)) {
cedb9bdce Michael S. Tsirkin 2012-12-06  559  			if (zcopy_used) {
fe729a57c Asias He           2013-05-06  560  				vhost_net_ubuf_put(ubufs);
2839400f8 Asias He           2013-04-27  561  				nvq->upend_idx = ((unsigned)nvq->upend_idx - 1)
2839400f8 Asias He           2013-04-27  562  					% UIO_MAXIOV;
bab632d69 Michael S. Tsirkin 2011-07-18  563  			}
8dd014adf David Stevens      2010-07-27  564  			vhost_discard_vq_desc(vq, 1);
3a4d5c94e Michael S. Tsirkin 2010-01-14  565  			break;
3a4d5c94e Michael S. Tsirkin 2010-01-14  566  		}
3a4d5c94e Michael S. Tsirkin 2010-01-14  567  		if (err != len)
95c0ec6a9 Michael S. Tsirkin 2010-06-24  568  			pr_debug("Truncated TX packet: "
3a4d5c94e Michael S. Tsirkin 2010-01-14  569  				 " len %d != %zd\n", err, len);
cedb9bdce Michael S. Tsirkin 2012-12-06  570  		if (!zcopy_used)
3a4d5c94e Michael S. Tsirkin 2010-01-14  571  			vhost_add_used_and_signal(&net->dev, vq, head, 0);
c8fb217af Jason Wang         2012-05-02  572  		else
eaae8132e Michael S. Tsirkin 2012-11-01  573  			vhost_zerocopy_signal_used(net, vq);
eaae8132e Michael S. Tsirkin 2012-11-01  574  		vhost_net_tx_packet(net);
3a4d5c94e Michael S. Tsirkin 2010-01-14  575  		if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
3a4d5c94e Michael S. Tsirkin 2010-01-14  576  			vhost_poll_queue(&vq->poll);
3a4d5c94e Michael S. Tsirkin 2010-01-14  577  			break;
3a4d5c94e Michael S. Tsirkin 2010-01-14  578  		}
3a4d5c94e Michael S. Tsirkin 2010-01-14  579  	}
2e26af79b Asias He           2013-05-07  580  out:
3a4d5c94e Michael S. Tsirkin 2010-01-14  581  	mutex_unlock(&vq->mutex);
3a4d5c94e Michael S. Tsirkin 2010-01-14  582  }
3a4d5c94e Michael S. Tsirkin 2010-01-14  583  

:::::: The code at line 536 was first introduced by commit
:::::: 1f8b977ab32dc5d148f103326e80d9097f1cefb5 sock: enable MSG_ZEROCOPY

:::::: TO: Willem de Bruijn <willemb@google.com>
:::::: CC: David S. Miller <davem@davemloft.net>

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

[-- Attachment #2: .config.gz --]
[-- Type: application/gzip, Size: 32722 bytes --]

Re: [PATCH net-next 2/2] net: convert (struct ubuf_info)->refcnt to refcount_t

[Willem de Bruijn]

On Sat, Sep 2, 2017 at 5:58 PM, kbuild test robot <lkp@intel.com> wrote:
> Hi Eric,
>
> [auto build test WARNING on net-next/master]
>
> url:    https://github.com/0day-ci/linux/commits/Eric-Dumazet/net-ubuf_info-refcnt-conversion/20170903-043506
> config: i386-randconfig-i1-201736 (attached as .config)
> compiler: gcc-4.8 (Debian 4.8.4-1) 4.8.4
> reproduce:
>         # save the attached .config to linux build tree
>         make ARCH=i386
>
> All warnings (new ones prefixed by >>):
>
>    drivers//vhost/net.c: In function 'handle_tx':
>>> drivers//vhost/net.c:536:4: warning: passing argument 1 of 'atomic_set' from incompatible pointer type [enabled by default]
>        atomic_set(&ubuf->refcnt, 1);
>        ^
>    In file included from include/linux/atomic.h:4:0,
>                     from arch/x86/include/asm/thread_info.h:53,
>                     from include/linux/thread_info.h:37,
>                     from arch/x86/include/asm/preempt.h:6,
>                     from include/linux/preempt.h:80,
>                     from include/linux/spinlock.h:50,
>                     from include/linux/wait.h:8,
>                     from include/linux/eventfd.h:12,
>                     from drivers//vhost/net.c:10:
>    arch/x86/include/asm/atomic.h:36:29: note: expected 'struct atomic_t *' but argument is of type 'struct refcount_t *'
>     static __always_inline void atomic_set(atomic_t *v, int i)
>                                 ^

This is a false positive. This patch

  [net-next,2/2] net: convert (struct ubuf_info)->refcnt to refcount_t
  http://patchwork.ozlabs.org/patch/808402/

was superseded by

  [v2,net-next,2/2] net: convert (struct ubuf_info)->refcnt to refcount_t
  http://patchwork.ozlabs.org/patch/808477/

which has been merged into net-next as commit c1d1b437816f

That patch has the necessary change:

-                      atomic_set(&ubuf->refcnt, 1);
+                       refcount_set(&ubuf->refcnt, 1);

Re: [PATCH net-next 2/2] net: convert (struct ubuf_info)->refcnt to refcount_t

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 12764 bytes --]

Hi Eric,

[auto build test ERROR on net-next/master]

url:    https://github.com/0day-ci/linux/commits/Eric-Dumazet/net-ubuf_info-refcnt-conversion/20170903-043506
config: x86_64-acpi-redef (attached as .config)
compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

All errors (new ones prefixed by >>):

   drivers//vhost/net.c: In function 'handle_tx':
>> drivers//vhost/net.c:536:15: error: passing argument 1 of 'atomic_set' from incompatible pointer type [-Werror=incompatible-pointer-types]
       atomic_set(&ubuf->refcnt, 1);
                  ^
   In file included from include/linux/atomic.h:4:0,
                    from include/linux/jump_label.h:183,
                    from arch/x86/include/asm/string_64.h:5,
                    from arch/x86/include/asm/string.h:4,
                    from include/linux/string.h:18,
                    from include/linux/bitmap.h:8,
                    from include/linux/cpumask.h:11,
                    from arch/x86/include/asm/cpumask.h:4,
                    from arch/x86/include/asm/msr.h:10,
                    from arch/x86/include/asm/processor.h:20,
                    from arch/x86/include/asm/cpufeature.h:4,
                    from arch/x86/include/asm/thread_info.h:52,
                    from include/linux/thread_info.h:37,
                    from arch/x86/include/asm/preempt.h:6,
                    from include/linux/preempt.h:80,
                    from include/linux/spinlock.h:50,
                    from include/linux/seqlock.h:35,
                    from include/linux/time.h:5,
                    from include/linux/stat.h:18,
                    from include/linux/compat.h:12,
                    from drivers//vhost/net.c:9:
   arch/x86/include/asm/atomic.h:36:29: note: expected 'atomic_t * {aka struct <anonymous> *}' but argument is of type 'refcount_t * {aka struct refcount_struct *}'
    static __always_inline void atomic_set(atomic_t *v, int i)
                                ^~~~~~~~~~
   cc1: some warnings being treated as errors

vim +/atomic_set +536 drivers//vhost/net.c

0ed005ce0 Jason Wang         2017-01-18  442  
3a4d5c94e Michael S. Tsirkin 2010-01-14  443  /* Expects to be always run from workqueue - which acts as
3a4d5c94e Michael S. Tsirkin 2010-01-14  444   * read-size critical section for our kind of RCU. */
3a4d5c94e Michael S. Tsirkin 2010-01-14  445  static void handle_tx(struct vhost_net *net)
3a4d5c94e Michael S. Tsirkin 2010-01-14  446  {
2839400f8 Asias He           2013-04-27  447  	struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
81f95a558 Michael S. Tsirkin 2013-04-28  448  	struct vhost_virtqueue *vq = &nvq->vq;
98a527aac Al Viro            2014-12-10  449  	unsigned out, in;
d5675bd20 Michael S. Tsirkin 2010-06-24  450  	int head;
3a4d5c94e Michael S. Tsirkin 2010-01-14  451  	struct msghdr msg = {
3a4d5c94e Michael S. Tsirkin 2010-01-14  452  		.msg_name = NULL,
3a4d5c94e Michael S. Tsirkin 2010-01-14  453  		.msg_namelen = 0,
3a4d5c94e Michael S. Tsirkin 2010-01-14  454  		.msg_control = NULL,
3a4d5c94e Michael S. Tsirkin 2010-01-14  455  		.msg_controllen = 0,
3a4d5c94e Michael S. Tsirkin 2010-01-14  456  		.msg_flags = MSG_DONTWAIT,
3a4d5c94e Michael S. Tsirkin 2010-01-14  457  	};
3a4d5c94e Michael S. Tsirkin 2010-01-14  458  	size_t len, total_len = 0;
70181d512 Jason Wang         2013-04-10  459  	int err;
3a4d5c94e Michael S. Tsirkin 2010-01-14  460  	size_t hdr_size;
28457ee69 Arnd Bergmann      2010-03-09  461  	struct socket *sock;
fe729a57c Asias He           2013-05-06  462  	struct vhost_net_ubuf_ref *uninitialized_var(ubufs);
cedb9bdce Michael S. Tsirkin 2012-12-06  463  	bool zcopy, zcopy_used;
28457ee69 Arnd Bergmann      2010-03-09  464  
2e26af79b Asias He           2013-05-07  465  	mutex_lock(&vq->mutex);
2e26af79b Asias He           2013-05-07  466  	sock = vq->private_data;
3a4d5c94e Michael S. Tsirkin 2010-01-14  467  	if (!sock)
2e26af79b Asias He           2013-05-07  468  		goto out;
3a4d5c94e Michael S. Tsirkin 2010-01-14  469  
6b1e6cc78 Jason Wang         2016-06-23  470  	if (!vq_iotlb_prefetch(vq))
6b1e6cc78 Jason Wang         2016-06-23  471  		goto out;
6b1e6cc78 Jason Wang         2016-06-23  472  
8ea8cf89e Michael S. Tsirkin 2011-05-20  473  	vhost_disable_notify(&net->dev, vq);
3a4d5c94e Michael S. Tsirkin 2010-01-14  474  
81f95a558 Michael S. Tsirkin 2013-04-28  475  	hdr_size = nvq->vhost_hlen;
2839400f8 Asias He           2013-04-27  476  	zcopy = nvq->ubufs;
3a4d5c94e Michael S. Tsirkin 2010-01-14  477  
3a4d5c94e Michael S. Tsirkin 2010-01-14  478  	for (;;) {
bab632d69 Michael S. Tsirkin 2011-07-18  479  		/* Release DMAs done buffers first */
bab632d69 Michael S. Tsirkin 2011-07-18  480  		if (zcopy)
eaae8132e Michael S. Tsirkin 2012-11-01  481  			vhost_zerocopy_signal_used(net, vq);
bab632d69 Michael S. Tsirkin 2011-07-18  482  
f7c6be404 Jason Wang         2013-09-02  483  		/* If more outstanding DMAs, queue the work.
f7c6be404 Jason Wang         2013-09-02  484  		 * Handle upend_idx wrap around
f7c6be404 Jason Wang         2013-09-02  485  		 */
0ed005ce0 Jason Wang         2017-01-18  486  		if (unlikely(vhost_exceeds_maxpend(net)))
f7c6be404 Jason Wang         2013-09-02  487  			break;
f7c6be404 Jason Wang         2013-09-02  488  
030881372 Jason Wang         2016-03-04  489  		head = vhost_net_tx_get_vq_desc(net, vq, vq->iov,
3a4d5c94e Michael S. Tsirkin 2010-01-14  490  						ARRAY_SIZE(vq->iov),
030881372 Jason Wang         2016-03-04  491  						&out, &in);
d5675bd20 Michael S. Tsirkin 2010-06-24  492  		/* On error, stop handling until the next kick. */
7b3384fc3 Michael S. Tsirkin 2010-07-01  493  		if (unlikely(head < 0))
d5675bd20 Michael S. Tsirkin 2010-06-24  494  			break;
3a4d5c94e Michael S. Tsirkin 2010-01-14  495  		/* Nothing new?  Wait for eventfd to tell us they refilled. */
3a4d5c94e Michael S. Tsirkin 2010-01-14  496  		if (head == vq->num) {
8ea8cf89e Michael S. Tsirkin 2011-05-20  497  			if (unlikely(vhost_enable_notify(&net->dev, vq))) {
8ea8cf89e Michael S. Tsirkin 2011-05-20  498  				vhost_disable_notify(&net->dev, vq);
3a4d5c94e Michael S. Tsirkin 2010-01-14  499  				continue;
3a4d5c94e Michael S. Tsirkin 2010-01-14  500  			}
3a4d5c94e Michael S. Tsirkin 2010-01-14  501  			break;
3a4d5c94e Michael S. Tsirkin 2010-01-14  502  		}
3a4d5c94e Michael S. Tsirkin 2010-01-14  503  		if (in) {
3a4d5c94e Michael S. Tsirkin 2010-01-14  504  			vq_err(vq, "Unexpected descriptor format for TX: "
3a4d5c94e Michael S. Tsirkin 2010-01-14  505  			       "out %d, int %d\n", out, in);
3a4d5c94e Michael S. Tsirkin 2010-01-14  506  			break;
3a4d5c94e Michael S. Tsirkin 2010-01-14  507  		}
3a4d5c94e Michael S. Tsirkin 2010-01-14  508  		/* Skip header. TODO: support TSO. */
3a4d5c94e Michael S. Tsirkin 2010-01-14  509  		len = iov_length(vq->iov, out);
c0371da60 Al Viro            2014-11-24  510  		iov_iter_init(&msg.msg_iter, WRITE, vq->iov, out, len);
98a527aac Al Viro            2014-12-10  511  		iov_iter_advance(&msg.msg_iter, hdr_size);
3a4d5c94e Michael S. Tsirkin 2010-01-14  512  		/* Sanity check */
01e97e651 Al Viro            2014-12-15  513  		if (!msg_data_left(&msg)) {
3a4d5c94e Michael S. Tsirkin 2010-01-14  514  			vq_err(vq, "Unexpected header len for TX: "
3a4d5c94e Michael S. Tsirkin 2010-01-14  515  			       "%zd expected %zd\n",
98a527aac Al Viro            2014-12-10  516  			       len, hdr_size);
3a4d5c94e Michael S. Tsirkin 2010-01-14  517  			break;
3a4d5c94e Michael S. Tsirkin 2010-01-14  518  		}
01e97e651 Al Viro            2014-12-15  519  		len = msg_data_left(&msg);
ce21a0291 Jason Wang         2013-09-02  520  
ce21a0291 Jason Wang         2013-09-02  521  		zcopy_used = zcopy && len >= VHOST_GOODCOPY_LEN
ce21a0291 Jason Wang         2013-09-02  522  				   && (nvq->upend_idx + 1) % UIO_MAXIOV !=
ce21a0291 Jason Wang         2013-09-02  523  				      nvq->done_idx
ce21a0291 Jason Wang         2013-09-02  524  				   && vhost_net_tx_select_zcopy(net);
cedb9bdce Michael S. Tsirkin 2012-12-06  525  
bab632d69 Michael S. Tsirkin 2011-07-18  526  		/* use msg_control to pass vhost zerocopy ubuf info to skb */
cedb9bdce Michael S. Tsirkin 2012-12-06  527  		if (zcopy_used) {
46aa92d1b Michael S. Tsirkin 2013-03-17  528  			struct ubuf_info *ubuf;
2839400f8 Asias He           2013-04-27  529  			ubuf = nvq->ubuf_info + nvq->upend_idx;
bab632d69 Michael S. Tsirkin 2011-07-18  530  
8b38694a2 Michael S. Tsirkin 2014-10-24  531  			vq->heads[nvq->upend_idx].id = cpu_to_vhost32(vq, head);
ce21a0291 Jason Wang         2013-09-02  532  			vq->heads[nvq->upend_idx].len = VHOST_DMA_IN_PROGRESS;
bab632d69 Michael S. Tsirkin 2011-07-18  533  			ubuf->callback = vhost_zerocopy_callback;
2839400f8 Asias He           2013-04-27  534  			ubuf->ctx = nvq->ubufs;
2839400f8 Asias He           2013-04-27  535  			ubuf->desc = nvq->upend_idx;
1f8b977ab Willem de Bruijn   2017-08-03 @536  			atomic_set(&ubuf->refcnt, 1);
bab632d69 Michael S. Tsirkin 2011-07-18  537  			msg.msg_control = ubuf;
bab632d69 Michael S. Tsirkin 2011-07-18  538  			msg.msg_controllen = sizeof(ubuf);
2839400f8 Asias He           2013-04-27  539  			ubufs = nvq->ubufs;
0ad8b480d Michael S. Tsirkin 2014-02-13  540  			atomic_inc(&ubufs->refcount);
2839400f8 Asias He           2013-04-27  541  			nvq->upend_idx = (nvq->upend_idx + 1) % UIO_MAXIOV;
ce21a0291 Jason Wang         2013-09-02  542  		} else {
4364d5f96 Jason Wang         2013-06-05  543  			msg.msg_control = NULL;
ce21a0291 Jason Wang         2013-09-02  544  			ubufs = NULL;
ce21a0291 Jason Wang         2013-09-02  545  		}
0ed005ce0 Jason Wang         2017-01-18  546  
0ed005ce0 Jason Wang         2017-01-18  547  		total_len += len;
0ed005ce0 Jason Wang         2017-01-18  548  		if (total_len < VHOST_NET_WEIGHT &&
0ed005ce0 Jason Wang         2017-01-18  549  		    !vhost_vq_avail_empty(&net->dev, vq) &&
0ed005ce0 Jason Wang         2017-01-18  550  		    likely(!vhost_exceeds_maxpend(net))) {
0ed005ce0 Jason Wang         2017-01-18  551  			msg.msg_flags |= MSG_MORE;
0ed005ce0 Jason Wang         2017-01-18  552  		} else {
0ed005ce0 Jason Wang         2017-01-18  553  			msg.msg_flags &= ~MSG_MORE;
0ed005ce0 Jason Wang         2017-01-18  554  		}
0ed005ce0 Jason Wang         2017-01-18  555  
3a4d5c94e Michael S. Tsirkin 2010-01-14  556  		/* TODO: Check specific error and bomb out unless ENOBUFS? */
1b7841404 Ying Xue           2015-03-02  557  		err = sock->ops->sendmsg(sock, &msg, len);
3a4d5c94e Michael S. Tsirkin 2010-01-14  558  		if (unlikely(err < 0)) {
cedb9bdce Michael S. Tsirkin 2012-12-06  559  			if (zcopy_used) {
fe729a57c Asias He           2013-05-06  560  				vhost_net_ubuf_put(ubufs);
2839400f8 Asias He           2013-04-27  561  				nvq->upend_idx = ((unsigned)nvq->upend_idx - 1)
2839400f8 Asias He           2013-04-27  562  					% UIO_MAXIOV;
bab632d69 Michael S. Tsirkin 2011-07-18  563  			}
8dd014adf David Stevens      2010-07-27  564  			vhost_discard_vq_desc(vq, 1);
3a4d5c94e Michael S. Tsirkin 2010-01-14  565  			break;
3a4d5c94e Michael S. Tsirkin 2010-01-14  566  		}
3a4d5c94e Michael S. Tsirkin 2010-01-14  567  		if (err != len)
95c0ec6a9 Michael S. Tsirkin 2010-06-24  568  			pr_debug("Truncated TX packet: "
3a4d5c94e Michael S. Tsirkin 2010-01-14  569  				 " len %d != %zd\n", err, len);
cedb9bdce Michael S. Tsirkin 2012-12-06  570  		if (!zcopy_used)
3a4d5c94e Michael S. Tsirkin 2010-01-14  571  			vhost_add_used_and_signal(&net->dev, vq, head, 0);
c8fb217af Jason Wang         2012-05-02  572  		else
eaae8132e Michael S. Tsirkin 2012-11-01  573  			vhost_zerocopy_signal_used(net, vq);
eaae8132e Michael S. Tsirkin 2012-11-01  574  		vhost_net_tx_packet(net);
3a4d5c94e Michael S. Tsirkin 2010-01-14  575  		if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
3a4d5c94e Michael S. Tsirkin 2010-01-14  576  			vhost_poll_queue(&vq->poll);
3a4d5c94e Michael S. Tsirkin 2010-01-14  577  			break;
3a4d5c94e Michael S. Tsirkin 2010-01-14  578  		}
3a4d5c94e Michael S. Tsirkin 2010-01-14  579  	}
2e26af79b Asias He           2013-05-07  580  out:
3a4d5c94e Michael S. Tsirkin 2010-01-14  581  	mutex_unlock(&vq->mutex);
3a4d5c94e Michael S. Tsirkin 2010-01-14  582  }
3a4d5c94e Michael S. Tsirkin 2010-01-14  583  

:::::: The code at line 536 was first introduced by commit
:::::: 1f8b977ab32dc5d148f103326e80d9097f1cefb5 sock: enable MSG_ZEROCOPY

:::::: TO: Willem de Bruijn <willemb@google.com>
:::::: CC: David S. Miller <davem@davemloft.net>

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

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