linux-kernel - [RFC net-next v3 03/29] skbuff: add SKBFL_DONT

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Message-Id: <1def15f02ef8bcfe9fd80a4accd3c5af57675179.1653992701.git.asml.silence@gmail.com>
Date:   Tue, 28 Jun 2022 19:56:25 +0100
From:   Pavel Begunkov <asml.silence@...il.com>
To:     io-uring@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Jonathan Lemon <jonathan.lemon@...il.com>,
        Willem de Bruijn <willemb@...gle.com>,
        Jens Axboe <axboe@...nel.dk>, kernel-team@...com,
        Pavel Begunkov <asml.silence@...il.com>
Subject: [RFC net-next v3 03/29] skbuff: add SKBFL_DONT_ORPHAN flag

We don't want to list every single ubuf_info callback in
skb_orphan_frags(), add a flag controlling the behaviour.

Signed-off-by: Pavel Begunkov <asml.silence@...il.com>
---
 include/linux/skbuff.h | 8 +++++---
 net/core/skbuff.c      | 2 +-
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index da96f0d3e753..eead3527bdaf 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -686,10 +686,13 @@ enum {
 	 * charged to the kernel memory.
 	 */
 	SKBFL_PURE_ZEROCOPY = BIT(2),
+
+	SKBFL_DONT_ORPHAN = BIT(3),
 };
 
 #define SKBFL_ZEROCOPY_FRAG	(SKBFL_ZEROCOPY_ENABLE | SKBFL_SHARED_FRAG)
-#define SKBFL_ALL_ZEROCOPY	(SKBFL_ZEROCOPY_FRAG | SKBFL_PURE_ZEROCOPY)
+#define SKBFL_ALL_ZEROCOPY	(SKBFL_ZEROCOPY_FRAG | SKBFL_PURE_ZEROCOPY | \
+				 SKBFL_DONT_ORPHAN)
 
 /*
  * The callback notifies userspace to release buffers when skb DMA is done in
@@ -3175,8 +3178,7 @@ static inline int skb_orphan_frags(struct sk_buff *skb, gfp_t gfp_mask)
 {
 	if (likely(!skb_zcopy(skb)))
 		return 0;
-	if (!skb_zcopy_is_nouarg(skb) &&
-	    skb_uarg(skb)->callback == msg_zerocopy_callback)
+	if (skb_shinfo(skb)->flags & SKBFL_DONT_ORPHAN)
 		return 0;
 	return skb_copy_ubufs(skb, gfp_mask);
 }
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 5b3559cb1d82..5b35791064d1 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -1193,7 +1193,7 @@ static struct ubuf_info *msg_zerocopy_alloc(struct sock *sk, size_t size)
 	uarg->len = 1;
 	uarg->bytelen = size;
 	uarg->zerocopy = 1;
-	uarg->flags = SKBFL_ZEROCOPY_FRAG;
+	uarg->flags = SKBFL_ZEROCOPY_FRAG | SKBFL_DONT_ORPHAN;
 	refcount_set(&uarg->refcnt, 1);
 	sock_hold(sk);
 
-- 
2.36.1