From 10369080454d87ee5b2db211ce947cb3118f0e13 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@google.com>
Date: Tue, 7 Mar 2023 14:59:59 +0000
Subject: [PATCH] net: reclaim skb->scm_io_uring bit
Commit 0091bfc81741 ("io_uring/af_unix: defer registered
files gc to io_uring release") added one bit to struct sk_buff.
This structure is critical for networking, and we try very hard
to not add bloat on it, unless absolutely required.
For instance, we can use a specific destructor as a wrapper
around unix_destruct_scm(), to identify skbs that unix_gc()
has to special case.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Cc: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
include/linux/skbuff.h | 2 --
include/net/af_unix.h | 1 +
io_uring/rsrc.c | 3 +--
net/unix/garbage.c | 2 +-
net/unix/scm.c | 6 ++++++
5 files changed, 9 insertions(+), 5 deletions(-)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index ff7ad331fb825..fe661011644b8 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -810,7 +810,6 @@ typedef unsigned char *sk_buff_data_t;
* @csum_level: indicates the number of consecutive checksums found in
* the packet minus one that have been verified as
* CHECKSUM_UNNECESSARY (max 3)
- * @scm_io_uring: SKB holds io_uring registered files
* @dst_pending_confirm: need to confirm neighbour
* @decrypted: Decrypted SKB
* @slow_gro: state present at GRO time, slower prepare step required
@@ -989,7 +988,6 @@ struct sk_buff {
#endif
__u8 slow_gro:1;
__u8 csum_not_inet:1;
- __u8 scm_io_uring:1;
#ifdef CONFIG_NET_SCHED
__u16 tc_index; /* traffic control index */
diff --git a/include/net/af_unix.h b/include/net/af_unix.h
index 480fa579787e5..45ebde587138e 100644
--- a/include/net/af_unix.h
+++ b/include/net/af_unix.h
@@ -11,6 +11,7 @@
void unix_inflight(struct user_struct *user, struct file *fp);
void unix_notinflight(struct user_struct *user, struct file *fp);
void unix_destruct_scm(struct sk_buff *skb);
+void io_uring_destruct_scm(struct sk_buff *skb);
void unix_gc(void);
void wait_for_unix_gc(void);
struct sock *unix_get_socket(struct file *filp);
diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c
index a59fc02de5983..27ceda3b50cf4 100644
--- a/io_uring/rsrc.c
+++ b/io_uring/rsrc.c
@@ -867,8 +867,7 @@ int __io_scm_file_account(struct io_ring_ctx *ctx, struct file *file)
UNIXCB(skb).fp = fpl;
skb->sk = sk;
- skb->scm_io_uring = 1;
- skb->destructor = unix_destruct_scm;
+ skb->destructor = io_uring_destruct_scm;
refcount_add(skb->truesize, &sk->sk_wmem_alloc);
}
diff --git a/net/unix/garbage.c b/net/unix/garbage.c
index dc27635403932..2405f0f9af31c 100644
--- a/net/unix/garbage.c
+++ b/net/unix/garbage.c
@@ -305,7 +305,7 @@ void unix_gc(void)
* release.path eventually putting registered files.
*/
skb_queue_walk_safe(&hitlist, skb, next_skb) {
- if (skb->scm_io_uring) {
+ if (skb->destructor == io_uring_destruct_scm) {
__skb_unlink(skb, &hitlist);
skb_queue_tail(&skb->sk->sk_receive_queue, skb);
}
diff --git a/net/unix/scm.c b/net/unix/scm.c
index aa27a02478dc1..f9152881d77f6 100644
--- a/net/unix/scm.c
+++ b/net/unix/scm.c
@@ -152,3 +152,9 @@ void unix_destruct_scm(struct sk_buff *skb)
sock_wfree(skb);
}
EXPORT_SYMBOL(unix_destruct_scm);
+
+void io_uring_destruct_scm(struct sk_buff *skb)
+{
+ unix_destruct_scm(skb);
+}
+EXPORT_SYMBOL(io_uring_destruct_scm);
--
2.30.2