This is a note to let you know that I've just added the patch titled
af_unix: Do not use atomic ops for unix_sk(sk)->inflight.
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
af_unix-do-not-use-atomic-ops-for-unix_sk-sk-infligh.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 695a051e1b37cea28ccda99978ca41a17e3d1738
Author: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Date: Tue Jan 23 09:08:53 2024 -0800
af_unix: Do not use atomic ops for unix_sk(sk)->inflight.
[ Upstream commit 97af84a6bba2ab2b9c704c08e67de3b5ea551bb2 ]
When touching unix_sk(sk)->inflight, we are always under
spin_lock(&unix_gc_lock).
Let's convert unix_sk(sk)->inflight to the normal unsigned long.
Signed-off-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Reviewed-by: Simon Horman <horms@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240123170856.41348-3-kuniyu@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Stable-dep-of: 47d8ac011fe1 ("af_unix: Fix garbage collector racing against connect()")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/include/net/af_unix.h b/include/net/af_unix.h
index afd40dce40f3d..d1b07ddbe677e 100644
--- a/include/net/af_unix.h
+++ b/include/net/af_unix.h
@@ -55,7 +55,7 @@ struct unix_sock {
struct mutex iolock, bindlock;
struct sock *peer;
struct list_head link;
- atomic_long_t inflight;
+ unsigned long inflight;
spinlock_t lock;
unsigned long gc_flags;
#define UNIX_GC_CANDIDATE 0
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index ac3d4b540c100..918724844231e 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -992,11 +992,11 @@ static struct sock *unix_create1(struct net *net, struct socket *sock, int kern,
sk->sk_write_space = unix_write_space;
sk->sk_max_ack_backlog = net->unx.sysctl_max_dgram_qlen;
sk->sk_destruct = unix_sock_destructor;
- u = unix_sk(sk);
+ u = unix_sk(sk);
+ u->inflight = 0;
u->path.dentry = NULL;
u->path.mnt = NULL;
spin_lock_init(&u->lock);
- atomic_long_set(&u->inflight, 0);
INIT_LIST_HEAD(&u->link);
mutex_init(&u->iolock); /* single task reading lock */
mutex_init(&u->bindlock); /* single task binding lock */
diff --git a/net/unix/garbage.c b/net/unix/garbage.c
index 027c86e804f8a..aea222796dfdc 100644
--- a/net/unix/garbage.c
+++ b/net/unix/garbage.c
@@ -166,17 +166,18 @@ static void scan_children(struct sock *x, void (*func)(struct unix_sock *),
static void dec_inflight(struct unix_sock *usk)
{
- atomic_long_dec(&usk->inflight);
+ usk->inflight--;
}
static void inc_inflight(struct unix_sock *usk)
{
- atomic_long_inc(&usk->inflight);
+ usk->inflight++;
}
static void inc_inflight_move_tail(struct unix_sock *u)
{
- atomic_long_inc(&u->inflight);
+ u->inflight++;
+
/* If this still might be part of a cycle, move it to the end
* of the list, so that it's checked even if it was already
* passed over
@@ -237,14 +238,12 @@ void unix_gc(void)
*/
list_for_each_entry_safe(u, next, &gc_inflight_list, link) {
long total_refs;
- long inflight_refs;
total_refs = file_count(u->sk.sk_socket->file);
- inflight_refs = atomic_long_read(&u->inflight);
- BUG_ON(inflight_refs < 1);
- BUG_ON(total_refs < inflight_refs);
- if (total_refs == inflight_refs) {
+ BUG_ON(!u->inflight);
+ BUG_ON(total_refs < u->inflight);
+ if (total_refs == u->inflight) {
list_move_tail(&u->link, &gc_candidates);
__set_bit(UNIX_GC_CANDIDATE, &u->gc_flags);
__set_bit(UNIX_GC_MAYBE_CYCLE, &u->gc_flags);
@@ -271,7 +270,7 @@ void unix_gc(void)
/* Move cursor to after the current position. */
list_move(&cursor, &u->link);
- if (atomic_long_read(&u->inflight) > 0) {
+ if (u->inflight) {
list_move_tail(&u->link, ¬_cycle_list);
__clear_bit(UNIX_GC_MAYBE_CYCLE, &u->gc_flags);
scan_children(&u->sk, inc_inflight_move_tail, NULL);
diff --git a/net/unix/scm.c b/net/unix/scm.c
index 822ce0d0d7915..e92f2fad64105 100644
--- a/net/unix/scm.c
+++ b/net/unix/scm.c
@@ -53,12 +53,13 @@ void unix_inflight(struct user_struct *user, struct file *fp)
if (s) {
struct unix_sock *u = unix_sk(s);
- if (atomic_long_inc_return(&u->inflight) == 1) {
+ if (!u->inflight) {
BUG_ON(!list_empty(&u->link));
list_add_tail(&u->link, &gc_inflight_list);
} else {
BUG_ON(list_empty(&u->link));
}
+ u->inflight++;
/* Paired with READ_ONCE() in wait_for_unix_gc() */
WRITE_ONCE(unix_tot_inflight, unix_tot_inflight + 1);
}
@@ -75,10 +76,11 @@ void unix_notinflight(struct user_struct *user, struct file *fp)
if (s) {
struct unix_sock *u = unix_sk(s);
- BUG_ON(!atomic_long_read(&u->inflight));
+ BUG_ON(!u->inflight);
BUG_ON(list_empty(&u->link));
- if (atomic_long_dec_and_test(&u->inflight))
+ u->inflight--;
+ if (!u->inflight)
list_del_init(&u->link);
/* Paired with READ_ONCE() in wait_for_unix_gc() */
WRITE_ONCE(unix_tot_inflight, unix_tot_inflight - 1);
