February 28, 2026 at 18:43, "Eric Dumazet" <edumazet@google.com mailto:edumazet@google.com?to=%22Eric%20Dumazet%22%20%3Cedumazet%40google.com%3E > wrote:

On Sat, Feb 28, 2026 at 10:07 AM Jiayuan Chen [off-list ref] wrote:

quoted

From: Jiayuan Chen <redacted>

 When CONFIG_PREEMPT_RT is enabled, __SPIN_LOCK_UNLOCKED() expands to a
 brace-enclosed initializer rather than a compound literal, which cannot
 be used in assignment expressions. This causes a build failure:

 net/core/sock.c:3787:29: error: expected expression before '{' token
 3787 | tmp.slock = __SPIN_LOCK_UNLOCKED(tmp.slock);

 Use declaration-with-initializer instead of assignment, consistent with
 how __SPIN_LOCK_UNLOCKED() is used elsewhere in the kernel (e.g.
 DEFINE_SPINLOCK).

 Fixes: 5151ec54f586 ("net: use try_cmpxchg() in lock_sock_nested()")
 Signed-off-by: Jiayuan Chen [off-list ref]
 ---
 net/core/sock.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

 diff --git a/net/core/sock.c b/net/core/sock.c
 index 9d841975a7a1..2461aba7b18a 100644
 --- a/net/core/sock.c
 +++ b/net/core/sock.c
 @@ -3782,12 +3782,10 @@ void noinline lock_sock_nested(struct sock *sk, int subclass)
 might_sleep();
 #ifdef CONFIG_64BIT
 if (sizeof(struct slock_owned) == sizeof(long)) {
 - socket_lock_t tmp, old;
 -
 - tmp.slock = __SPIN_LOCK_UNLOCKED(tmp.slock);
 - tmp.owned = 1;
 - old.slock = __SPIN_LOCK_UNLOCKED(old.slock);
 - old.owned = 0;
 + socket_lock_t tmp = { .slock = __SPIN_LOCK_UNLOCKED(tmp.slock),
 + .owned = 1 };
 + socket_lock_t old = { .slock = __SPIN_LOCK_UNLOCKED(old.slock),
 + .owned = 0 };
 if (likely(try_cmpxchg(&sk->sk_lock.combined,
 &old.combined, tmp.combined)))
 return;

Thanks for your patch, could you please use a nicer formatting ?
(And keep an empty line between variables and code)

Ack. I will send it later.