diff options
| author | Mark Johnston <markj@FreeBSD.org> | 2026-07-07 22:52:56 +0000 |
|---|---|---|
| committer | Mark Johnston <markj@FreeBSD.org> | 2026-07-07 23:28:55 +0000 |
| commit | 407c7c339adb429efcb6658accd16399031c34ca (patch) | |
| tree | e65c209af96885a9355302ca677d96464a496295 | |
| parent | 23e94b040b9b99f097c113fc8576576ffec0486f (diff) | |
linux/futex: Don't load a timeout when try-locking a mutex
linux_sys_futex() does not copyin a timespec for the timeout if the
operation is LINUX_FUTEX_TRYLOCK_PI, presumably because it doesn't make
sense to specify a timeout for a try-lock operation. However, this
means that we pass a userspace timespec pointer to
linux_umtx_abs_timeout_init().
Modify linux_futex_lock_pi() to not initialize the timeout if we're
try-locking.
Reviewed by: kib, dchagin
Reported by: Yuxiang Yang, Yizhou Zhao, Ao Wang, Xuewei Feng, Qi Li,
and Ke Xu from Tsinghua University using GLM-5.2 from Z.ai
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D58061
| -rw-r--r-- | sys/compat/linux/linux_futex.c | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/sys/compat/linux/linux_futex.c b/sys/compat/linux/linux_futex.c index 0586eb55a8f3..2e26fb6458a3 100644 --- a/sys/compat/linux/linux_futex.c +++ b/sys/compat/linux/linux_futex.c @@ -356,7 +356,7 @@ linux_futex(struct thread *td, struct linux_futex_args *args) static int linux_futex_lock_pi(struct thread *td, bool try, struct linux_futex_args *args) { - struct umtx_abs_timeout timo; + struct umtx_abs_timeout timo, *timop; struct linux_emuldata *em; struct umtx_pi *pi, *new_pi; struct thread *td1; @@ -370,8 +370,12 @@ linux_futex_lock_pi(struct thread *td, bool try, struct linux_futex_args *args) &uq->uq_key); if (error != 0) return (error); - if (args->ts != NULL) - linux_umtx_abs_timeout_init(&timo, args); + if (!try && args->ts != NULL) { + timop = &timo; + linux_umtx_abs_timeout_init(timop, args); + } else { + timop = NULL; + } umtxq_lock(&uq->uq_key); pi = umtx_pi_lookup(&uq->uq_key); @@ -546,8 +550,7 @@ linux_futex_lock_pi(struct thread *td, bool try, struct linux_futex_args *args) /* We set the contested bit, sleep. */ error = umtxq_sleep_pi(uq, pi, owner, "futexp", - args->ts == NULL ? NULL : &timo, - (args->flags & FUTEX_SHARED) != 0); + timop, (args->flags & FUTEX_SHARED) != 0); if (error != 0) continue; |