From a73d7f98e41a96d6e1bcb0e731ab185d9d67878e Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Sat, 4 Jul 2026 13:09:36 +0200 Subject: [PATCH] posix-cpu-timers: Don't abuse lock_task_sighand() in handle_posix_cpu_timers() After commit f90fff1e152d ("posix-cpu-timers: fix race between handle_posix_cpu_timers() and posix_cpu_timer_del()"), tsk->sighand is stable in handle_posix_cpu_timers(), so it can use the plain spin_lock_irqsave(&tsk->sighand->siglock). Signed-off-by: Oleg Nesterov Signed-off-by: Thomas Gleixner Reviewed-by: Bradley Morgan Link: https://patch.msgid.link/akjp8AGpY8eJG5I1@redhat.com --- kernel/time/posix-cpu-timers.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c index 5e633d8750d1..c8a9b52cc937 100644 --- a/kernel/time/posix-cpu-timers.c +++ b/kernel/time/posix-cpu-timers.c @@ -1300,8 +1300,11 @@ static void handle_posix_cpu_timers(struct task_struct *tsk) unsigned long flags, start; LIST_HEAD(firing); - if (!lock_task_sighand(tsk, &flags)) - return; + /* + * tsk is current and ->sighand is stable, see the + * tsk->exit_state check in run_posix_cpu_timers() + */ + spin_lock_irqsave(&tsk->sighand->siglock, flags); do { /* @@ -1361,7 +1364,7 @@ static void handle_posix_cpu_timers(struct task_struct *tsk) * that gets the timer lock before we do will give it up and * spin until we've taken care of that timer below. */ - unlock_task_sighand(tsk, &flags); + spin_unlock_irqrestore(&tsk->sighand->siglock, flags); /* * Now that all the timers on our list have the firing flag,