linux-kernel - Re: [PATCH] posix-timers: Handle returned errors poperly in [i]timer

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Date: Mon, 15 Apr 2024 15:00:24 +0200
From: Oleg Nesterov <oleg@...hat.com>
To: Anna-Maria Behnsen <anna-maria@...utronix.de>
Cc: Thomas Gleixner <tglx@...utronix.de>,
	LKML <linux-kernel@...r.kernel.org>,
	Frederic Weisbecker <frederic@...nel.org>,
	John Stultz <jstultz@...gle.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>, Stephen Boyd <sboyd@...nel.org>,
	Eric Biederman <ebiederm@...ssion.com>
Subject: Re: [PATCH] posix-timers: Handle returned errors poperly in
 [i]timer_delete()

On 04/15, Anna-Maria Behnsen wrote:
>
> timer_delete_hook() returns -EINVAL when the clock or the timer_del
> callback of the clock does not exist. This return value is not handled by
> the callsites timer_delete() and itimer_delete().

IIUC this shouldn't happen? timer_delete_hook() WARN()s in this case,
not sure we need to return this error to userspace...

> --- a/kernel/time/posix-timers.c
> +++ b/kernel/time/posix-timers.c
> @@ -1009,6 +1009,7 @@ SYSCALL_DEFINE1(timer_delete, timer_t, t
>  {
>  	struct k_itimer *timer;
>  	unsigned long flags;
> +	int ret;
>  
>  	timer = lock_timer(timer_id, &flags);
>  
> @@ -1019,7 +1020,11 @@ SYSCALL_DEFINE1(timer_delete, timer_t, t
>  	/* Prevent signal delivery and rearming. */
>  	timer->it_signal_seq++;
>  
> -	if (unlikely(timer_delete_hook(timer) == TIMER_RETRY)) {
> +	ret = timer_delete_hook(timer);
> +	if (ret < 0)
> +		return ret;

unlock_timer() ?

>  static void itimer_delete(struct k_itimer *timer)
>  {
>  	unsigned long flags;
> +	int ret;
>  
>  	/*
>  	 * irqsave is required to make timer_wait_running() work.
> @@ -1054,13 +1060,17 @@ static void itimer_delete(struct k_itime
>  	spin_lock_irqsave(&timer->it_lock, flags);
>  
>  retry_delete:
> +	ret = timer_delete_hook(timer);
> +	if (WARN_ON_ONCE(ret < 0))
> +		return;

the same.

Oleg.