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Date: Sat, 8 Mar 2025 00:03:44 +0100
From: Frederic Weisbecker <frederic@kernel.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Anna-Maria Behnsen <anna-maria@linutronix.de>,
	Benjamin Segall <bsegall@google.com>,
	Eric Dumazet <edumazet@google.com>,
	Andrey Vagin <avagin@openvz.org>,
	Pavel Tikhomirov <ptikhomirov@virtuozzo.com>,
	Peter Zijlstra <peterz@infradead.org>
Subject: Re: [patch V2 08/17] posix-timers: Rework timer removal
Message-ID: <Z8t7UJUd9SLT0Ytj@pavilion.home>
References: <20250302185753.311903554@linutronix.de>
 <20250302193627.416552300@linutronix.de>
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In-Reply-To: <20250302193627.416552300@linutronix.de>

Le Sun, Mar 02, 2025 at 08:36:56PM +0100, Thomas Gleixner a écrit :
> --- a/include/linux/posix-timers.h
> +++ b/include/linux/posix-timers.h
> @@ -240,6 +240,13 @@ static inline void posixtimer_sigqueue_p
>  
>  	posixtimer_putref(tmr);
>  }
> +
> +static inline bool posixtimer_valid(const struct k_itimer *timer)
> +{
> +	unsigned long val = (unsigned long)timer->it_signal;
> +
> +	return !(val & 0x1UL);
> +}
>  #else  /* CONFIG_POSIX_TIMERS */
>  static inline void posixtimer_sigqueue_getref(struct sigqueue *q) { }
>  static inline void posixtimer_sigqueue_putref(struct sigqueue *q) { }
> --- a/kernel/signal.c
> +++ b/kernel/signal.c
> @@ -2092,7 +2092,7 @@ static inline void posixtimer_sig_ignore
>  	 * from a non-periodic timer, then just drop the reference
>  	 * count. Otherwise queue it on the ignored list.
>  	 */
> -	if (tmr->it_signal && tmr->it_sig_periodic)
> +	if (posixtimer_valid(tmr) && tmr->it_sig_periodic)
>  		hlist_add_head(&tmr->ignored_list, &tsk->signal->ignored_posix_timers);
>  	else
>  		posixtimer_putref(tmr);
> --- a/kernel/time/posix-timers.c
> +++ b/kernel/time/posix-timers.c
> @@ -279,7 +279,7 @@ static bool __posixtimer_deliver_signal(
>  	 * since the signal was queued. In either case, don't rearm and
>  	 * drop the signal.
>  	 */
> -	if (timr->it_signal_seq != timr->it_sigqueue_seq || WARN_ON_ONCE(!timr->it_signal))
> +	if (timr->it_signal_seq != timr->it_sigqueue_seq || !posixtimer_valid(timr))

Hmm, should it still warn here? ie: WARN_ON_ONCE(!posixtimer_valid(timr)) ?

Thanks.