linux-kernel - Re: [patch V2 25/50] signal: Confine POSIX

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Message-ID: <87v84dx603.ffs@tglx>
Date: Fri, 19 Apr 2024 07:42:52 +0200
From: Thomas Gleixner <tglx@...utronix.de>
To: Oleg Nesterov <oleg@...hat.com>
Cc: LKML <linux-kernel@...r.kernel.org>, Anna-Maria Behnsen
 <anna-maria@...utronix.de>, 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 V2 25/50] signal: Confine POSIX_TIMERS properly

On Thu, Apr 18 2024 at 17:23, Oleg Nesterov wrote:
> On 04/11, Thomas Gleixner wrote:
>> +static inline void posixtimer_rearm_itimer(struct task_struct *p) { }
>> +static inline void posixtimer_rearm(struct kernel_siginfo *info) { }
>
> Do we really need these 2 nops ? please see below.

>> +		if (unlikely(signr == SIGALRM))
>> +			posixtimer_rearm_itimer(tsk);
>
> ...
>
>> +	if (IS_ENABLED(CONFIG_POSIX_TIMERS)) {
>> +		if (unlikely(resched_timer))
>> +			posixtimer_rearm(info);
>>  	}
>
> This looks a bit inconsistent to me.
>
> Can't we change the callsite of posixtimer_rearm_itimer() to check
> IS_ENABLED(CONFIG_POSIX_TIMERS) too,
>
> 		if (IS_ENABLED(CONFIG_POSIX_TIMERS)) {
> 			if (unlikely(signr == SIGALRM))
> 				posixtimer_rearm_itimer(tsk);
> 		}
> ?
>
> This will make the code more symmetrical, and we can avoid the dumb
> definitions of posixtimer_rearm_itimer/posixtimer_rearm.

Yes, we just need to expose the actual function prototypes
unconditionally. Let me fix that.

Thanks,

        tglx