linux-kernel - Re: [PATCH 2/6] kernel: add task

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Message-ID: <20201008132444.GF9995@redhat.com>
Date:   Thu, 8 Oct 2020 15:24:44 +0200
From:   Oleg Nesterov <oleg@...hat.com>
To:     Jens Axboe <axboe@...nel.dk>
Cc:     linux-kernel@...r.kernel.org, io-uring@...r.kernel.org,
        peterz@...radead.org, tglx@...utronix.de
Subject: Re: [PATCH 2/6] kernel: add task_sigpending() helper

On 10/05, Jens Axboe wrote:
>
> @@ -4447,7 +4447,7 @@ SYSCALL_DEFINE0(pause)
>  		__set_current_state(TASK_INTERRUPTIBLE);
>  		schedule();
>  	}
> -	return -ERESTARTNOHAND;
> +	return task_sigpending(current) ? -ERESTARTNOHAND : -ERESTARTSYS;
>  }
>
>  #endif
> @@ -4462,7 +4462,7 @@ static int sigsuspend(sigset_t *set)
>  		schedule();
>  	}
>  	set_restore_sigmask();
> -	return -ERESTARTNOHAND;
> +	return task_sigpending(current) ? -ERESTARTNOHAND : -ERESTARTSYS;
>  }

Both changes are equally wrong. Why do you think sigsuspend() should ever
return -ERESTARTSYS ?

If get_signal() deques a signal, handle_signal() will restart this syscall
if ERESTARTSYS, this is wrong.

Oleg.