linux-kernel - Re: [PATCH 01/16] move copyout of timespec into do_cpu

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Message-ID: <alpine.DEB.2.20.1706130055070.2152@nanos>
Date:   Tue, 13 Jun 2017 01:08:02 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Al Viro <viro@...IV.linux.org.uk>
cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH 01/16] move copyout of timespec into do_cpu_nanosleep()

On Wed, 7 Jun 2017, Al Viro wrote:
> @@ -1242,12 +1243,14 @@ static int do_cpu_nanosleep(const clockid_t which_clock, int flags,
>  
>  		error = -ERESTART_RESTARTBLOCK;
> +		/*
> +		 * Report back to the user the time still remaining.
> +		 */
> +		rmtp = restart->nanosleep.rmtp;
> +		if (rmtp) {
> +			struct timespec ts;
> +			ts = timespec64_to_timespec(it.it_value);
> +			if (copy_to_user(rmtp, &ts, sizeof(*rmtp)))
> +				return -EFAULT;
> +		}
> +		restart->nanosleep.expires = timespec64_to_ns(rqtp);

Hmm, this looks wrong. But that was wrong before this patch already.

The restart code needs the absolute expiry time of the timer, but in case
of flags != ABSTIME rqtp contains the relative expiry time.

So that want's to be fixed first. Need to figure out what's the least ugly
way to do that. I'll have a look tomorrow.

Thanks,

	tglx