linux-kernel - Re: [PATCH 1/2] torture: use for_each_present() loop in torture_online

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Message-ID: <yt9dtu31k0r9.fsf@linux.ibm.com>
Date:   Mon, 14 Nov 2022 16:35:06 +0100
From:   Sven Schnelle <svens@...ux.ibm.com>
To:     "Paul E. McKenney" <paulmck@...nel.org>
Cc:     Davidlohr Bueso <dave@...olabs.net>,
        Josh Triplett <josh@...htriplett.org>,
        linux-kernel@...r.kernel.org, rcu@...r.kernel.org
Subject: Re: [PATCH 1/2] torture: use for_each_present() loop in
 torture_online_all()

"Paul E. McKenney" <paulmck@...nel.org> writes:

> On Fri, Nov 11, 2022 at 01:51:24PM +0100, Sven Schnelle wrote:
>> A CPU listed in the possible mask doesn't have to be present, in
>> which case it would crash the kernel in torture_online_all().
>> To prevent this use a for_each_present() loop.
>> 
>> Signed-off-by: Sven Schnelle <svens@...ux.ibm.com>
>
> Looks good to me!  Any reason for no mailing list on CC?

No, my fault. I setup get_maintainer.pl to be called from git
send-email, but looks like i did it wrong :-)

> Ah, and any synchronization required in case it is possible for a CPU
> to leave the cpu_present_mask?  Or can they only be added?

Hmm... I think the main question is, whether it is ok for a cpu to be
removed from the system when rcutorture is running? In both cases it
would disappear from the cpu online mask, so i don't think the patch
would change the behaviour. But i can check and send additional patches
if there are other places that needs adjustment.

Regards
Sven