linux-kernel - Re: [PATCH] locking/rwlocks: do not starve writers

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Message-ID: <CAHk-=wiEZmzBUFkZkBrJv3JSJkQ+qxaMZU_Sx1WTpMHs2SOAiQ@mail.gmail.com>
Date:   Fri, 17 Jun 2022 14:48:08 -0500
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Eric Dumazet <edumazet@...gle.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Waiman Long <longman@...hat.com>,
        Shakeel Butt <shakeelb@...gle.com>,
        Eric Dumazet <eric.dumazet@...il.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...hat.com>,
        Boqun Feng <boqun.feng@...il.com>,
        Will Deacon <will@...nel.org>, Roman Penyaev <rpenyaev@...e.de>
Subject: Re: [PATCH] locking/rwlocks: do not starve writers

On Fri, Jun 17, 2022 at 2:39 PM Eric Dumazet <edumazet@...gle.com> wrote:
>
> I am converting RAW sockets to RCU.

RCU is usually absolutely the best approach. Use regular spinlocks for
writers, and RCU for readers.

I'd love to see the tasklist_lock be converted to RCU too.  But that
locks predates RCU (and probably 99% of all kernel code), and it's
messy, so nobody sane has ever willingly tried to do that afaik.

               Linus