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References: <20240325140943.815051-1-ubizjak@gmail.com> <171284242025.10875.1534973785149780371.tip-bot2@tip-bot2>
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From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Thu, 11 Apr 2024 09:31:26 -0700
Message-ID: <CAHk-=wgaxi4Sau27C5yo3vty67DHz-f4L6SSOvmx1K2fQU2B_g@mail.gmail.com>
Subject: Re: [tip: locking/core] locking/pvqspinlock: Use try_cmpxchg_acquire()
 in trylock_clear_pending()
To: linux-kernel@vger.kernel.org
Cc: linux-tip-commits@vger.kernel.org, Uros Bizjak <ubizjak@gmail.com>, 
	Ingo Molnar <mingo@kernel.org>, Waiman Long <longman@redhat.com>, x86@kernel.org
Content-Type: text/plain; charset="UTF-8"

On Thu, 11 Apr 2024 at 06:33, tip-bot2 for Uros Bizjak
<tip-bot2@linutronix.de> wrote:
>
> Use try_cmpxchg_acquire(*ptr, &old, new) instead of
> cmpxchg_relaxed(*ptr, old, new) == old in trylock_clear_pending().

The above commit message is horribly confusing and wrong.

I was going "that's not right", because it says "use acquire instead
of relaxed" memory ordering, and then goes on to say "No functional
change intended".

But it turns out the *code* was always acquire, and it's only the
commit message that is wrong, presumably due to a bit too much
cut-and-paste.

But please fix the commit message, and use the right memory ordering
in the explanations too.

            Linus