linux-kernel - Re: [PATCH] pstore: Revert pmsg

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Message-ID: <20230304032315.GC2176990@google.com>
Date:   Sat, 4 Mar 2023 03:23:15 +0000
From:   Joel Fernandes <joel@...lfernandes.org>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     John Stultz <jstultz@...gle.com>,
        LKML <linux-kernel@...r.kernel.org>, Wei Wang <wvw@...gle.com>,
        Midas Chien <midaschieh@...gle.com>,
        Kees Cook <keescook@...omium.org>,
        Anton Vorontsov <anton@...msg.org>,
        "Guilherme G. Piccoli" <gpiccoli@...lia.com>,
        Tony Luck <tony.luck@...el.com>, kernel-team@...roid.com,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: Re: [PATCH] pstore: Revert pmsg_lock back to a normal mutex

On Sat, Mar 04, 2023 at 03:01:30AM +0000, Joel Fernandes wrote:
[...]
> > > > > Either way, I think a comment should go on top of the "if (top_waiter !=
> > > > > waiter)" check IMO.  
> > > >
> > > > What type of comment?  
> > > 
> > > Comment explaining why "if (top_waiter != waiter)" is essential :-).
> > 
> 
> Maybe "/* Only the top waiter needs to spin. If we are no longer the
> top-waiter, no point in spinning, as we do not get the lock next anyway. */"
> 
> ?

And it could be added to that comment that, we want to continue spinning as
long as the top-waiter is still on the CPU (even if we are no longer the
top-waiter).

thanks,

 - Joel