linux-kernel - Re: [PATCH 2/7] sched: change wake_up_bit() and related function to expect unsigned long *

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Message-ID: <20240916181817.GF4723@noisy.programming.kicks-ass.net>
Date: Mon, 16 Sep 2024 20:18:17 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: NeilBrown <neilb@...e.de>
Cc: Ingo Molnar <mingo@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Jens Axboe <axboe@...nel.dk>, linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org, linux-block@...r.kernel.org
Subject: Re: [PATCH 2/7] sched: change wake_up_bit() and related function to
 expect unsigned long *

On Mon, Sep 16, 2024 at 09:48:11PM +1000, NeilBrown wrote:
> On Mon, 16 Sep 2024, Peter Zijlstra wrote:
> > On Mon, Aug 26, 2024 at 04:30:59PM +1000, NeilBrown wrote:
> > > wake_up_bit() currently allows a "void *".  While this isn't strictly a
> > > problem as the address is never dereferenced, it is inconsistent with
> > > the corresponding wait_var_event() which requires "unsigned long *" and
> > > does dereference the pointer.
> > 
> > I'm having trouble parsing this. The way I read it, you're contradicting
> > yourself. Where does wait_var_event() require 'unsigned long *' ?
> 
> Sorry, that is meant so as "the corresponding wait_on_bit()".
> 
> 
> > 
> > > And code that needs to wait for a change in something other than an
> > > unsigned long would be better served by wake_up_var().
> > 
> > This, afaict the whole var thing is size invariant. It only cares about
> > the address.
> > 
> 
> Again - wake_up_bit().  Sorry - bits are vars were swimming around my
> brain and I didn't proof-read properly.
> 
> This patch is all "bit", no "var".

OK :-)

Anyway, other than that the patches look fine, but given we're somewhat
in the middle of the merge window and all traveling to get into Vienna
and have a few beers, I would much prefer merging these patches after
-rc1, that okay?