linux-kernel - Re: [RFC PATCH] fs: elide the smp_rmb fence in fd

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Message-ID: <CAGudoHEXcYtwijh9zAkjTfZsoO5q=Y3mXk4+m7PJZfOfKZXb4A@mail.gmail.com>
Date: Thu, 5 Dec 2024 16:06:56 +0100
From: Mateusz Guzik <mjguzik@...il.com>
To: Christian Brauner <brauner@...nel.org>
Cc: paulmck@...nel.org, viro@...iv.linux.org.uk, jack@...e.cz, 
	linux-fsdevel@...r.kernel.org, torvalds@...ux-foundation.org, 
	edumazet@...gle.com, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH] fs: elide the smp_rmb fence in fd_install()

On Thu, Dec 5, 2024 at 3:58 PM Christian Brauner <brauner@...nel.org> wrote:
>
> On Thu, Dec 05, 2024 at 01:03:32PM +0100, Mateusz Guzik wrote:
> > +     BUG_ON(files->resize_in_progress);
>
> I think this BUG_ON() here is a bit unnecessary.
>

I'm an assert-friendly guy, but I'm not going to argue about this one.

> > +     files->resize_in_progress = true;
>
> Minor: Why move that into expand_fdtable()? Having
> files->resize_in_progress in here doesn't add much more clarity than
> just having it set around expand_fdtable() in the caller.
>
> Leaving it there also makes the patch smaller and clearer to follow as
> you neither need the additional err nor the goto.

The is indeed not the best looking goto in the world, but per the
commit message I moved the flag in so that it can be easier referred
to when describing synchronisation against fd_install.

-- 
Mateusz Guzik <mjguzik gmail.com>