linux-kernel - Re: [PATCH] fs/affs: Replace binary semaphores with mutexes

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Message-ID: <20191030113252.GD3001@suse.cz>
Date:   Wed, 30 Oct 2019 12:32:52 +0100
From:   David Sterba <dsterba@...e.cz>
To:     Davidlohr Bueso <dave@...olabs.net>
Cc:     dsterba@...e.com, linux-kernel@...r.kernel.org,
        Davidlohr Bueso <dbueso@...e.de>
Subject: Re: [PATCH] fs/affs: Replace binary semaphores with mutexes

On Sun, Oct 27, 2019 at 03:01:43PM -0700, Davidlohr Bueso wrote:
> At a slight footprint cost (24 vs 32 bytes), mutexes are more optimal
> than semaphores; it's also a nicer interface for mutual exclusion,
> which is why they are encouraged over binary semaphores, when possible.
> 
> For both i_link_lock and i_ext_lock (and hence i_hash_lock which I
> annotated for the hash lock mapping hackery for lockdep), their semantics
> imply traditional lock ownership; that is, the lock owner is the same for
> both lock/unlock operations and does not run in irq context. Therefore
> it is safe to convert.
> 
> Signed-off-by: Davidlohr Bueso <dbueso@...e.de>

Thanks, I'll add it to affs queue.