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Re: [RFC PATCH 1/1] cleanup: use bool as return type for rwsem_is_locked

To: Pranith Kumar <pranith@xxxxxxxxxx>
Subject: Re: [RFC PATCH 1/1] cleanup: use bool as return type for rwsem_is_locked
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Sat, 7 Jun 2014 10:18:19 +1000
Cc: peterz@xxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, tim.c.chen@xxxxxxxxxxxxxxx, davidlohr@xxxxxx, mingo@xxxxxxxxxx, xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <53920446.7060505@xxxxxxxxxx>
References: <5390D7E1.7060606@xxxxxxxxxx> <5391FFFD.1060901@xxxxxxxxxx> <53920446.7060505@xxxxxxxxxx>
User-agent: Mutt/1.5.21 (2010-09-15)
On Fri, Jun 06, 2014 at 02:11:18PM -0400, Pranith Kumar wrote:
> On 06/06/2014 01:53 PM, Pranith Kumar wrote:
> > On Fri, Jun 6, 2014 at 3:35 AM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> >>
> >> Now in general, I don't particularly like such superfluous changes, so
> >> unless you can show that GCC actually generates better code, I'd prefer
> >> to keep things as they are.
> > 
> > Fixed and checked the assembly. It saves us 2 bytes of code, not much. I am 
> > not sure if that is worth it :(
> > 
> > use bool as the return type for rwsem_is_locked() instead of int
> > 
> > Signed-off-by: Pranith Kumar <bobby.prani@xxxxxxxxx>
....

Makes sense to me.

> I observed one other user of rwsem_is_locked() in xfs, change accordingly
> 
> Signed-off-by: Pranith Kumar <bobby.prani@xxxxxxxxx>
> ---
>  fs/xfs/xfs_inode.c |    2 +-
>  fs/xfs/xfs_inode.h |    2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
> index 768087b..9047eda 100644
> --- a/fs/xfs/xfs_inode.c
> +++ b/fs/xfs/xfs_inode.c
> @@ -285,7 +285,7 @@ xfs_ilock_demote(
>  }
>  
>  #if defined(DEBUG) || defined(XFS_WARN)
> -int
> +bool
>  xfs_isilocked(
>       xfs_inode_t             *ip,
>       uint                    lock_flags)

If you are going to change the return type to bool, then you should
also remove the manual "!!" conversions to a boolean return and let
the compiler do it in the most optimal way.

Cheers,

Dave.
-- 
Dave Chinner
david@xxxxxxxxxxxxx

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