linux-kernel - Re: [RFC PATCH 1/1] cleanup: use bool as return type for rwsem_is

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Date:	Fri, 06 Jun 2014 19:39:30 -0700
From:	Joe Perches <joe@...ches.com>
To:	Pranith Kumar <bobby.prani@...il.com>
Cc:	Dave Chinner <david@...morbit.com>,
	Pranith Kumar <pranith@...ech.edu>, peterz@...radead.org,
	linux-kernel@...r.kernel.org, tim.c.chen@...ux.intel.com,
	davidlohr@...com, mingo@...hat.com, xfs@....sgi.com
Subject: Re: [RFC PATCH 1/1] cleanup: use bool as return type for
 rwsem_is_locked

On Fri, 2014-06-06 at 21:41 -0400, Pranith Kumar wrote:
> On 06/06/2014 08:59 PM, Pranith Kumar wrote:
> > On 06/06/2014 08:18 PM, Dave Chinner wrote:
> >> 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.
> > Agreed, please find patch below:
> Simplify the "!!" condition. This is much simpler. :)
[]
> diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c

> @@ -285,25 +285,25 @@ xfs_ilock_demote(
>  }
>  
>  #if defined(DEBUG) || defined(XFS_WARN)
> -int
> +bool
>  xfs_isilocked(
>  	xfs_inode_t		*ip,
>  	uint			lock_flags)
>  {
>  	if (lock_flags & (XFS_ILOCK_EXCL|XFS_ILOCK_SHARED)) {
>  		if (!(lock_flags & XFS_ILOCK_SHARED))
> -			return !!ip->i_lock.mr_writer;
> +			return (ip->i_lock.mr_writer != 0);

simpler still would be just removing the !! completely.
I presume in no case would it make an actual difference
in emitted code.

ie:
			return ip->i_lock.mr_writer;


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