linux-kernel - Re: [PATCH 8/8] staging: lustre: put constant on the right of binary operator

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Message-ID: <alpine.DEB.2.02.1508301907310.2062@localhost6.localdomain6>
Date:	Sun, 30 Aug 2015 19:12:09 +0200 (CEST)
From:	Julia Lawall <julia.lawall@...6.fr>
To:	Joe Perches <joe@...ches.com>
cc:	Oleg Drokin <oleg.drokin@...el.com>,
	kernel-janitors@...r.kernel.org,
	Andreas Dilger <andreas.dilger@...el.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	HPDD-discuss@...1.01.org, devel@...verdev.osuosl.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 8/8] staging: lustre: put constant on the right of binary
 operator



On Sat, 29 Aug 2015, Joe Perches wrote:

> On Sat, 2015-08-29 at 19:30 +0200, Julia Lawall wrote:
> > Move constants to the right of binary operators.
> []
> > diff --git a/drivers/staging/lustre/lustre/ptlrpc/client.c b/drivers/staging/lustre/lustre/ptlrpc/client.c
> []
> > @@ -2954,7 +2954,7 @@ void ptlrpc_init_xid(void)
> >  	}
> >  
> >  	/* Always need to be aligned to a power-of-two for multi-bulk BRW */
> > -	CLASSERT((PTLRPC_BULK_OPS_COUNT & (PTLRPC_BULK_OPS_COUNT - 1)) == 0);
> > +	CLASSERT(((PTLRPC_BULK_OPS_COUNT - 1) & PTLRPC_BULK_OPS_COUNT) == 0);
> 
> This one would probably be better as
> 
> 	CLASSERT(is_power_of_2(PTLRPC_BULK_OPS_COUNT));

Actually not.  CLASSERT requires that the expression is considered to be a 
constant by the compiler, such that there will be a compiler error, and 
the result of is_power_of_2 is not constant enough.

julia
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