From mboxrd@z Thu Jan  1 00:00:00 1970
From: Rolf Eike Beer <eike-kernel@sf-tec.de>
Subject: Re: [PATCH 1/2] Consolidate min_not_zero
Date: Fri, 10 Sep 2010 10:13:51 +0200
Message-ID: <201009101014.00667.eike-kernel@sf-tec.de>
References: <1284095925-12841-1-git-send-email-martin.petersen@oracle.com> <1284095925-12841-2-git-send-email-martin.petersen@oracle.com>
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To: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: jens.axboe@oracle.com, James.Bottomley@hansenpartnership.com, christof.schmitt@de.ibm.com, linux-scsi@vger.kernel.org

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> --- a/include/linux/kernel.h
> +++ b/include/linux/kernel.h
> @@ -636,6 +636,12 @@ static inline void ftrace_dump(enum ftrace_dump_mode
> oops_dump_mode) { } (void) (&_max1 =3D=3D &_max2);		\
>  	_max1 > _max2 ? _max1 : _max2; })
>=20
> +/*
> + * Returns the minimum that is _not_ zero, unless both are zero.
> + */
> +#define min_not_zero(__x, __y) ({		\
> +	__x =3D=3D 0 ? __y : ((__y =3D=3D 0) ? __x : min(__x, __y)); })
> +
>  /**
>   * clamp - return a value clamped to a given range with strict
> typechecking * @val: current value

This will evaluate the value of __x and __y multiple times. Something like=
=20
this should be better (untested):

define min_not_zero(__x, __y) ({		\
	typeof(__x) _minz1 =3D (__x);			\
	typeof(__y) _minz2 =3D (__y);			\
	_minz1 =3D=3D 0 ? _minz2 : ((_minz2 =3D=3D 0) ? _minz1 : min(_minz1, _minz=
2)); })

Eike

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