linux-kernel - Re: [PATCH v7 02/10] staging: fsl-mc: fix macros with possible side effects

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Date:   Wed, 14 Jun 2017 12:27:17 +0000
From:   Laurentiu Tudor <laurentiu.tudor@....com>
To:     Greg KH <gregkh@...uxfoundation.org>
CC:     "stuyoder@...il.com" <stuyoder@...il.com>,
        "devel@...verdev.osuosl.org" <devel@...verdev.osuosl.org>,
        "arnd@...db.de" <arnd@...db.de>,
        "marc.zyngier@....com" <marc.zyngier@....com>,
        Roy Pledge <roy.pledge@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "agraf@...e.de" <agraf@...e.de>,
        "Catalin Horghidan" <catalin.horghidan@....com>,
        Ioana Ciornei <ioana.ciornei@....com>,
        Leo Li <leoyang.li@....com>,
        Bharat Bhushan <bharat.bhushan@....com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v7 02/10] staging: fsl-mc: fix macros with possible side
 effects



On 06/13/2017 01:12 PM, Greg KH wrote:
> On Thu, Jun 08, 2017 at 05:28:47PM +0300, laurentiu.tudor@....com wrote:
>> From: Laurentiu Tudor <laurentiu.tudor@....com>
>>
>> Several macros were triggering this checkpatch.pl warning:
>>    "Macro argument reuse '$arg' - possible side-effects?"
>> Fix the warning by avoiding multiple macro argument use.
>>
>> Signed-off-by: Laurentiu Tudor <laurentiu.tudor@....com>
>> ---
>>
>> Notes:
>>      -v7
>>        -no changes
>>
>>   drivers/staging/fsl-mc/bus/dprc-driver.c      | 10 +++++++---
>>   drivers/staging/fsl-mc/bus/fsl-mc-allocator.c | 11 +++++++----
>>   2 files changed, 14 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/staging/fsl-mc/bus/dprc-driver.c b/drivers/staging/fsl-mc/bus/dprc-driver.c
>> index d723c69..39c9a3b 100644
>> --- a/drivers/staging/fsl-mc/bus/dprc-driver.c
>> +++ b/drivers/staging/fsl-mc/bus/dprc-driver.c
>> @@ -21,9 +21,13 @@
>>
>>   #define FSL_MC_DPRC_DRIVER_NAME    "fsl_mc_dprc"
>>
>> -#define FSL_MC_DEVICE_MATCH(_mc_dev, _obj_desc) \
>> -	(strcmp((_mc_dev)->obj_desc.type, (_obj_desc)->type) == 0 && \
>> -	 (_mc_dev)->obj_desc.id == (_obj_desc)->id)
>> +#define FSL_MC_DEVICE_MATCH(_mc_dev, _obj_desc)				\
>> +({									\
>> +	struct fsl_mc_device *__mc_dev = _mc_dev;			\
>> +	struct dprc_obj_desc *__obj_desc = _obj_desc;			\
>> +	(strcmp(__mc_dev->obj_desc.type, __obj_desc->type) == 0 &&	\
>> +	__mc_dev->obj_desc.id == __obj_desc->id);			\
>> +})
>
> Ick, no.  Just make this a real function please.
>
>>
>>   struct dprc_child_objs {
>>   	int child_count;
>> diff --git a/drivers/staging/fsl-mc/bus/fsl-mc-allocator.c b/drivers/staging/fsl-mc/bus/fsl-mc-allocator.c
>> index ce07096..d3def40 100644
>> --- a/drivers/staging/fsl-mc/bus/fsl-mc-allocator.c
>> +++ b/drivers/staging/fsl-mc/bus/fsl-mc-allocator.c
>> @@ -17,10 +17,13 @@
>>   #include "dpcon-cmd.h"
>>   #include "fsl-mc-private.h"
>>
>> -#define FSL_MC_IS_ALLOCATABLE(_obj_type) \
>> -	(strcmp(_obj_type, "dpbp") == 0 || \
>> -	 strcmp(_obj_type, "dpmcp") == 0 || \
>> -	 strcmp(_obj_type, "dpcon") == 0)
>> +#define FSL_MC_IS_ALLOCATABLE(_obj_type)	\
>> +({						\
>> +	const char *__obj_type = _obj_type;	\
>> +	(strcmp(__obj_type, "dpbp") == 0 ||	\
>> +	 strcmp(__obj_type, "dpmcp") == 0 ||	\
>> +	 strcmp(__obj_type, "dpcon") == 0);	\
>> +})
>
> Same here.  Don't put real logic in a #define, it never makes sense to
> do it and only makes things much harder to debug.
>

Ok, will do. Lets drop this patch and i'll send another one changing all 
these to functions.

---
Thanks & Best Regards, Laurentiu