linux-kernel - Re: [PATCH 5/5]scsi:hosts.c Fix warning: variable 'rval' set but not used

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Date:	Wed, 16 Jun 2010 11:14:22 -0700
From:	"Justin P. Mattock" <justinmattock@...il.com>
To:	James Bottomley <James.Bottomley@...e.de>
CC:	linux-kernel@...r.kernel.org, linux-wireless@...r.kernel.org,
	linux-pci@...r.kernel.org, linux-scsi@...r.kernel.org
Subject: Re: [PATCH 5/5]scsi:hosts.c Fix warning: variable 'rval' set but
 not used

On 06/16/2010 10:33 AM, James Bottomley wrote:
> On Wed, 2010-06-16 at 09:00 -0700, Justin P. Mattock wrote:
>> On 06/16/2010 08:34 AM, James Bottomley wrote:
>>> On Tue, 2010-06-15 at 22:33 -0700, Justin P. Mattock wrote:
>>>> The below patch fixes a warning message generated by gcc 4.6.0
>>>>     CC      drivers/scsi/hosts.o
>>>> drivers/scsi/hosts.c: In function 'scsi_host_alloc':
>>>> drivers/scsi/hosts.c:328:6: warning: variable 'rval' set but not used
>>>>
>>>>    Signed-off-by: Justin P. Mattock<justinmattock@...il.com>
>>>>
>>>> ---
>>>>    drivers/scsi/hosts.c |    2 --
>>>>    1 files changed, 0 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
>>>> index 6660fa9..00fd6a4 100644
>>>> --- a/drivers/scsi/hosts.c
>>>> +++ b/drivers/scsi/hosts.c
>>>> @@ -325,7 +325,6 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
>>>>    {
>>>>    	struct Scsi_Host *shost;
>>>>    	gfp_t gfp_mask = GFP_KERNEL;
>>>> -	int rval;
>>>>
>>>>    	if (sht->unchecked_isa_dma&&   privsize)
>>>>    		gfp_mask |= __GFP_DMA;
>>>> @@ -420,7 +419,6 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
>>>>    	shost->ehandler = kthread_run(scsi_error_handler, shost,
>>>>    			"scsi_eh_%d", shost->host_no);
>>>>    	if (IS_ERR(shost->ehandler)) {
>>>> -		rval = PTR_ERR(shost->ehandler);
>>>>    		goto fail_kfree;
>>>>    	}
>>>
>>> For future reference, this is less stylistically acceptable C: you've
>>> reduced the if clause to a single statement, so the braces need
>>> removing.
>>>
>>> However, I don't think we should be ignoring the fact that the eh thread
>>> failed to spawn, so I think some type of printed warning (giving the
>>> error code) would be a much more appropriate replacement.
>>>
>>> James
>>>
>>>
>>>
>>
>>
>> o.k. I'll give a try at that.. as a  test I did this(below) seemed to
>> compile clean, but not sure if this is what you're asking for though:
>>
>>
>>   From 8a4d6e793e0f92d180a6f48c53bbf00d2751ad01 Mon Sep 17 00:00:00 2001
>> From: Justin P. Mattock<justinmattock@...il.com>
>> Date: Wed, 16 Jun 2010 08:58:13 -0700
>> Subject: [PATCH] test
>>    Signed-off-by: Justin P. Mattock<justinmattock@...il.com>
>>
>> ---
>>    drivers/scsi/hosts.c |    3 +--
>>    1 files changed, 1 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
>> index 6660fa9..8d98a46 100644
>> --- a/drivers/scsi/hosts.c
>> +++ b/drivers/scsi/hosts.c
>> @@ -325,7 +325,6 @@ struct Scsi_Host *scsi_host_alloc(struct
>> scsi_host_template *sht, int privsize)
>>    {
>>    	struct Scsi_Host *shost;
>>    	gfp_t gfp_mask = GFP_KERNEL;
>> -	int rval;
>>
>>    	if (sht->unchecked_isa_dma&&  privsize)
>>    		gfp_mask |= __GFP_DMA;
>> @@ -420,7 +419,7 @@ struct Scsi_Host *scsi_host_alloc(struct
>> scsi_host_template *sht, int privsize)
>>    	shost->ehandler = kthread_run(scsi_error_handler, shost,
>>    			"scsi_eh_%d", shost->host_no);
>>    	if (IS_ERR(shost->ehandler)) {
>> -		rval = PTR_ERR(shost->ehandler);
>> +		printk(KERN_WARNING "test.....\n")
>
> Erm, well, as I said, error code and the fact that the thread failed to
> start, so more
>
> printk(KERN_WARNING "scsi%d: error handler thread failed to spawn, error
> = %d\n", host->host_no, PTR_ERR(shost->ehandler));
>
> James
>
>
>
>

yeah I figured the printk needed more. I was more concerned with making 
sure this is what you are asking for(which looks like it is).
So I added your printk but ended up getting an undeclared error:

   CC      drivers/scsi/hosts.o
drivers/scsi/hosts.c: In function 'scsi_host_alloc':
drivers/scsi/hosts.c:422:85: error: 'host' undeclared (first use in this 
function)
drivers/scsi/hosts.c:422:85: note: each undeclared identifier is 
reported only once for each function it appears in
make[2]: *** [drivers/scsi/hosts.o] Error 1
make[1]: *** [drivers/scsi] Error 2
make: *** [drivers] Error 2


I do see a
shost->host_no
but using this seems to not satisfy the compiler:

drivers/scsi/hosts.c: In function 'scsi_host_alloc':
drivers/scsi/hosts.c:422:3: warning: format '%d' expects type 'int', but 
argument 3 has type 'long int'

I guess it's safe to say my newbieness is getting my a** kicked with 
code(all part of the learning experience..)

Justin P. Mattock
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