[PATCH v1] lpfc 8.3.37: Remove redundant NULL check before kfree

[PATCH v1] lpfc 8.3.37: Remove redundant NULL check before kfree

[syamsidhardh]

From: Syam Sidhardhan <s.syam@samsung.com>

kfree on NULL pointer is a no-op.

Signed-off-by: Syam Sidhardhan <s.syam@samsung.com>
---
v1-> Corrected the from address.

 drivers/scsi/lpfc/lpfc_bsg.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/scsi/lpfc/lpfc_bsg.c b/drivers/scsi/lpfc/lpfc_bsg.c
index 32d5683..2166097 100644
--- a/drivers/scsi/lpfc/lpfc_bsg.c
+++ b/drivers/scsi/lpfc/lpfc_bsg.c
@@ -1129,8 +1129,7 @@ lpfc_bsg_hba_set_event(struct fc_bsg_job *job)
 	return 0; /* call job done later */
 
 job_error:
-	if (dd_data != NULL)
-		kfree(dd_data);
+	kfree(dd_data);
 
 	job->dd_data = NULL;
 	return rc;
-- 
1.7.9.5

Re: [PATCH v1] lpfc 8.3.37: Remove redundant NULL check before kfree

[James Smart]

Syam,

Thank you for the patch - it is valid.

However, I prefer not to merge this.  I would rather force the coder to 
think about the pointer value explicitly rather than depending on the 
convenience/one line optimization.  We've had errors in the past covered 
up by this gracious behavior.  Additionally, we have coders that work on 
linux and vmware, and the semantics of the kfree() routine differ.   For 
now, I'd prefer to stay as is and force good habits.

-- james s


On 3/6/2013 3:12 PM, syamsidhardh@gmail.com wrote:
> From: Syam Sidhardhan <s.syam@samsung.com>
>
> kfree on NULL pointer is a no-op.
>
> Signed-off-by: Syam Sidhardhan <s.syam@samsung.com>
> ---
> v1-> Corrected the from address.
>
>   drivers/scsi/lpfc/lpfc_bsg.c |    3 +--
>   1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/scsi/lpfc/lpfc_bsg.c b/drivers/scsi/lpfc/lpfc_bsg.c
> index 32d5683..2166097 100644
> --- a/drivers/scsi/lpfc/lpfc_bsg.c
> +++ b/drivers/scsi/lpfc/lpfc_bsg.c
> @@ -1129,8 +1129,7 @@ lpfc_bsg_hba_set_event(struct fc_bsg_job *job)
>   	return 0; /* call job done later */
>   
>   job_error:
> -	if (dd_data != NULL)
> -		kfree(dd_data);
> +	kfree(dd_data);
>   
>   	job->dd_data = NULL;
>   	return rc;

RE: [PATCH v1] lpfc 8.3.37: Remove redundant NULL check before kfree

[Elliott, Robert (Server Storage)]

If the other approach is taken, then not all kfree() calls are protected by a NULL check.

One example in lpfc_els.c (from 3.7-rc5):
	if (!pbuflist || !pbuflist->virt)
		goto els_iocb_free_pbuf_exit;
...
els_iocb_free_pbuf_exit:
	if (expectRsp)
		lpfc_mbuf_free(phba, prsp->virt, prsp->phys);
	kfree(pbuflist);




> -----Original Message-----
> From: linux-scsi-owner@vger.kernel.org [mailto:linux-scsi-
> owner@vger.kernel.org] On Behalf Of James Smart
> Sent: Wednesday, 06 March, 2013 3:10 PM
> To: syamsidhardh@gmail.com
> Cc: linux-scsi@vger.kernel.org; JBottomley@parallels.com; Syam Sidhardhan;
> Smart, James
> Subject: Re: [PATCH v1] lpfc 8.3.37: Remove redundant NULL check before
> kfree
> 
> Syam,
> 
> Thank you for the patch - it is valid.
> 
> However, I prefer not to merge this.  I would rather force the coder to
> think about the pointer value explicitly rather than depending on the
> convenience/one line optimization.  We've had errors in the past covered
> up by this gracious behavior.  Additionally, we have coders that work on
> linux and vmware, and the semantics of the kfree() routine differ.   For
> now, I'd prefer to stay as is and force good habits.
> 
> -- james s
> 
> 
> On 3/6/2013 3:12 PM, syamsidhardh@gmail.com wrote:
> > From: Syam Sidhardhan <s.syam@samsung.com>
> >
> > kfree on NULL pointer is a no-op.
> >
> > Signed-off-by: Syam Sidhardhan <s.syam@samsung.com>
> > ---
> > v1-> Corrected the from address.
> >
> >   drivers/scsi/lpfc/lpfc_bsg.c |    3 +--
> >   1 file changed, 1 insertion(+), 2 deletions(-)
> >
> > diff --git a/drivers/scsi/lpfc/lpfc_bsg.c b/drivers/scsi/lpfc/lpfc_bsg.c
> > index 32d5683..2166097 100644
> > --- a/drivers/scsi/lpfc/lpfc_bsg.c
> > +++ b/drivers/scsi/lpfc/lpfc_bsg.c
> > @@ -1129,8 +1129,7 @@ lpfc_bsg_hba_set_event(struct fc_bsg_job *job)
> >   	return 0; /* call job done later */
> >
> >   job_error:
> > -	if (dd_data != NULL)
> > -		kfree(dd_data);
> > +	kfree(dd_data);
> >
> >   	job->dd_data = NULL;
> >   	return rc;
> 
> --
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Re: [PATCH v1] lpfc 8.3.37: Remove redundant NULL check before kfree

[James Smart]

I don't disagree.    My intent would be it is all one way - with my 
leaning toward being explicit.  Unfortunately, it's a low priority task.

-- james s


On 3/6/2013 6:32 PM, Elliott, Robert (Server Storage) wrote:
> If the other approach is taken, then not all kfree() calls are protected by a NULL check.
>
> One example in lpfc_els.c (from 3.7-rc5):
> 	if (!pbuflist || !pbuflist->virt)
> 		goto els_iocb_free_pbuf_exit;
> ...
> els_iocb_free_pbuf_exit:
> 	if (expectRsp)
> 		lpfc_mbuf_free(phba, prsp->virt, prsp->phys);
> 	kfree(pbuflist);
>
>
>
>
>> -----Original Message-----
>> From: linux-scsi-owner@vger.kernel.org [mailto:linux-scsi-
>> owner@vger.kernel.org] On Behalf Of James Smart
>> Sent: Wednesday, 06 March, 2013 3:10 PM
>> To: syamsidhardh@gmail.com
>> Cc: linux-scsi@vger.kernel.org; JBottomley@parallels.com; Syam Sidhardhan;
>> Smart, James
>> Subject: Re: [PATCH v1] lpfc 8.3.37: Remove redundant NULL check before
>> kfree
>>
>> Syam,
>>
>> Thank you for the patch - it is valid.
>>
>> However, I prefer not to merge this.  I would rather force the coder to
>> think about the pointer value explicitly rather than depending on the
>> convenience/one line optimization.  We've had errors in the past covered
>> up by this gracious behavior.  Additionally, we have coders that work on
>> linux and vmware, and the semantics of the kfree() routine differ.   For
>> now, I'd prefer to stay as is and force good habits.
>>
>> -- james s
>>
>>
>> On 3/6/2013 3:12 PM, syamsidhardh@gmail.com wrote:
>>> From: Syam Sidhardhan <s.syam@samsung.com>
>>>
>>> kfree on NULL pointer is a no-op.
>>>
>>> Signed-off-by: Syam Sidhardhan <s.syam@samsung.com>
>>> ---
>>> v1-> Corrected the from address.
>>>
>>>    drivers/scsi/lpfc/lpfc_bsg.c |    3 +--
>>>    1 file changed, 1 insertion(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/scsi/lpfc/lpfc_bsg.c b/drivers/scsi/lpfc/lpfc_bsg.c
>>> index 32d5683..2166097 100644
>>> --- a/drivers/scsi/lpfc/lpfc_bsg.c
>>> +++ b/drivers/scsi/lpfc/lpfc_bsg.c
>>> @@ -1129,8 +1129,7 @@ lpfc_bsg_hba_set_event(struct fc_bsg_job *job)
>>>    	return 0; /* call job done later */
>>>
>>>    job_error:
>>> -	if (dd_data != NULL)
>>> -		kfree(dd_data);
>>> +	kfree(dd_data);
>>>
>>>    	job->dd_data = NULL;
>>>    	return rc;
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
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