Re: [PATCH] zfcp: Test kmalloc failure in scsi_get_vpd_page()

[Boaz Harrosh <bharrosh@panasas.com>]

On 08/28/2009 02:45 AM, James Bottomley wrote:
> On Mon, 2009-08-24 at 18:21 +0200, Roel Kluin wrote:
>> kmalloc() may fail, so test whether it succeeded.
>>
>> Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
>> ---
>> diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
>> index 2de5f3a..34fdde0 100644
>> --- a/drivers/scsi/scsi.c
>> +++ b/drivers/scsi/scsi.c
>> @@ -1056,6 +1056,9 @@ unsigned char *scsi_get_vpd_page(struct scsi_device *sdev, u8 page)
>>  
>>  	kfree(buf);
>>  	buf = kmalloc(len + 4, GFP_KERNEL);
>> +	if (!buf)
>> +		return NULL;
>> +
> 
> Firstly, this won't actually apply ... you should be developing against
> either the SCSI trees or linux-next to get the latest versions in git.
> 
> Secondly it's not really right for the most common use cases, which
> don't usually want the whole vpd buffer anyway.  I don't really see a
> simple way of fixing it without altering the interface, though.
> 

"most common use cases" do not have pages bigger then 255. Can you think
of any? For these few places that anticipate pages bigger then 255 I don't
see much choice, we just freed 255 bytes and tried a new size, say 317, which
failed with GFP_KERNEL, In such a busy system, better fail with NULL then BUG,
No? In any way caller must check for NULL because of the first allocation.

> James
> 

Boaz