Re: [libata:upstream 7/11] drivers/ata/libata-zpodd.c:83 zpodd_wake_dev() warn: variable dereferenced before check 'ata_dev' (see line 80)

[Dan Carpenter <dan.carpenter@oracle.com>]

On Tue, Jan 22, 2013 at 04:32:06PM +0800, Aaron Lu wrote:
> Hi Dan,
> 
> Thanks for the remind.
> 
> On 01/22/2013 02:25 PM, Dan Carpenter wrote:
> > Hi Aaron,
> > 
> > FYI, there are new smatch warnings show up in
> > 
> > tree:   git://git.kernel.org/pub/scm/linux/kernel/git/jgarzik/libata-dev.git upstream
> > head:   7e15e9be37eb834aaaca69030064ac97eaf5df2f
> > commit: f064a20dded807448669426c9bfb7d03aba5659c [7/11] libata: move acpi notification code to zpodd
> > 
> > New smatch warnings:
> > drivers/ata/libata-zpodd.c:83 zpodd_wake_dev() warn: variable dereferenced before check 'ata_dev' (see line 80)
> 
> The ata_dev variable shouldn't ever be NULL here.
> 
> > 
> > git remote add libata git://git.kernel.org/pub/scm/linux/kernel/git/jgarzik/libata-dev.git
> > git remote update libata
> > git checkout f064a20dded807448669426c9bfb7d03aba5659c
> > vim +/ata_dev +83 drivers/ata/libata-zpodd.c
> > 
> > afe75951 Aaron Lu 2013-01-15  74  	return acpi_device_can_poweroff(acpi_dev);
> > afe75951 Aaron Lu 2013-01-15  75  }
> > afe75951 Aaron Lu 2013-01-15  76  
> > f064a20d Aaron Lu 2013-01-15  77  static void zpodd_wake_dev(acpi_handle handle, u32 event, void *context)
> > f064a20d Aaron Lu 2013-01-15  78  {
> > f064a20d Aaron Lu 2013-01-15  79  	struct ata_device *ata_dev = context;
> > f064a20d Aaron Lu 2013-01-15 @80  	struct zpodd *zpodd = ata_dev->zpodd;
> > f064a20d Aaron Lu 2013-01-15  81  	struct device *dev = &ata_dev->sdev->sdev_gendev;
> > f064a20d Aaron Lu 2013-01-15  82  
> > f064a20d Aaron Lu 2013-01-15 @83  	if (event == ACPI_NOTIFY_DEVICE_WAKE && ata_dev &&
> 
> If I remove the check for ata_dev here, will the smatch warning go away?
> Or should I add a check above? I suppose we need to do something to the
> warning, so that it won't pop up in the future, so please feel free to
> suggest, thanks!

Removing the check would silence the warning.

regards,
dan carpenter