Linux Virtualization - Feb 2013 - xen/acpi: ACPI memory hotplug

Hello Liu Jinsong,

This is a semi-automatic email about new static checker warnings.

The patch 259f201cb7ea: "xen/acpi: ACPI memory hotplug" from Jan 24, 
2013, leads to the following Smatch complaint:

drivers/xen/xen-acpi-memhotplug.c:198 acpi_memory_get_device()
	 error: we previously assumed 'device' could be null (see line 171)

drivers/xen/xen-acpi-memhotplug.c
   170	
   171		if (!acpi_bus_get_device(handle, &device) && device)
                                                             ^^^^^^
New check.

Btw, checking device is unnecessary.

		if (acpi_bus_get_device(handle, &device) == 0)
			goto end;

A successful "Get Device" means that "device" is non-NULL;
that's built
into the name.  Anyway, if acpi_bus_get_device() fails either something
else will fail or we will Oops in the call to acpi_driver_data().

   172			goto end;
   173	
   174		status = acpi_get_parent(handle, &phandle);
   175		if (ACPI_FAILURE(status)) {
   176			pr_warn(PREFIX "Cannot find acpi parent\n");
   177			return -EINVAL;
   178		}
   179	
   180		/* Get the parent device */
   181		result = acpi_bus_get_device(phandle, &pdevice);
   182		if (result) {
   183			pr_warn(PREFIX "Cannot get acpi bus device\n");
   184			return -EINVAL;
   185		}
   186	
   187		/*
   188		 * Now add the notified device.  This creates the acpi_device
   189		 * and invokes .add function
   190		 */
   191		result = acpi_bus_scan(handle);
   192		if (result) {
   193			pr_warn(PREFIX "Cannot add acpi bus\n");
   194			return -EINVAL;
   195		}
   196	
   197	end:
   198		*mem_device = acpi_driver_data(device);
                                               ^^^^^^
Dereference.

   199		if (!(*mem_device)) {
   200			pr_err(PREFIX "Driver data not found\n");

regards,
dan carpenter

Dan Carpenter wrote:
> Hello Liu Jinsong,
> 
> This is a semi-automatic email about new static checker warnings.
> 
> The patch 259f201cb7ea: "xen/acpi: ACPI memory hotplug" from Jan
24,
> 2013, leads to the following Smatch complaint:
> 
> drivers/xen/xen-acpi-memhotplug.c:198 acpi_memory_get_device()
> 	 error: we previously assumed 'device' could be null (see line
171)
> 
> drivers/xen/xen-acpi-memhotplug.c
>    170
>    171		if (!acpi_bus_get_device(handle, &device) && device)
>                                                              ^^^^^^
> New check.
> 
> Btw, checking device is unnecessary.
> 
> 		if (acpi_bus_get_device(handle, &device) == 0)
> 			goto end;
> 
> A successful "Get Device" means that "device" is
non-NULL; that's
> built into the name.  Anyway, if acpi_bus_get_device() fails either
> something else will fail or we will Oops in the call to
> acpi_driver_data(). 
> 
>    172			goto end;
>    173
>    174		status = acpi_get_parent(handle, &phandle);
>    175		if (ACPI_FAILURE(status)) {
>    176			pr_warn(PREFIX "Cannot find acpi parent\n");
>    177			return -EINVAL;
>    178		}
>    179
>    180		/* Get the parent device */
>    181		result = acpi_bus_get_device(phandle, &pdevice);
>    182		if (result) {
>    183			pr_warn(PREFIX "Cannot get acpi bus device\n");
>    184			return -EINVAL;
>    185		}
>    186
>    187		/*
>    188		 * Now add the notified device.  This creates the acpi_device
>    189		 * and invokes .add function
>    190		 */
>    191		result = acpi_bus_scan(handle);
>    192		if (result) {
>    193			pr_warn(PREFIX "Cannot add acpi bus\n");
>    194			return -EINVAL;
>    195		}
>    196
>    197	end:
>    198		*mem_device = acpi_driver_data(device);
>                                                ^^^^^^
> Dereference.
> 
>    199		if (!(*mem_device)) {
>    200			pr_err(PREFIX "Driver data not found\n");
> 
> regards,
> dan carpenter
Thanks Dan, updated, will send out minutes later.

Regards,
Jinsong