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
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