[bug report] drm/amdkfd: Fix the warning of array-index-out-of-bounds

[Dan Carpenter]

[ Ugh...  My email messed up and I have to Resend all my emails for the
  past two weeks. -dan ]

Hello Ma Jun,

The patch c0cc999f3c32: "drm/amdkfd: Fix the warning of
array-index-out-of-bounds" from Nov 2, 2022, leads to the following
Smatch static checker warning:

	drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_topology.c:2008 kfd_topology_add_device()
	warn: inconsistent returns '&topology_lock'.

drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_topology.c
    1808 int kfd_topology_add_device(struct kfd_dev *gpu)
    1809 {
    1810         uint32_t gpu_id;
    1811         struct kfd_topology_device *dev;
    1812         struct kfd_cu_info cu_info;
    1813         int res = 0;
    1814         struct list_head temp_topology_device_list;
    1815         void *crat_image = NULL;
    1816         size_t image_size = 0;
    1817         int proximity_domain;
    1818         int i;
    1819         const char *asic_name = amdgpu_asic_name[gpu->adev->asic_type];
    1820 
    1821         INIT_LIST_HEAD(&temp_topology_device_list);
    1822 
    1823         gpu_id = kfd_generate_gpu_id(gpu);
    1824         pr_debug("Adding new GPU (ID: 0x%x) to topology\n", gpu_id);
    1825 
    1826         /* Check to see if this gpu device exists in the topology_device_list.
    1827          * If so, assign the gpu to that device,
    1828          * else create a Virtual CRAT for this gpu device and then parse that
    1829          * CRAT to create a new topology device. Once created assign the gpu to
    1830          * that topology device
    1831          */
    1832         down_write(&topology_lock);
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^
Takes the lock.

    1833         dev = kfd_assign_gpu(gpu);
    1834         if (!dev) {
    1835                 proximity_domain = ++topology_crat_proximity_domain;
    1836 
    1837                 res = kfd_create_crat_image_virtual(&crat_image, &image_size,
    1838                                                     COMPUTE_UNIT_GPU, gpu,
    1839                                                     proximity_domain);
    1840                 if (res) {
    1841                         pr_err("Error creating VCRAT for GPU (ID: 0x%x)\n",
    1842                                gpu_id);
    1843                         topology_crat_proximity_domain--;
    1844                         return res;

Does not drop the lock.

    1845                 }
    1846 
    1847                 res = kfd_parse_crat_table(crat_image,
    1848                                            &temp_topology_device_list,
    1849                                            proximity_domain);
    1850                 if (res) {
    1851                         pr_err("Error parsing VCRAT for GPU (ID: 0x%x)\n",
    1852                                gpu_id);
    1853                         topology_crat_proximity_domain--;
    1854                         goto err;

Does not drop the lock.

    1855                 }
    1856 
    1857                 kfd_topology_update_device_list(&temp_topology_device_list,
    1858                         &topology_device_list);
    1859 
    1860                 dev = kfd_assign_gpu(gpu);
    1861                 if (WARN_ON(!dev)) {
    1862                         res = -ENODEV;
    1863                         goto err;

Does not drop the lock.

    1864                 }
    1865 
    1866                 /* Fill the cache affinity information here for the GPUs
    1867                  * using VCRAT
    1868                  */
    1869                 kfd_fill_cache_non_crat_info(dev, gpu);
    1870 
    1871                 /* Update the SYSFS tree, since we added another topology
    1872                  * device
    1873                  */
    1874                 res = kfd_topology_update_sysfs();
    1875                 if (!res)
    1876                         sys_props.generation_count++;
    1877                 else
    1878                         pr_err("Failed to update GPU (ID: 0x%x) to sysfs topology. res=%d\n",
    1879                                                 gpu_id, res);
    1880         }
    1881         up_write(&topology_lock);
                 ^^^^^^^^^^^^^^^^^^^^^^^^^
Drops the lock.  The patch has some other locking changes which are
not explained in the commit message and seem unrelated to the out of
bounds issue.

    1882 
    1883         dev->gpu_id = gpu_id;
    1884         gpu->id = gpu_id;

regards,
dan carpenter