[bug report] drm: remove usage of drm_pci_alloc/free

[Dan Carpenter]

Hello Joseph Kogut,

The patch 70556e24e18e: "drm: remove usage of drm_pci_alloc/free"
from Apr 22, 2021, leads to the following static checker warning:

    drivers/gpu/drm/drm_bufs.c:1090 drm_legacy_addbufs_pci()
    warn: inconsistent returns '&dev->struct_mutex'.
      Locked on  : 988
      Unlocked on: 938,944,951,959,973,1005,1042,1060,1090

drivers/gpu/drm/drm_bufs.c
   965          temp_pagelist = kmalloc_array(dma->page_count + (count << page_order),
   966                                        sizeof(*dma->pagelist),
   967                                        GFP_KERNEL);
   968          if (!temp_pagelist) {
   969                  kfree(entry->buflist);
   970                  kfree(entry->seglist);
   971                  mutex_unlock(&dev->struct_mutex);
   972                  atomic_dec(&dev->buf_alloc);
   973                  return -ENOMEM;

There is a bunch of clean up happenning on the existing returns.

   974          }
   975          memcpy(temp_pagelist,
   976                 dma->pagelist, dma->page_count * sizeof(*dma->pagelist));
   977          DRM_DEBUG("pagelist: %d entries\n",
   978                    dma->page_count + (count << page_order));
   979  
   980          entry->buf_size = size;
   981          entry->page_order = page_order;
   982          byte_count = 0;
   983          page_count = 0;
   984  
   985          while (entry->buf_count < count) {
   986                  dmah = kmalloc(sizeof(drm_dma_handle_t), GFP_KERNEL);
   987                  if (!dmah)
   988                          return -ENOMEM;

This new return has no clean up.  We a mutex_unlock(&dev->struct_mutex).

   989  
   990                  dmah->size = total;
   991                  dmah->vaddr = dma_alloc_coherent(dev->dev,
   992                                                   dmah->size,
   993                                                   &dmah->busaddr,
   994                                                   GFP_KERNEL);
   995                  if (!dmah->vaddr) {
   996                          kfree(dmah);
   997  
   998                          /* Set count correctly so we free the proper amount. */
   999                          entry->buf_count = count;
  1000                          entry->seg_count = count;
  1001                          drm_cleanup_buf_error(dev, entry);
  1002                          kfree(temp_pagelist);
  1003                          mutex_unlock(&dev->struct_mutex);
  1004                          atomic_dec(&dev->buf_alloc);
  1005                          return -ENOMEM;
  1006                  }
  1007                  entry->seglist[entry->seg_count++] = dmah;
  1008                  for (i = 0; i < (1 << page_order); i++) {
  1009                          DRM_DEBUG("page %d @ 0x%08lx\n",

regards,
dan carpenter