drivers: pci: hailo: Better lock handling when calling find_vdma()

Due to possible instabilities, reduce the mmap read lock time to only
cover the call to find_vdma().

Signed-off-by: Naushir Patuck <[email protected]>

Author: naushir

drivers/media/pci/hailo/vdma/memory.c

@@ -161,16 +161,18 @@ struct hailo_vdma_buffer *hailo_vdma_buffer_map(struct device *dev,
         dev_err(dev, "memory alloc failed\n");
         ret = -ENOMEM;
         goto cleanup;
+
     }
 
-    mmap_read_lock(current->mm);
     if (HAILO_DMA_DMABUF_BUFFER != buffer_type) {
+        mmap_read_lock(current->mm);
         vma = find_vma(current->mm, user_address);
+        mmap_read_unlock(current->mm);
         if (IS_ENABLED(HAILO_SUPPORT_MMIO_DMA_MAPPING)) {
             if (NULL == vma) {
                 dev_err(dev, "no vma for virt_addr/size = 0x%08lx/0x%08zx\n", user_address, size);
                 ret = -EFAULT;
-                goto unlock_cleanup;
+                goto cleanup;
             }
         }
 
@@ -180,7 +182,7 @@ struct hailo_vdma_buffer *hailo_vdma_buffer_map(struct device *dev,
             ret = create_fd_from_vma(dev, vma);
             if (ret < 0) {
                 dev_err(dev, "Failed creating fd from vma in given dmabuf\n");
-                goto unlock_cleanup;
+                goto cleanup;
             }
             // Override user address with fd to the dmabuf - like normal dmabuf flow
             user_address = ret;
@@ -213,7 +215,7 @@ struct hailo_vdma_buffer *hailo_vdma_buffer_map(struct device *dev,
         ret = hailo_map_dmabuf(dev, user_address, direction, &sgt, &dmabuf_info);
         if (ret < 0) {
             dev_err(dev, "Failed mapping dmabuf\n");
-            goto unlock_cleanup;
+            goto cleanup;
         }
         // If created dmabuf fd from vma need to decrement refcount and release fd
         if (created_dmabuf_fd_from_vma) {
@@ -235,8 +237,6 @@ struct hailo_vdma_buffer *hailo_vdma_buffer_map(struct device *dev,
         }
     }
 
-    mmap_read_unlock(current->mm);
-
     kref_init(&mapped_buffer->kref);
     mapped_buffer->device = dev;
     mapped_buffer->user_address = user_address;
@@ -252,8 +252,6 @@ struct hailo_vdma_buffer *hailo_vdma_buffer_map(struct device *dev,
     clear_sg_table(&sgt);
 free_buffer_struct:
     kfree(mapped_buffer);
-unlock_cleanup:
-    mmap_read_unlock(current->mm);
 cleanup:
     return ERR_PTR(ret);
 }