drivers: pci: hailo: Fix kernel warning when calling find_vdma()

Calling this function without holding the mmap_read_lock causes the
kernel to throw an error message, spamming the dmesg logs when running
the Hailo hardware.

Fix it by adding the approprite lock/unlock functions around find_vdma().

Signed-off-by: Naushir Patuck <naush@raspberrypi.com>

Author: naushir

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

@@ -163,13 +163,14 @@ struct hailo_vdma_buffer *hailo_vdma_buffer_map(struct device *dev,
         goto cleanup;
     }
 
+    mmap_read_lock(current->mm);
     if (HAILO_DMA_DMABUF_BUFFER != buffer_type) {
         vma = find_vma(current->mm, user_address);
         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 cleanup;
+                goto unlock_cleanup;
             }
         }
 
@@ -179,7 +180,7 @@ 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 cleanup;
+                goto unlock_cleanup;
             }
             // Override user address with fd to the dmabuf - like normal dmabuf flow
             user_address = ret;
@@ -212,7 +213,7 @@ 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 cleanup;
+            goto unlock_cleanup;
         }
         // If created dmabuf fd from vma need to decrement refcount and release fd
         if (created_dmabuf_fd_from_vma) {
@@ -234,6 +235,8 @@ 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;
@@ -249,6 +252,8 @@ 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);
 }