[patch 1/3 -next] drm/vc4: copy_to_user() returns the number of bytes remaining

[Dan Carpenter]

The copy_to/from_user() functions return the number of bytes remaining
to be copied.  We want to return error codes here.

Also it's a bad idea to print an error message if a copy from user fails
because users can use that to spam /var/log/messages which is annoying
so I removed those.

Fixes: 214613656b51 ('drm/vc4: Add an interface for capturing the GPU state 
after a hang.')
Signed-off-by: Dan Carpenter <dan.carpenter at oracle.com>

diff --git a/drivers/gpu/drm/vc4/vc4_gem.c b/drivers/gpu/drm/vc4/vc4_gem.c
index 39f29e7..461a16c 100644
--- a/drivers/gpu/drm/vc4/vc4_gem.c
+++ b/drivers/gpu/drm/vc4/vc4_gem.c
@@ -71,7 +71,7 @@ vc4_get_hang_state_ioctl(struct drm_device *dev, void *data,
        struct vc4_dev *vc4 = to_vc4_dev(dev);
        unsigned long irqflags;
        u32 i;
-       int ret;
+       int ret = 0;

        spin_lock_irqsave(&vc4->job_lock, irqflags);
        kernel_state = vc4->hang_state;
@@ -119,9 +119,11 @@ vc4_get_hang_state_ioctl(struct drm_device *dev, void 
*data,
                bo_state[i].size = vc4_bo->base.base.size;
        }

-       ret = copy_to_user((void __user *)(uintptr_t)get_state->bo,
-                          bo_state,
-                          state->bo_count * sizeof(*bo_state));
+       if (copy_to_user((void __user *)(uintptr_t)get_state->bo,
+                        bo_state,
+                        state->bo_count * sizeof(*bo_state)))
+               ret = -EFAULT;
+
        kfree(bo_state);

 err_free:
@@ -554,27 +556,24 @@ vc4_get_bcl(struct drm_device *dev, struct vc4_exec_info 
*exec)
        exec->shader_state = temp + exec_size;
        exec->shader_state_size = args->shader_rec_count;

-       ret = copy_from_user(bin,
-                            (void __user *)(uintptr_t)args->bin_cl,
-                            args->bin_cl_size);
-       if (ret) {
-               DRM_ERROR("Failed to copy in bin cl\n");
+       if (copy_from_user(bin,
+                          (void __user *)(uintptr_t)args->bin_cl,
+                          args->bin_cl_size)) {
+               ret = -EFAULT;
                goto fail;
        }

-       ret = copy_from_user(exec->shader_rec_u,
-                            (void __user *)(uintptr_t)args->shader_rec,
-                            args->shader_rec_size);
-       if (ret) {
-               DRM_ERROR("Failed to copy in shader recs\n");
+       if (copy_from_user(exec->shader_rec_u,
+                          (void __user *)(uintptr_t)args->shader_rec,
+                          args->shader_rec_size)) {
+               ret = -EFAULT;
                goto fail;
        }

-       ret = copy_from_user(exec->uniforms_u,
-                            (void __user *)(uintptr_t)args->uniforms,
-                            args->uniforms_size);
-       if (ret) {
-               DRM_ERROR("Failed to copy in uniforms cl\n");
+       if (copy_from_user(exec->uniforms_u,
+                          (void __user *)(uintptr_t)args->uniforms,
+                          args->uniforms_size)) {
+               ret = -EFAULT;
                goto fail;
        }