From: Colin Ian King colin.king@canonical.com
cppcheck on lines 917 and 977 show an ineffective assignment to the dma buffer pointer:
[drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c:917]: [drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c:977]: (warning) Assignment of function parameter has no effect outside the function. Did you forget dereferencing it?
On a successful DMA buffer lookup, the dma buffer pointer is assigned, however, on failure it currently is left in an undefined state.
The original intention in the error exit path was to nullify the pointer on an error (which the original code failed to do properly). This patch fixes this also ensures all failure paths nullify the buffer pointer on the error return.
Fortunately the callers to vmw_translate_mob_ptr and vmw_translate_guest_ptr are checking on a return status and not on the dma buffer pointer, so the original code worked.
Signed-off-by: Colin Ian King colin.king@canonical.com --- drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c index 33176d0..275149c 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c @@ -890,7 +890,8 @@ static int vmw_translate_mob_ptr(struct vmw_private *dev_priv, ret = vmw_user_dmabuf_lookup(sw_context->fp->tfile, handle, &vmw_bo); if (unlikely(ret != 0)) { DRM_ERROR("Could not find or use MOB buffer.\n"); - return -EINVAL; + ret = -EINVAL; + goto out_no_reloc; } bo = &vmw_bo->base;
@@ -914,7 +915,7 @@ static int vmw_translate_mob_ptr(struct vmw_private *dev_priv,
out_no_reloc: vmw_dmabuf_unreference(&vmw_bo); - vmw_bo_p = NULL; + *vmw_bo_p = NULL; return ret; }
@@ -951,7 +952,8 @@ static int vmw_translate_guest_ptr(struct vmw_private *dev_priv, ret = vmw_user_dmabuf_lookup(sw_context->fp->tfile, handle, &vmw_bo); if (unlikely(ret != 0)) { DRM_ERROR("Could not find or use GMR region.\n"); - return -EINVAL; + ret = -EINVAL; + goto out_no_reloc; } bo = &vmw_bo->base;
@@ -974,7 +976,7 @@ static int vmw_translate_guest_ptr(struct vmw_private *dev_priv,
out_no_reloc: vmw_dmabuf_unreference(&vmw_bo); - vmw_bo_p = NULL; + *vmw_bo_p = NULL; return ret; }