Verify 'drm_agp' is not NULL for all its wrappers - this causes no overhead

    and must be done if in future a driver tries to talk to the AGP
    directly from kernelspace instead of userspace, and the AGP is not
    present.

diff --git a/linux/drm_agp_tmp.h b/linux/drm_agp_tmp.h
index 2418d79..8ae64b1 100644 (file)
--- a/linux/drm_agp_tmp.h
+++ b/linux/drm_agp_tmp.h
@@ -62,6 +62,8 @@ static const drm_agp_t *drm_agp = NULL;
  */
 int DRM(agp_acquire)(void)
 {
+       if (!drm_agp || !drm_agp->acquire)
+               return -EINVAL;
        return drm_agp->acquire();
 }
 
@@ -70,8 +72,9 @@ int DRM(agp_acquire)(void)
  */
 void DRM(agp_release)(void)
 {
-       if (drm_agp->release)
-               drm_agp->release();
+       if (!drm_agp || !drm_agp->release)
+               return;
+       drm_agp->release();
 }
 
 /**
@@ -79,8 +82,9 @@ void DRM(agp_release)(void)
  */
 void DRM(agp_enable)(unsigned long mode)
 {
-       if (drm_agp->enable)
-               drm_agp->enable(mode);
+       if (!drm_agp || !drm_agp->enable)
+               return;
+       drm_agp->enable(mode);
 }
 
 /** 
@@ -91,7 +95,7 @@ void DRM(agp_enable)(unsigned long mode)
  */
 agp_memory *DRM(agp_allocate_memory)(size_t pages, u32 type)
 {
-       if (!drm_agp->allocate_memory) 
+       if (!drm_agp || !drm_agp->allocate_memory)
                return NULL;
        return drm_agp->allocate_memory(pages, type);
 }
@@ -104,7 +108,7 @@ agp_memory *DRM(agp_allocate_memory)(size_t pages, u32 type)
  */
 int DRM(agp_free_memory)(agp_memory *handle)
 {
-       if (!handle || !drm_agp->free_memory) 
+       if (!handle || !drm_agp || !drm_agp->free_memory) 
                return 0;
        drm_agp->free_memory(handle);
        return 1;
@@ -118,7 +122,7 @@ int DRM(agp_free_memory)(agp_memory *handle)
  */
 int DRM(agp_bind_memory)(agp_memory *handle, off_t start)
 {
-       if (!handle || !drm_agp->bind_memory) 
+       if (!handle || !drm_agp || !drm_agp->bind_memory) 
                return -EINVAL;
        return drm_agp->bind_memory(handle, start);
 }
@@ -131,7 +135,7 @@ int DRM(agp_bind_memory)(agp_memory *handle, off_t start)
  */
 int DRM(agp_unbind_memory)(agp_memory *handle)
 {
-       if (!handle || !drm_agp->unbind_memory)
+       if (!handle || !drm_agp || !drm_agp->unbind_memory)
                return -EINVAL;
        return drm_agp->unbind_memory(handle);
 }