svn commit: r297231 - in head/sys/dev/drm2: i915 ttm

[Konstantin Belousov]

Author: kib
Date: Thu Mar 24 09:56:53 2016
New Revision: 297231
URL: https://svnweb.freebsd.org/changeset/base/297231

Log:
  Handle the driver KPI change from r292373.  Ensure that managed device
  pagers fault routines always return with a result page, be it the
  proper and valid result page, or initially passed freshly allocated
  placeholder.  Do not free the passed in page until we are able to
  provide the replacement, and do not assign NULL to *mres.
  
  Reported and tested by:	dumbbell
  Reviewed by:	royger (who also verified that Xen code is safe)
  Sponsored by:	The FreeBSD Foundation

Modified:
  head/sys/dev/drm2/i915/i915_gem.c
  head/sys/dev/drm2/ttm/ttm_bo_vm.c

Modified: head/sys/dev/drm2/i915/i915_gem.c
==============================================================================
--- head/sys/dev/drm2/i915/i915_gem.c	Thu Mar 24 09:55:11 2016	(r297230)
+++ head/sys/dev/drm2/i915/i915_gem.c	Thu Mar 24 09:56:53 2016	(r297231)
@@ -1481,7 +1481,7 @@ i915_gem_pager_fault(vm_object_t vm_obj,
 	struct drm_i915_gem_object *obj = to_intel_bo(gem_obj);
 	struct drm_device *dev = obj->base.dev;
 	drm_i915_private_t *dev_priv = dev->dev_private;
-	vm_page_t page, oldpage;
+	vm_page_t page;
 	int ret = 0;
 #ifdef FREEBSD_WIP
 	bool write = (prot & VM_PROT_WRITE) != 0;
@@ -1504,13 +1504,10 @@ i915_gem_pager_fault(vm_object_t vm_obj,
 	 * progress.
 	 */
 	if (*mres != NULL) {
-		oldpage = *mres;
-		vm_page_lock(oldpage);
-		vm_page_remove(oldpage);
-		vm_page_unlock(oldpage);
-		*mres = NULL;
-	} else
-		oldpage = NULL;
+		vm_page_lock(*mres);
+		vm_page_remove(*mres);
+		vm_page_unlock(*mres);
+	}
 	VM_OBJECT_WUNLOCK(vm_obj);
 retry:
 	ret = 0;
@@ -1590,7 +1587,6 @@ retry:
 	}
 	page->valid = VM_PAGE_BITS_ALL;
 have_page:
-	*mres = page;
 	vm_page_xbusy(page);
 
 	CTR4(KTR_DRM, "fault %p %jx %x phys %x", gem_obj, offset, prot,
@@ -1603,11 +1599,13 @@ have_page:
 		i915_gem_object_unpin(obj);
 	}
 	DRM_UNLOCK(dev);
-	if (oldpage != NULL) {
-		vm_page_lock(oldpage);
-		vm_page_free(oldpage);
-		vm_page_unlock(oldpage);
+	if (*mres != NULL) {
+		KASSERT(*mres != page, ("loosing %p %p", *mres, page));
+		vm_page_lock(*mres);
+		vm_page_free(*mres);
+		vm_page_unlock(*mres);
 	}
+	*mres = page;
 	vm_object_pip_wakeup(vm_obj);
 	return (VM_PAGER_OK);
 

Modified: head/sys/dev/drm2/ttm/ttm_bo_vm.c
==============================================================================
--- head/sys/dev/drm2/ttm/ttm_bo_vm.c	Thu Mar 24 09:55:11 2016	(r297230)
+++ head/sys/dev/drm2/ttm/ttm_bo_vm.c	Thu Mar 24 09:56:53 2016	(r297231)
@@ -106,21 +106,18 @@ ttm_bo_vm_fault(vm_object_t vm_obj, vm_o
 	struct ttm_buffer_object *bo = vm_obj->handle;
 	struct ttm_bo_device *bdev = bo->bdev;
 	struct ttm_tt *ttm = NULL;
-	vm_page_t m, m1, oldm;
+	vm_page_t m, m1;
 	int ret;
 	int retval = VM_PAGER_OK;
 	struct ttm_mem_type_manager *man =
 		&bdev->man[bo->mem.mem_type];
 
 	vm_object_pip_add(vm_obj, 1);
-	oldm = *mres;
-	if (oldm != NULL) {
-		vm_page_lock(oldm);
-		vm_page_remove(oldm);
-		vm_page_unlock(oldm);
-		*mres = NULL;
-	} else
-		oldm = NULL;
+	if (*mres != NULL) {
+		vm_page_lock(*mres);
+		vm_page_remove(*mres);
+		vm_page_unlock(*mres);
+	}
 retry:
 	VM_OBJECT_WUNLOCK(vm_obj);
 	m = NULL;
@@ -261,14 +258,14 @@ reserve:
 		    bo, m, m1, (uintmax_t)offset));
 	}
 	m->valid = VM_PAGE_BITS_ALL;
-	*mres = m;
 	vm_page_xbusy(m);
-
-	if (oldm != NULL) {
-		vm_page_lock(oldm);
-		vm_page_free(oldm);
-		vm_page_unlock(oldm);
+	if (*mres != NULL) {
+		KASSERT(*mres != m, ("loosing %p %p", *mres, m));
+		vm_page_lock(*mres);
+		vm_page_free(*mres);
+		vm_page_unlock(*mres);
 	}
+	*mres = m;
 
 out_io_unlock1:
 	ttm_mem_io_unlock(man);