drm/nouveau/vm: make vm refcount into a kref

Never used to be required, but a recent change made it necessary.

Reported-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

2 files changed, 11 insertions, 18 deletions

diff --git a/drivers/gpu/drm/nouveau/core/include/subdev/vm.h b/drivers/gpu/drm/nouveau/core/include/subdev/vm.h
index f2e87b105666..fcf57fa309bf 100644
--- a/drivers/gpu/drm/nouveau/core/include/subdev/vm.h
+++ b/drivers/gpu/drm/nouveau/core/include/subdev/vm.h
@@ -55,7 +55,7 @@ struct nouveau_vma {
 struct nouveau_vm {
         struct nouveau_vmmgr *vmm;
         struct nouveau_mm mm;
-        int refcount;
+        struct kref refcount;
 
         struct list_head pgd_list;
         atomic_t engref[NVDEV_SUBDEV_NR];
diff --git a/drivers/gpu/drm/nouveau/core/subdev/vm/base.c b/drivers/gpu/drm/nouveau/core/subdev/vm/base.c
index 67fcb6c852ac..ef3133e7575c 100644
--- a/drivers/gpu/drm/nouveau/core/subdev/vm/base.c
+++ b/drivers/gpu/drm/nouveau/core/subdev/vm/base.c
@@ -361,7 +361,7 @@ nouveau_vm_create(struct nouveau_vmmgr *vmm, u64 offset, u64 length,
 
         INIT_LIST_HEAD(&vm->pgd_list);
         vm->vmm = vmm;
-        vm->refcount = 1;
+        kref_init(&vm->refcount);
         vm->fpde = offset >> (vmm->pgt_bits + 12);
         vm->lpde = (offset + length - 1) >> (vmm->pgt_bits + 12);
 
@@ -441,8 +441,9 @@ nouveau_vm_unlink(struct nouveau_vm *vm, struct nouveau_gpuobj *mpgd)
 }
 
 static void
-nouveau_vm_del(struct nouveau_vm *vm)
+nouveau_vm_del(struct kref *kref)
 {
+        struct nouveau_vm *vm = container_of(kref, typeof(*vm), refcount);
         struct nouveau_vm_pgd *vpgd, *tmp;
 
         list_for_each_entry_safe(vpgd, tmp, &vm->pgd_list, head) {
@@ -458,27 +459,19 @@ int
 nouveau_vm_ref(struct nouveau_vm *ref, struct nouveau_vm **ptr,
                struct nouveau_gpuobj *pgd)
 {
-        struct nouveau_vm *vm;
-        int ret;
-
-        vm = ref;
-        if (vm) {
-                ret = nouveau_vm_link(vm, pgd);
+        if (ref) {
+                int ret = nouveau_vm_link(ref, pgd);
                 if (ret)
                         return ret;
 
-                vm->refcount++;
+                kref_get(&ref->refcount);
         }
 
-        vm = *ptr;
-        *ptr = ref;
-
-        if (vm) {
-                nouveau_vm_unlink(vm, pgd);
-
-                if (--vm->refcount == 0)
-                        nouveau_vm_del(vm);
+        if (*ptr) {
+                nouveau_vm_unlink(*ptr, pgd);
+                kref_put(&(*ptr)->refcount, nouveau_vm_del);
         }
 
+        *ptr = ref;
         return 0;
 }