[PATCH 18/22] mm: return valid info from hmm_range_unregister

Christoph Hellwig
2019-07-01T06:21:33Z

Checking range->valid is trivial and has no meaningful cost, but
nicely simplifies the fastpath in typical callers. Also remove the
hmm_vma_range_done function, which now is a trivial wrapper around
hmm_range_unregister.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
drivers/gpu/drm/nouveau/nouveau_svm.c | 2 +-
include/linux/hmm.h | 11 +----------
mm/hmm.c | 6 +++++-
3 files changed, 7 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_svm.c b/drivers/gpu/drm/nouveau/nouveau_svm.c
index 8c92374afcf2..9d40114d7949 100644
--- a/drivers/gpu/drm/nouveau/nouveau_svm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_svm.c
@@ -652,7 +652,7 @@ nouveau_svm_fault(struct nvif_notify *notify)
ret = hmm_vma_fault(&svmm->mirror, &range, true);
if (ret == 0) {
mutex_lock(&svmm->mutex);
- if (!hmm_vma_range_done(&range)) {
+ if (!hmm_range_unregister(&range)) {
mutex_unlock(&svmm->mutex);
goto again;
}
diff --git a/include/linux/hmm.h b/include/linux/hmm.h
index 0fa8ea34ccef..4b185d286c3b 100644
--- a/include/linux/hmm.h
+++ b/include/linux/hmm.h
@@ -465,7 +465,7 @@ int hmm_range_register(struct hmm_range *range,
unsigned long start,
unsigned long end,
unsigned page_shift);
-void hmm_range_unregister(struct hmm_range *range);
+bool hmm_range_unregister(struct hmm_range *range);
long hmm_range_snapshot(struct hmm_range *range);
long hmm_range_fault(struct hmm_range *range, bool block);
long hmm_range_dma_map(struct hmm_range *range,
@@ -487,15 +487,6 @@ long hmm_range_dma_unmap(struct hmm_range *range,
*/
#define HMM_RANGE_DEFAULT_TIMEOUT 1000

-/* This is a temporary helper to avoid merge conflict between trees. */
-static inline bool hmm_vma_range_done(struct hmm_range *range)
-{
- bool ret = hmm_range_valid(range);
-
- hmm_range_unregister(range);
- return ret;
-}
-
/* This is a temporary helper to avoid merge conflict between trees. */
static inline int hmm_vma_fault(struct hmm_mirror *mirror,
struct hmm_range *range, bool block)
diff --git a/mm/hmm.c b/mm/hmm.c
index de35289df20d..c85ed7d4e2ce 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -920,11 +920,14 @@ EXPORT_SYMBOL(hmm_range_register);
*
* Range struct is used to track updates to the CPU page table after a call to
* hmm_range_register(). See include/linux/hmm.h for how to use it.
+ *
+ * Returns if the range was still valid at the time of unregistering.
*/
-void hmm_range_unregister(struct hmm_range *range)
+bool hmm_range_unregister(struct hmm_range *range)
{
struct hmm *hmm = range->hmm;
unsigned long flags;
+ bool ret = range->valid;

spin_lock_irqsave(&hmm->ranges_lock, flags);
list_del_init(&range->list);
@@ -941,6 +944,7 @@ void hmm_range_unregister(struct hmm_range *range)
*/
range->valid = false;
memset(&range->hmm, POISON_INUSE, sizeof(range->hmm));
+ return ret;
}
EXPORT_SYMBOL(hmm_range_unregister);

--
2.20.1