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Subject[PATCH 3/5] mm: move hmm_vma_fault to nouveau
Date
hmm_vma_fault is marked as a legacy API to get rid of, but seems to suit
the current nouveau flow. Move it to the only user in preparation for
fixing a locking bug involving caller and callee.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ralph Campbell <rcampbell@nvidia.com>
---
drivers/gpu/drm/nouveau/nouveau_svm.c | 54 ++++++++++++++++++++++++++-
include/linux/hmm.h | 54 ---------------------------
2 files changed, 53 insertions(+), 55 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_svm.c b/drivers/gpu/drm/nouveau/nouveau_svm.c
index 9d40114d7949..e831f4184a17 100644
--- a/drivers/gpu/drm/nouveau/nouveau_svm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_svm.c
@@ -36,6 +36,13 @@
#include <linux/sort.h>
#include <linux/hmm.h>

+/*
+ * When waiting for mmu notifiers we need some kind of time out otherwise we
+ * could potentialy wait for ever, 1000ms ie 1s sounds like a long time to
+ * wait already.
+ */
+#define NOUVEAU_RANGE_FAULT_TIMEOUT 1000
+
struct nouveau_svm {
struct nouveau_drm *drm;
struct mutex mutex;
@@ -475,6 +482,51 @@ nouveau_svm_fault_cache(struct nouveau_svm *svm,
fault->inst, fault->addr, fault->access);
}

+static int
+nouveau_range_fault(struct hmm_mirror *mirror, struct hmm_range *range,
+ bool block)
+{
+ long ret;
+
+ /*
+ * With the old API the driver must set each individual entries with
+ * the requested flags (valid, write, ...). So here we set the mask to
+ * keep intact the entries provided by the driver and zero out the
+ * default_flags.
+ */
+ range->default_flags = 0;
+ range->pfn_flags_mask = -1UL;
+
+ ret = hmm_range_register(range, mirror,
+ range->start, range->end,
+ PAGE_SHIFT);
+ if (ret)
+ return (int)ret;
+
+ if (!hmm_range_wait_until_valid(range, NOUVEAU_RANGE_FAULT_TIMEOUT)) {
+ /*
+ * The mmap_sem was taken by driver we release it here and
+ * returns -EAGAIN which correspond to mmap_sem have been
+ * drop in the old API.
+ */
+ up_read(&range->vma->vm_mm->mmap_sem);
+ return -EAGAIN;
+ }
+
+ ret = hmm_range_fault(range, block);
+ if (ret <= 0) {
+ if (ret == -EBUSY || !ret) {
+ /* Same as above, drop mmap_sem to match old API. */
+ up_read(&range->vma->vm_mm->mmap_sem);
+ ret = -EBUSY;
+ } else if (ret == -EAGAIN)
+ ret = -EBUSY;
+ hmm_range_unregister(range);
+ return ret;
+ }
+ return 0;
+}
+
static int
nouveau_svm_fault(struct nvif_notify *notify)
{
@@ -649,7 +701,7 @@ nouveau_svm_fault(struct nvif_notify *notify)
range.values = nouveau_svm_pfn_values;
range.pfn_shift = NVIF_VMM_PFNMAP_V0_ADDR_SHIFT;
again:
- ret = hmm_vma_fault(&svmm->mirror, &range, true);
+ ret = nouveau_range_fault(&svmm->mirror, &range, true);
if (ret == 0) {
mutex_lock(&svmm->mutex);
if (!hmm_range_unregister(&range)) {
diff --git a/include/linux/hmm.h b/include/linux/hmm.h
index 6b55e59fd8e3..657606f48796 100644
--- a/include/linux/hmm.h
+++ b/include/linux/hmm.h
@@ -475,60 +475,6 @@ long hmm_range_dma_unmap(struct hmm_range *range,
dma_addr_t *daddrs,
bool dirty);

-/*
- * HMM_RANGE_DEFAULT_TIMEOUT - default timeout (ms) when waiting for a range
- *
- * When waiting for mmu notifiers we need some kind of time out otherwise we
- * could potentialy wait for ever, 1000ms ie 1s sounds like a long time to
- * wait already.
- */
-#define HMM_RANGE_DEFAULT_TIMEOUT 1000
-
-/* 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)
-{
- long ret;
-
- /*
- * With the old API the driver must set each individual entries with
- * the requested flags (valid, write, ...). So here we set the mask to
- * keep intact the entries provided by the driver and zero out the
- * default_flags.
- */
- range->default_flags = 0;
- range->pfn_flags_mask = -1UL;
-
- ret = hmm_range_register(range, mirror,
- range->start, range->end,
- PAGE_SHIFT);
- if (ret)
- return (int)ret;
-
- if (!hmm_range_wait_until_valid(range, HMM_RANGE_DEFAULT_TIMEOUT)) {
- /*
- * The mmap_sem was taken by driver we release it here and
- * returns -EAGAIN which correspond to mmap_sem have been
- * drop in the old API.
- */
- up_read(&range->vma->vm_mm->mmap_sem);
- return -EAGAIN;
- }
-
- ret = hmm_range_fault(range, block);
- if (ret <= 0) {
- if (ret == -EBUSY || !ret) {
- /* Same as above, drop mmap_sem to match old API. */
- up_read(&range->vma->vm_mm->mmap_sem);
- ret = -EBUSY;
- } else if (ret == -EAGAIN)
- ret = -EBUSY;
- hmm_range_unregister(range);
- return ret;
- }
- return 0;
-}
-
/* Below are for HMM internal use only! Not to be used by device driver! */
static inline void hmm_mm_init(struct mm_struct *mm)
{
--
2.20.1
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