[PATCH 2/4] fixup! drm/nouveau: use hmm_range_fault_unlocked_timeout() for SVM faults

[Stanislav Kinsburskii]

nouveau_range_fault() now uses hmm_range_fault_unlocked_timeout() for
the HMM fault path. The timeout passed to that helper is meant to bound
HMM's internal mmu-notifier retry loop, not the whole nouveau retry loop
around mmu_interval_read_retry().

Pass the full relative HMM_RANGE_DEFAULT_TIMEOUT value to
hmm_range_fault_unlocked_timeout() on each attempt, and retry from the
nouveau-side mmu_interval_read_retry() check with a fresh HMM retry
budget. This lets HMM continue when it has made progress, while still
preserving a timeout for repeated notifier invalidation retries inside
one HMM fault attempt.

This also removes the open-coded absolute deadline and remaining-time
calculation from nouveau_range_fault().

Signed-off-by: Stanislav Kinsburskii <skinsburs...@gmail.com>
---
 drivers/gpu/drm/nouveau/nouveau_svm.c |   30 ++++++++++--------------------
 1 file changed, 10 insertions(+), 20 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_svm.c 
b/drivers/gpu/drm/nouveau/nouveau_svm.c
index 4cfb6eb7c771..b1415c2e49fc 100644
--- a/drivers/gpu/drm/nouveau/nouveau_svm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_svm.c
@@ -655,8 +655,7 @@ static int nouveau_range_fault(struct nouveau_svmm *svmm,
                               unsigned long hmm_flags,
                               struct svm_notifier *notifier)
 {
-       unsigned long timeout =
-               jiffies + msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT);
+       unsigned long timeout = msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT);
        /* Have HMM fault pages within the fault window to the GPU. */
        unsigned long hmm_pfns[1];
        struct hmm_range range = {
@@ -677,25 +676,16 @@ static int nouveau_range_fault(struct nouveau_svmm *svmm,
        range.start = notifier->notifier.interval_tree.start;
        range.end = notifier->notifier.interval_tree.last + 1;
 
-       while (true) {
-               if (time_after(jiffies, timeout)) {
-                       ret = -EBUSY;
-                       goto out;
-               }
-
-               ret = hmm_range_fault_unlocked_timeout(&range,
-                                                      max(timeout - jiffies,
-                                                          1L));
-               if (ret)
-                       goto out;
+again:
+       ret = hmm_range_fault_unlocked_timeout(&range, timeout);
+       if (ret)
+               goto out;
 
-               mutex_lock(&svmm->mutex);
-               if (mmu_interval_read_retry(range.notifier,
-                                           range.notifier_seq)) {
-                       mutex_unlock(&svmm->mutex);
-                       continue;
-               }
-               break;
+       mutex_lock(&svmm->mutex);
+       if (mmu_interval_read_retry(range.notifier,
+                                   range.notifier_seq)) {
+               mutex_unlock(&svmm->mutex);
+               goto again;
        }
 
        nouveau_hmm_convert_pfn(drm, &range, args);