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Subject[PATCH 01/15] amdgpu: remove -EAGAIN handling for hmm_range_fault
Date
hmm_range_fault can only return -EAGAIN if called with the
HMM_FAULT_ALLOW_RETRY flag, which amdgpu never does. Remove the
handling for the -EAGAIN case with its non-standard locking scheme.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 23 +++--------------------
1 file changed, 3 insertions(+), 20 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index 12a59ac83f72..f0821638bbc6 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -778,7 +778,6 @@ int amdgpu_ttm_tt_get_user_pages(struct amdgpu_bo *bo, struct page **pages)
struct hmm_range *range;
unsigned long i;
uint64_t *pfns;
- int retry = 0;
int r = 0;

if (!mm) /* Happens during process shutdown */
@@ -822,7 +821,6 @@ int amdgpu_ttm_tt_get_user_pages(struct amdgpu_bo *bo, struct page **pages)
hmm_range_register(range, mirror, start,
start + ttm->num_pages * PAGE_SIZE, PAGE_SHIFT);

-retry:
/*
* Just wait for range to be valid, safe to ignore return value as we
* will use the return value of hmm_range_fault() below under the
@@ -831,24 +829,12 @@ int amdgpu_ttm_tt_get_user_pages(struct amdgpu_bo *bo, struct page **pages)
hmm_range_wait_until_valid(range, HMM_RANGE_DEFAULT_TIMEOUT);

down_read(&mm->mmap_sem);
-
r = hmm_range_fault(range, 0);
- if (unlikely(r < 0)) {
- if (likely(r == -EAGAIN)) {
- /*
- * return -EAGAIN, mmap_sem is dropped
- */
- if (retry++ < MAX_RETRY_HMM_RANGE_FAULT)
- goto retry;
- else
- pr_err("Retry hmm fault too many times\n");
- }
-
- goto out_up_read;
- }
-
up_read(&mm->mmap_sem);

+ if (unlikely(r < 0))
+ goto out_free_pfns;
+
for (i = 0; i < ttm->num_pages; i++) {
pages[i] = hmm_device_entry_to_page(range, pfns[i]);
if (unlikely(!pages[i])) {
@@ -864,9 +850,6 @@ int amdgpu_ttm_tt_get_user_pages(struct amdgpu_bo *bo, struct page **pages)

return 0;

-out_up_read:
- if (likely(r != -EAGAIN))
- up_read(&mm->mmap_sem);
out_free_pfns:
hmm_range_unregister(range);
kvfree(pfns);
--
2.20.1
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