amdgpu: remove -EAGAIN handling for hmm_range_fault

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.

Link: https://lore.kernel.org/r/20190806160554.14046-2-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index 12a59ac83f7271083a3f5f40d1cd49f211693650..f0821638bbc63f134d9c04fde1d936ef9fa7eabe 100644 (file)
--- 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);