Am 03.03.21 um 14:20 schrieb Thomas Gleixner:
From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
There is no reason to disable pagefaults and preemption as a side effect of
kmap_atomic_prot().
Use kmap_local_page_prot() instead and document the reasoning for the
mapping usage with the given pgprot.
Remove the NULL pointer check for the map. These functions return a valid
address for valid pages and the return was bogus anyway as it would have
left preemption and pagefaults disabled.
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Christian Koenig <christian.koenig@xxxxxxx>
Cc: Huang Rui <ray.huang@xxxxxxx>
Cc: David Airlie <airlied@xxxxxxxx>
Cc: Daniel Vetter <daniel@xxxxxxxx>
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
---
drivers/gpu/drm/ttm/ttm_bo_util.c | 20 ++++++++++++--------
1 file changed, 12 insertions(+), 8 deletions(-)
--- a/drivers/gpu/drm/ttm/ttm_bo_util.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
@@ -181,13 +181,15 @@ static int ttm_copy_io_ttm_page(struct t
return -ENOMEM;
src = (void *)((unsigned long)src + (page << PAGE_SHIFT));
- dst = kmap_atomic_prot(d, prot);
- if (!dst)
- return -ENOMEM;
+ /*
+ * Ensure that a highmem page is mapped with the correct
+ * pgprot. For non highmem the mapping is already there.
+ */
I find the comment a bit misleading. Maybe write:
/*
* Locally map highmem pages with the correct pgprot.
* Normal memory should already have the correct pgprot in the linear
mapping.
*/
Apart from that looks good to me.
Regards,
Christian.
+ dst = kmap_local_page_prot(d, prot);
memcpy_fromio(dst, src, PAGE_SIZE);
- kunmap_atomic(dst);
+ kunmap_local(dst);
return 0;
}
@@ -203,13 +205,15 @@ static int ttm_copy_ttm_io_page(struct t
return -ENOMEM;
dst = (void *)((unsigned long)dst + (page << PAGE_SHIFT));
- src = kmap_atomic_prot(s, prot);
- if (!src)
- return -ENOMEM;
+ /*
+ * Ensure that a highmem page is mapped with the correct
+ * pgprot. For non highmem the mapping is already there.
+ */
+ src = kmap_local_page_prot(s, prot);
memcpy_toio(dst, src, PAGE_SIZE);
- kunmap_atomic(src);
+ kunmap_local(src);
return 0;
}
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