From: Zhao Liu <[email protected]>
The use of kmap_atomic() is being deprecated in favor of
kmap_local_page()[1].
The main difference between atomic and local mappings is that local
mappings doesn't disable page faults or preemption.
In drm/i915/gt/uc/intel_us_fw.c, the function intel_uc_fw_copy_rsa()
just use the mapping to do memory copy so it doesn't need to disable
pagefaults and preemption for mapping. Thus the local mapping without
atomic context (not disable pagefaults / preemption) is enough.
Therefore, intel_uc_fw_copy_rsa() is a function where the use of
memcpy_from_page() with kmap_local_page() in place of memcpy() with
kmap_atomic() is correctly suited.
Convert the calls of memcpy() with kmap_atomic() / kunmap_atomic() to
memcpy_from_page() which uses local mapping to copy.
[1]: https://lore.kernel.org/all/[email protected]/T/#u
Suggested-by: Ira Weiny <[email protected]>
Suggested-by: Fabio M. De Francesco <[email protected]>
Signed-off-by: Zhao Liu <[email protected]>
---
Suggested by credits:
Ira: Referred to his task document and suggestions about using
memcpy_from_page() directly.
Fabio: Referred to his boiler plate commit message.
---
drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c b/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c
index b91ad4aede1f..64d56f175d32 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c
@@ -962,16 +962,13 @@ size_t intel_uc_fw_copy_rsa(struct intel_uc_fw *uc_fw, void *dst, u32 max_len)
for_each_sgt_page(page, iter, uc_fw->obj->mm.pages) {
u32 len = min_t(u32, size, PAGE_SIZE - offset);
- void *vaddr;
if (idx > 0) {
idx--;
continue;
}
- vaddr = kmap_atomic(page);
- memcpy(dst, vaddr + offset, len);
- kunmap_atomic(vaddr);
+ memcpy_from_page(dst, page, offset, len);
offset = 0;
dst += len;
--
2.34.1
On Mon, Oct 17, 2022 at 05:37:23PM +0800, Zhao Liu wrote:
> From: Zhao Liu <[email protected]>
>
> The use of kmap_atomic() is being deprecated in favor of
> kmap_local_page()[1].
>
> The main difference between atomic and local mappings is that local
> mappings doesn't disable page faults or preemption.
>
> In drm/i915/gt/uc/intel_us_fw.c, the function intel_uc_fw_copy_rsa()
> just use the mapping to do memory copy so it doesn't need to disable
> pagefaults and preemption for mapping. Thus the local mapping without
> atomic context (not disable pagefaults / preemption) is enough.
>
> Therefore, intel_uc_fw_copy_rsa() is a function where the use of
> memcpy_from_page() with kmap_local_page() in place of memcpy() with
> kmap_atomic() is correctly suited.
>
> Convert the calls of memcpy() with kmap_atomic() / kunmap_atomic() to
> memcpy_from_page() which uses local mapping to copy.
>
> [1]: https://lore.kernel.org/all/[email protected]/T/#u
>
> Suggested-by: Ira Weiny <[email protected]>
Reviewed-by: Ira Weiny <[email protected]>
> Suggested-by: Fabio M. De Francesco <[email protected]>
> Signed-off-by: Zhao Liu <[email protected]>
> ---
> Suggested by credits:
> Ira: Referred to his task document and suggestions about using
> memcpy_from_page() directly.
> Fabio: Referred to his boiler plate commit message.
> ---
> drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c | 5 +----
> 1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c b/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c
> index b91ad4aede1f..64d56f175d32 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c
> @@ -962,16 +962,13 @@ size_t intel_uc_fw_copy_rsa(struct intel_uc_fw *uc_fw, void *dst, u32 max_len)
>
> for_each_sgt_page(page, iter, uc_fw->obj->mm.pages) {
> u32 len = min_t(u32, size, PAGE_SIZE - offset);
> - void *vaddr;
>
> if (idx > 0) {
> idx--;
> continue;
> }
>
> - vaddr = kmap_atomic(page);
> - memcpy(dst, vaddr + offset, len);
> - kunmap_atomic(vaddr);
> + memcpy_from_page(dst, page, offset, len);
>
> offset = 0;
> dst += len;
> --
> 2.34.1
>