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media: staging: media: atomisp: Use kmap_local_page() in hmm_store()

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The use of kmap() is being deprecated in favor of kmap_local_page()
where it is feasible. The same is true for kmap_atomic().

In file pci/hmm/hmm.c, function hmm_store() test if we are in atomic
context and, if so, it calls kmap_atomic(), if not, it calls kmap().

First of all, in_atomic() shouldn't be used in drivers. This macro
cannot always detect atomic context; in particular, it cannot know
about held spinlocks in non-preemptible kernels.

Notwithstanding what it is said above, this code doesn't need to care
whether or not it is executing in atomic context. It can simply use
kmap_local_page() / kunmap_local() that can instead do the mapping /
unmapping regardless of the context.

With kmap_local_page(), the mapping is per thread, CPU local and not
globally visible. Therefore, hmm_store()() is a function where the use
of kmap_local_page() in place of both kmap() and kmap_atomic() is
correctly suited.

Convert the calls of kmap() / kunmap() and kmap_atomic() /
kunmap_atomic() to kmap_local_page() / kunmap_local() and drop the
unnecessary tests which test if the code is in atomic context.

Link: https://lore.kernel.org/linux-media/20220413225531.9425-1-fmdefrancesco@gmail.com
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Tested-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
This commit is contained in:
Fabio M. De Francesco 2022-04-13 23:55:31 +01:00 committed by Mauro Carvalho Chehab
parent aab1c42a9d
commit ce2203e7d6
1 changed files with 2 additions and 12 deletions
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14
drivers/staging/media/atomisp/pci/hmm/hmm.c
View file

@ -427,10 +427,7 @@ int hmm_store(ia_css_ptr virt, const void *data, unsigned int bytes)
idx = (virt - bo->start) >> PAGE_SHIFT;
offset = (virt - bo->start) - (idx << PAGE_SHIFT);
if (in_atomic())
des = (char *)kmap_atomic(bo->pages[idx]);
else
des = (char *)kmap(bo->pages[idx]);
des = (char *)kmap_local_page(bo->pages[idx]);
if (!des) {
dev_err(atomisp_dev,
@ -457,14 +454,7 @@ int hmm_store(ia_css_ptr virt, const void *data, unsigned int bytes)
clflush_cache_range(des, len);
if (in_atomic())
/*
* Note: kunmap_atomic requires return addr from
* kmap_atomic, not the page. See linux/highmem.h
*/
kunmap_atomic(des - offset);
else
kunmap(bo->pages[idx]);
kunmap_local(des);
}
return 0;