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.
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@xxxxxxxxx>
---
drivers/staging/media/atomisp/pci/hmm/hmm.c | 14 ++------------
1 file changed, 2 insertions(+), 12 deletions(-)
diff --git a/drivers/staging/media/atomisp/pci/hmm/hmm.c b/drivers/staging/media/atomisp/pci/hmm/hmm.c
index 46ac082cd3f1..54188197c3dc 100644
--- a/drivers/staging/media/atomisp/pci/hmm/hmm.c
+++ b/drivers/staging/media/atomisp/pci/hmm/hmm.c
@@ -482,10 +482,7 @@ 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->page_obj[idx].page);
- else
- des = (char *)kmap(bo->page_obj[idx].page);
+ des = (char *)kmap_local_page(bo->page_obj[idx].page);
if (!des) {
dev_err(atomisp_dev,
@@ -512,14 +509,7 @@ 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->page_obj[idx].page);
+ kunmap_local(des);
}
return 0;
--
2.34.1
