Deprecate kmap() in favor of kmap_local_page() due to high
cost, restricted mapping space, the overhead of a global lock
for synchronization, and making the process sleep in the
absence of free slots.
kmap_local_page() offers thread-local and CPU-local mappings,
take pagefaults in a local kmap region and preserves preemption
by saving the mappings of outgoing task and restoring those of
the incoming one during a context switch.
It is faster than kmap(), and in functions "dmirror_do_read" and
"dmirror_do_write" the mappings are kept local to the thread.
Therefore, replace kmap/mem*()/kunmap pattern with
memcpy_to/from_page() and remove the unused variable "tmp".
Signed-off-by: Sumitra Sharma <sumitraartsy@xxxxxxxxx>
---
Suggested-by: Fabio M. De Francesco <fmdefrancesco@xxxxxxxxx>
lib/test_hmm.c | 10 ++--------
1 file changed, 2 insertions(+), 8 deletions(-)
diff --git a/lib/test_hmm.c b/lib/test_hmm.c
index 67e6f83fe0f8..cc96dfa54122 100644
--- a/lib/test_hmm.c
+++ b/lib/test_hmm.c
@@ -368,16 +368,13 @@ static int dmirror_do_read(struct dmirror *dmirror, unsigned long start,
for (pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++) {
void *entry;
struct page *page;
- void *tmp;
entry = xa_load(&dmirror->pt, pfn);
page = xa_untag_pointer(entry);
if (!page)
return -ENOENT;
- tmp = kmap(page);
- memcpy(ptr, tmp, PAGE_SIZE);
- kunmap(page);
+ memcpy_from_page((char *)ptr, page, 0, PAGE_SIZE);
ptr += PAGE_SIZE;
bounce->cpages++;
@@ -437,16 +434,13 @@ static int dmirror_do_write(struct dmirror *dmirror, unsigned long start,
for (pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++) {
void *entry;
struct page *page;
- void *tmp;
entry = xa_load(&dmirror->pt, pfn);
page = xa_untag_pointer(entry);
if (!page || xa_pointer_tag(entry) != DPT_XA_TAG_WRITE)
return -ENOENT;
- tmp = kmap(page);
- memcpy(tmp, ptr, PAGE_SIZE);
- kunmap(page);
+ memcpy_to_page(page, 0, (char *)ptr, PAGE_SIZE);
ptr += PAGE_SIZE;
bounce->cpages++;
--
2.25.1
