[lkml]   [2022]   [Apr]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
Patch in this message
Subject[PATCH v2 1/3] binder: Use memset_page() in binder_alloc_clear_buf()
The use of kmap() is being deprecated in favor of kmap_local_page()
where it is feasible. With kmap_local_page(), the mapping is per
thread, CPU local and not globally visible.

binder_alloc_clear_buf() is a function where the use of kmap_local_page()
in place of kmap() is correctly suited because the mapping is local to the

Therefore, use kmap_local_page() / kunmap_local() but, instead of open
coding these two functions and adding a memset() of the virtual address
of the mapping, prefer memset_page().

Cc: Christophe JAILLET <>
Acked-by: Todd Kjos <>
Signed-off-by: Fabio M. De Francesco <>

v1->v2: Add Todd Kjos's tag in the commit message (thanks!)

drivers/android/binder_alloc.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c
index 2ac1008a5f39..0b3f2f569053 100644
--- a/drivers/android/binder_alloc.c
+++ b/drivers/android/binder_alloc.c
@@ -1175,14 +1175,11 @@ static void binder_alloc_clear_buf(struct binder_alloc *alloc,
unsigned long size;
struct page *page;
pgoff_t pgoff;
- void *kptr;

page = binder_alloc_get_page(alloc, buffer,
buffer_offset, &pgoff);
size = min_t(size_t, bytes, PAGE_SIZE - pgoff);
- kptr = kmap(page) + pgoff;
- memset(kptr, 0, size);
- kunmap(page);
+ memset_page(page, pgoff, 0, size);
bytes -= size;
buffer_offset += size;
 \ /
  Last update: 2022-04-25 19:59    [W:0.059 / U:0.164 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site