The patch titled
/dev/zero: avoid repeated access_ok() checks
has been added to the -mm tree. Its filename is
dev-zero-avoid-repeated-access_ok-checks.patch
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------------------------------------------------------
Subject: /dev/zero: avoid repeated access_ok() checks
From: Nikanth Karthikesan <knikanth@xxxxxxx>
In read_zero, we check for access_ok() once for the count bytes. It is
unnecessarily checked again in clear_user. Use __clear_user, which does
not check for access_ok().
Signed-off-by: Nikanth Karthikesan <knikanth@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/char/mem.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN drivers/char/mem.c~dev-zero-avoid-repeated-access_ok-checks drivers/char/mem.c
--- a/drivers/char/mem.c~dev-zero-avoid-repeated-access_ok-checks
+++ a/drivers/char/mem.c
@@ -690,7 +690,7 @@ static ssize_t read_zero(struct file * f
if (chunk > PAGE_SIZE)
chunk = PAGE_SIZE; /* Just for latency reasons */
- unwritten = clear_user(buf, chunk);
+ unwritten = __clear_user(buf, chunk);
written += chunk - unwritten;
if (unwritten)
break;
_
Patches currently in -mm which might be from knikanth@xxxxxxx are
dev-zero-avoid-repeated-access_ok-checks.patch
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