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/dev/zero: avoid repeated access_ok() checks

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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@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Nikanth Karthikesan 2009-09-23 15:57:09 -07:00 committed by Linus Torvalds
parent 0b8c78f2bf
commit bb521c5de0
1 changed files with 1 additions and 1 deletions
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2
drivers/char/mem.c
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@ -690,7 +690,7 @@ static ssize_t read_zero(struct file * file, char __user * buf,
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;