[PATCH][BUG] fix memory leak on reading cpuset files after seeking beyond eof

[KUROSAWA Takahiro <kurosawa@valinux.co.jp>]

On Tue, 27 Sep 2005 20:39:02 +0900
KUROSAWA Takahiro <kurosawa@valinux.co.jp> wrote:

> On Tue, 27 Sep 2005 01:37:51 -0700
> Paul Jackson <pj@sgi.com> wrote:
> 
> > The above reminds me of a bug fix that you provided in the previous
> > patch set, for the case *ppos >= eof.  I wonder if we have duplicated
> > code here.
> Ah, yes, we need to fix the bug in the cpuset code introduced by me...

I fixed the bug.  Sorry for my previous incomplete patch.
The following patch is against linux-2.6.14-rc2.

Signed-off-by: KUROSAWA Takahiro <kurosawa@valinux.co.jp>

--- from-0001/kernel/cpuset.c
+++ to-work/kernel/cpuset.c	2005-09-28 17:42:00.759401736 +0900
@@ -969,7 +969,7 @@ static ssize_t cpuset_common_file_read(s
 	ssize_t retval = 0;
 	char *s;
 	char *start;
-	size_t n;
+	ssize_t n;
 
 	if (!(page = (char *)__get_free_page(GFP_KERNEL)))
 		return -ENOMEM;
@@ -999,12 +999,13 @@ static ssize_t cpuset_common_file_read(s
 	*s++ = '\n';
 	*s = '\0';
 
-	/* Do nothing if *ppos is at the eof or beyond the eof. */
-	if (s - page <= *ppos)
-		return 0;
-
 	start = page + *ppos;
 	n = s - start;
+
+	/* Do nothing if *ppos is at the eof or beyond the eof. */
+	if (n <= 0)
+		goto out;
+
 	retval = n - copy_to_user(buf, start, min(n, nbytes));
 	*ppos += retval;
 out:
-
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