linux-kernel - [PATCH 1/2] staging: lustre: lprocfs: Use kstrtouint_from

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Date:   Thu,  4 May 2017 12:13:38 -0400
From:   Mathias Rav <mathiasrav@...il.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        devel@...verdev.osuosl.org, Oleg Drokin <oleg.drokin@...el.com>,
        Andreas Dilger <andreas.dilger@...el.com>,
        James Simmons <jsimmons@...radead.org>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Lustre Development List <lustre-devel@...ts.lustre.org>,
        Mathias Rav <mathiasrav@...il.com>
Subject: [PATCH 1/2] staging: lustre: lprocfs: Use kstrtouint_from_user

Prefer kstrtouint_from_user to copy_from_user+simple_strtoul.

The helper function lprocfs_wr_uint() is only used to implement
"dump_granted_max" in debugfs.

Note the slight change in semantics: The previous implementation using
simple_strtoul allows garbage after the number, whereas kstrtox only allows
a trailing line break. The previous implementation allowed a write of zero
bytes whereas kstrtox will return -EINVAL. Since this only affects a single
debugfs endpoint, this should be a permissible slight change of semantics
in exchange for 18 fewer lines of code.

Signed-off-by: Mathias Rav <mathiasrav@...il.com>
---
 .../lustre/lustre/obdclass/lprocfs_status.c        | 22 +---------------------
 1 file changed, 1 insertion(+), 21 deletions(-)

diff --git a/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c b/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
index 1ec6e3767d81..338ce34d6514 100644
--- a/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
+++ b/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
@@ -399,27 +399,7 @@ EXPORT_SYMBOL(lprocfs_rd_uint);
 int lprocfs_wr_uint(struct file *file, const char __user *buffer,
 		    unsigned long count, void *data)
 {
-	unsigned *p = data;
-	char dummy[MAX_STRING_SIZE + 1], *end;
-	unsigned long tmp;
-
-	if (count >= sizeof(dummy))
-		return -EINVAL;
-
-	if (count == 0)
-		return 0;
-
-	if (copy_from_user(dummy, buffer, count))
-		return -EFAULT;
-
-	dummy[count] = '\0';
-
-	tmp = simple_strtoul(dummy, &end, 0);
-	if (dummy == end)
-		return -EINVAL;
-
-	*p = (unsigned int)tmp;
-	return count;
+	return kstrtouint_from_user(buffer, count, 0, (unsigned int *)data);
 }
 EXPORT_SYMBOL(lprocfs_wr_uint);
 
-- 
2.12.2