linux-kernel - [PATCH 3.16 052/204] IB/mlx5: Fix the size parameter to find_first

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Message-ID: <lsq.1514480744.737182216@decadent.org.uk>
Date:   Thu, 28 Dec 2017 17:05:44 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Leon Romanovsky" <leonro@...lanox.com>,
        "Doug Ledford" <dledford@...hat.com>,
        "Christophe Jaillet" <christophe.jaillet@...adoo.fr>,
        "Majd Dibbiny" <majd@...lanox.com>
Subject: [PATCH 3.16 052/204] IB/mlx5: Fix the size parameter to
 find_first_bit

3.16.52-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Christophe Jaillet <christophe.jaillet@...adoo.fr>

commit fffd68734dc685e208e86d8c5f6522cd695a8d60 upstream.

The 2nd parameter of 'find_first_bit' is the number of bits to search.
In this case, we are passing 'sizeof(tmp)' which is likely to be 4 or 8
because 'tmp' is an 'unsigned long'.

It is likely that the number of bits of 'tmp' was expected here. So use
BITS_PER_LONG instead.

It has been spotted by the following coccinelle script:
@@
expression ret, x;

@@
*  ret = \(find_first_bit \| find_first_zero_bit\) (x, sizeof(...));

Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
Acked-by: Majd Dibbiny <majd@...lanox.com>
Acked-by: Leon Romanovsky <leonro@...lanox.com>
Signed-off-by: Doug Ledford <dledford@...hat.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/infiniband/hw/mlx5/mem.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/infiniband/hw/mlx5/mem.c
+++ b/drivers/infiniband/hw/mlx5/mem.c
@@ -58,7 +58,7 @@ void mlx5_ib_cont_pages(struct ib_umem *
 
 	addr = addr >> PAGE_SHIFT;
 	tmp = (unsigned long)addr;
-	m = find_first_bit(&tmp, sizeof(tmp));
+	m = find_first_bit(&tmp, BITS_PER_LONG);
 	skip = 1 << m;
 	mask = skip - 1;
 	i = 0;
@@ -68,7 +68,7 @@ void mlx5_ib_cont_pages(struct ib_umem *
 		for (k = 0; k < len; k++) {
 			if (!(i & mask)) {
 				tmp = (unsigned long)pfn;
-				m = min_t(unsigned long, m, find_first_bit(&tmp, sizeof(tmp)));
+				m = min_t(unsigned long, m, find_first_bit(&tmp, BITS_PER_LONG));
 				skip = 1 << m;
 				mask = skip - 1;
 				base = pfn;
@@ -76,7 +76,7 @@ void mlx5_ib_cont_pages(struct ib_umem *
 			} else {
 				if (base + p != pfn) {
 					tmp = (unsigned long)p;
-					m = find_first_bit(&tmp, sizeof(tmp));
+					m = find_first_bit(&tmp, BITS_PER_LONG);
 					skip = 1 << m;
 					mask = skip - 1;
 					base = pfn;