From: Gustavo A. R. Silva <gustavo@embeddedor.com>
Date: Thu, 11 Apr 2019 23:43:06 +0000 (-0500)
Subject: rhashtable: use struct_size() in kvzalloc()
X-Git-Tag: for-linus-20190516~56^2~180
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=c252aa3e8ed3ac54060b1838f6a47f29799a133d;p=linux-block.git

rhashtable: use struct_size() in kvzalloc()

One of the more common cases of allocation size calculations is finding
the size of a structure that has a zero-sized array at the end, along with
memory for some number of elements for that array.  For example:

struct foo {
    int stuff;
    struct boo entry[];
};

size = sizeof(struct foo) + count * sizeof(struct boo);
instance = kvzalloc(size, GFP_KERNEL);

Instead of leaving these open-coded and prone to type mistakes, we can
now use the new struct_size() helper:

instance = kvzalloc(struct_size(instance, entry, count), GFP_KERNEL);

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index a8583af43b59..9c84f5cef69c 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -175,8 +175,7 @@ static struct bucket_table *bucket_table_alloc(struct rhashtable *ht,
 	int i;
 	static struct lock_class_key __key;
 
-	size = sizeof(*tbl) + nbuckets * sizeof(tbl->buckets[0]);
-	tbl = kvzalloc(size, gfp);
+	tbl = kvzalloc(struct_size(tbl, buckets, nbuckets), gfp);
 
 	size = nbuckets;