linux-kernel - [PATCH 1/6] afs: Use struct

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Message-ID: <154773885685.24105.3699803861773624915.stgit@warthog.procyon.org.uk>
Date:   Thu, 17 Jan 2019 15:27:36 +0000
From:   David Howells <dhowells@...hat.com>
To:     torvalds@...ux-foundation.org
Cc:     "Gustavo A. R. Silva" <gustavo@...eddedor.com>,
        dhowells@...hat.com, linux-afs@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 1/6] afs: Use struct_size() in kzalloc()

From: Gustavo A. R. Silva <gustavo@...eddedor.com>

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;
    void *entry[];
};

instance = kzalloc(sizeof(struct foo) + sizeof(void *) * count, GFP_KERNEL);

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

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

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>
Signed-off-by: David Howells <dhowells@...hat.com>
---

 fs/afs/server_list.c |    4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/fs/afs/server_list.c b/fs/afs/server_list.c
index 95d0761cdb34..155dc14caef9 100644
--- a/fs/afs/server_list.c
+++ b/fs/afs/server_list.c
@@ -42,9 +42,7 @@ struct afs_server_list *afs_alloc_server_list(struct afs_cell *cell,
 		if (vldb->fs_mask[i] & type_mask)
 			nr_servers++;
 
-	slist = kzalloc(sizeof(struct afs_server_list) +
-			sizeof(struct afs_server_entry) * nr_servers,
-			GFP_KERNEL);
+	slist = kzalloc(struct_size(slist, servers, nr_servers), GFP_KERNEL);
 	if (!slist)
 		goto error;