linux-kernel - [PATCH] afs: Use struct

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Message-ID: <20190108213059.GA10112@embeddedor>
Date:   Tue, 8 Jan 2019 15:30:59 -0600
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     David Howells <dhowells@...hat.com>
Cc:     linux-afs@...ts.infradead.org, linux-kernel@...r.kernel.org,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Subject: [PATCH] afs: Use struct_size() in kzalloc()

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>
---
 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;
 
-- 
2.20.1