linux-kernel - [PATCH] mtd: lpddr: Use struct

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Date:   Tue, 8 Jan 2019 15:09:46 -0600
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Boris Brezillon <bbrezillon@...nel.org>,
        Marek Vasut <marek.vasut@...il.com>,
        Richard Weinberger <richard@....at>
Cc:     linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Subject: [PATCH] mtd: lpddr: 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>
---
 drivers/mtd/lpddr/qinfo_probe.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/lpddr/qinfo_probe.c b/drivers/mtd/lpddr/qinfo_probe.c
index 69f2112340b1..175bdc3b72f4 100644
--- a/drivers/mtd/lpddr/qinfo_probe.c
+++ b/drivers/mtd/lpddr/qinfo_probe.c
@@ -181,8 +181,8 @@ static struct lpddr_private *lpddr_probe_chip(struct map_info *map)
 	lpddr.numchips = 1;
 
 	numvirtchips = lpddr.numchips * lpddr.qinfo->HWPartsNum;
-	retlpddr = kzalloc(sizeof(struct lpddr_private) +
-			numvirtchips * sizeof(struct flchip), GFP_KERNEL);
+	retlpddr = kzalloc(struct_size(retlpddr, chips, numvirtchips),
+			   GFP_KERNEL);
 	if (!retlpddr)
 		return NULL;
 
-- 
2.20.1