linux-kernel - [PATCH] powerpc/ps3: Use struct

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Message-ID: <20190108210010.GA980@embeddedor>
Date:   Tue, 8 Jan 2019 15:00:10 -0600
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     Geoff Levand <geoff@...radead.org>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Subject: [PATCH] powerpc/ps3: 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>
---
 arch/powerpc/platforms/ps3/device-init.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/arch/powerpc/platforms/ps3/device-init.c b/arch/powerpc/platforms/ps3/device-init.c
index e7075aaff1bb..59587b75493d 100644
--- a/arch/powerpc/platforms/ps3/device-init.c
+++ b/arch/powerpc/platforms/ps3/device-init.c
@@ -354,9 +354,7 @@ static int ps3_setup_storage_dev(const struct ps3_repository_device *repo,
 		 repo->dev_index, repo->dev_type, port, blk_size, num_blocks,
 		 num_regions);
 
-	p = kzalloc(sizeof(struct ps3_storage_device) +
-		    num_regions * sizeof(struct ps3_storage_region),
-		    GFP_KERNEL);
+	p = kzalloc(struct_size(p, regions, num_regions), GFP_KERNEL);
 	if (!p) {
 		result = -ENOMEM;
 		goto fail_malloc;
-- 
2.20.1