linux-kernel - [PATCH] dmaengine: timb_dma: Use struct

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Message-ID: <20190108155852.GA17782@embeddedor>
Date:   Tue, 8 Jan 2019 09:58:52 -0600
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     Dan Williams <dan.j.williams@...el.com>,
        Vinod Koul <vkoul@...nel.org>
Cc:     dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Subject: [PATCH] dmaengine: timb_dma: 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/dma/timb_dma.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/timb_dma.c b/drivers/dma/timb_dma.c
index fc0f9c8766a8..afbb1c95b721 100644
--- a/drivers/dma/timb_dma.c
+++ b/drivers/dma/timb_dma.c
@@ -643,8 +643,8 @@ static int td_probe(struct platform_device *pdev)
 		DRIVER_NAME))
 		return -EBUSY;
 
-	td  = kzalloc(sizeof(struct timb_dma) +
-		sizeof(struct timb_dma_chan) * pdata->nr_channels, GFP_KERNEL);
+	td  = kzalloc(struct_size(td, channels, pdata->nr_channels),
+		      GFP_KERNEL);
 	if (!td) {
 		err = -ENOMEM;
 		goto err_release_region;
-- 
2.20.1