Patchwork dmaengine: tegra-apb: Use struct_size() in devm_kzalloc()

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Submitter Gustavo A. R. Silva
Date Jan. 4, 2019, 9:16 p.m.
Message ID <20190104211612.GA14300@embeddedor>
Download mbox | patch
Permalink /patch/693217/
State New
Headers show

Comments

Gustavo A. R. Silva - Jan. 4, 2019, 9:16 p.m.
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 = devm_kzalloc(dev, 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 = devm_kzalloc(dev, struct_size(instance, entry, count), GFP_KERNEL);

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 drivers/dma/tegra20-apb-dma.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
Vinod Koul - Jan. 7, 2019, 12:40 p.m.
On 04-01-19, 15:16, Gustavo A. R. Silva wrote:
> 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 = devm_kzalloc(dev, 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 = devm_kzalloc(dev, struct_size(instance, entry, count), GFP_KERNEL);
> 
> This code was detected with the help of Coccinelle.

Applied, thanks

Patch

diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
index 9a558e30c461..697f316055cf 100644
--- a/drivers/dma/tegra20-apb-dma.c
+++ b/drivers/dma/tegra20-apb-dma.c
@@ -1319,8 +1319,9 @@  static int tegra_dma_probe(struct platform_device *pdev)
 		return -ENODEV;
 	}
 
-	tdma = devm_kzalloc(&pdev->dev, sizeof(*tdma) + cdata->nr_channels *
-			sizeof(struct tegra_dma_channel), GFP_KERNEL);
+	tdma = devm_kzalloc(&pdev->dev,
+			    struct_size(tdma, channels, cdata->nr_channels),
+			    GFP_KERNEL);
 	if (!tdma)
 		return -ENOMEM;