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From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
To: Andy Gross <andy.gross@linaro.org>,
	David Brown <david.brown@linaro.org>,
	Dan Williams <dan.j.williams@intel.com>,
	Vinod Koul <vkoul@kernel.org>
Cc: linux-arm-msm@vger.kernel.org, dmaengine@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	"Gustavo A. R. Silva" <gustavo@embeddedor.com>
Subject: dmaengine: qcom: bam_dma: use struct_size() in kzalloc()
Date: Fri, 4 Jan 2019 11:32:15 -0600	[thread overview]
Message-ID: <20190104173215.GA29029@embeddedor> (raw)

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@embeddedor.com>
---
 drivers/dma/qcom/bam_dma.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/qcom/bam_dma.c b/drivers/dma/qcom/bam_dma.c
index 1617715aa6e0..cb860cb53c27 100644
--- a/drivers/dma/qcom/bam_dma.c
+++ b/drivers/dma/qcom/bam_dma.c
@@ -636,8 +636,8 @@ static struct dma_async_tx_descriptor *bam_prep_slave_sg(struct dma_chan *chan,
 		num_alloc += DIV_ROUND_UP(sg_dma_len(sg), BAM_FIFO_SIZE);
 
 	/* allocate enough room to accomodate the number of entries */
-	async_desc = kzalloc(sizeof(*async_desc) +
-			(num_alloc * sizeof(struct bam_desc_hw)), GFP_NOWAIT);
+	async_desc = kzalloc(struct_size(async_desc, desc, num_alloc),
+			     GFP_NOWAIT);
 
 	if (!async_desc)
 		goto err_out;

WARNING: multiple messages have this Message-ID (diff)
From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
To: Andy Gross <andy.gross@linaro.org>,
	David Brown <david.brown@linaro.org>,
	Dan Williams <dan.j.williams@intel.com>,
	Vinod Koul <vkoul@kernel.org>
Cc: linux-arm-msm@vger.kernel.org, dmaengine@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	"Gustavo A. R. Silva" <gustavo@embeddedor.com>
Subject: [PATCH] dmaengine: qcom: bam_dma: use struct_size() in kzalloc()
Date: Fri, 4 Jan 2019 11:32:15 -0600	[thread overview]
Message-ID: <20190104173215.GA29029@embeddedor> (raw)

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@embeddedor.com>
---
 drivers/dma/qcom/bam_dma.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/qcom/bam_dma.c b/drivers/dma/qcom/bam_dma.c
index 1617715aa6e0..cb860cb53c27 100644
--- a/drivers/dma/qcom/bam_dma.c
+++ b/drivers/dma/qcom/bam_dma.c
@@ -636,8 +636,8 @@ static struct dma_async_tx_descriptor *bam_prep_slave_sg(struct dma_chan *chan,
 		num_alloc += DIV_ROUND_UP(sg_dma_len(sg), BAM_FIFO_SIZE);
 
 	/* allocate enough room to accomodate the number of entries */
-	async_desc = kzalloc(sizeof(*async_desc) +
-			(num_alloc * sizeof(struct bam_desc_hw)), GFP_NOWAIT);
+	async_desc = kzalloc(struct_size(async_desc, desc, num_alloc),
+			     GFP_NOWAIT);
 
 	if (!async_desc)
 		goto err_out;
-- 
2.20.1

             reply	other threads:[~2019-01-04 17:32 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-04 17:32 Gustavo A. R. Silva [this message]
2019-01-04 17:32 ` [PATCH] dmaengine: qcom: bam_dma: use struct_size() in kzalloc() Gustavo A. R. Silva
2019-01-07 12:40 Vinod Koul
2019-01-07 12:40 ` [PATCH] " Vinod Koul

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