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Date:   Mon, 24 Dec 2018 00:22:35 -0600
From:   "Gustavo A. R. Silva" <gustavo@embeddedor.com>
To:     Andy Gross <andy.gross@linaro.org>,
        David Brown <david.brown@linaro.org>
Cc:     linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
        "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Subject: [PATCH] drivers: qcom: rpmh: use struct_size() in kzalloc()
Message-ID: <20181224062235.GA27815@embeddedor.com>
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User-Agent: Mutt/1.9.4 (2018-02-28)
Sender: linux-kernel-owner@vger.kernel.org
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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 issue was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 drivers/soc/qcom/rpmh.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/soc/qcom/rpmh.c b/drivers/soc/qcom/rpmh.c
index c7beb6841289..12c057a0b325 100644
--- a/drivers/soc/qcom/rpmh.c
+++ b/drivers/soc/qcom/rpmh.c
@@ -362,8 +362,7 @@ int rpmh_write_batch(const struct device *dev, enum rpmh_state state,
 	if (!count)
 		return -EINVAL;
 
-	req = kzalloc(sizeof(*req) + count * sizeof(req->rpm_msgs[0]),
-		      GFP_ATOMIC);
+	req = kzalloc(struct_size(req, rpm_msgs, count), GFP_ATOMIC);
 	if (!req)
 		return -ENOMEM;
 	req->count = count;
-- 
2.17.0