linux-kernel - Re: [PATCH] drivers: qcom: rpmh: use struct

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Message-ID: <c8fc7bfc-122a-14a8-8916-0e020c485c2d@embeddedor.com>
Date:   Tue, 29 Jan 2019 00:57:02 -0600
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     Amit Kucheria <amit.kucheria@...durent.com>
Cc:     Andy Gross <andy.gross@...aro.org>,
        David Brown <david.brown@...aro.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drivers: qcom: rpmh: use struct_size() in kzalloc()



On 1/28/19 11:26 PM, Amit Kucheria wrote:
> On Mon, Dec 24, 2018 at 11:52 AM Gustavo A. R. Silva
> <gustavo@...eddedor.com> 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 = 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@...eddedor.com>
> 
> Reviewed-by: Amit Kucheria <amit.kucheria@...aro.org>
> 

Thanks, Amit.

--
Gustavo

>> ---
>>  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
>>