linux-kernel - Re: [PATCH -next] drm/imagination: Use memdup

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Message-ID: <b493404f-9f7e-6f90-893e-84ff2bcb0170@huawei.com>
Date: Mon, 2 Sep 2024 10:17:20 +0800
From: Jinjie Ruan <ruanjinjie@...wei.com>
To: Christophe JAILLET <christophe.jaillet@...adoo.fr>,
	<frank.binns@...tec.com>, <matt.coster@...tec.com>,
	<maarten.lankhorst@...ux.intel.com>, <mripard@...nel.org>,
	<tzimmermann@...e.de>, <airlied@...il.com>, <daniel@...ll.ch>,
	<dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH -next] drm/imagination: Use memdup_user() helper



On 2024/8/31 18:48, Christophe JAILLET wrote:
> Le 31/08/2024 à 12:30, Jinjie Ruan a écrit :
>> Switching to memdup_user(), which combines kmalloc() and
>> copy_from_user(),
>> and it can simplfy code.
>>
>> Signed-off-by: Jinjie Ruan <ruanjinjie@...wei.com>
>> ---
>>   drivers/gpu/drm/imagination/pvr_context.c | 22 +++++++---------------
>>   1 file changed, 7 insertions(+), 15 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/imagination/pvr_context.c
>> b/drivers/gpu/drm/imagination/pvr_context.c
>> index eded5e955cc0..e75fd50a4d9f 100644
>> --- a/drivers/gpu/drm/imagination/pvr_context.c
>> +++ b/drivers/gpu/drm/imagination/pvr_context.c
>> @@ -69,27 +69,19 @@ process_static_context_state(struct pvr_device
>> *pvr_dev, const struct pvr_stream
>>       void *stream;
>>       int err;
>>   -    stream = kzalloc(stream_size, GFP_KERNEL);
>> -    if (!stream)
>> -        return -ENOMEM;
>> -
>> -    if (copy_from_user(stream, u64_to_user_ptr(stream_user_ptr),
>> stream_size)) {
>> -        err = -EFAULT;
>> -        goto err_free;
>> -    }
>> +    stream = memdup_user(u64_to_user_ptr(stream_user_ptr), stream_size);
>> +    if (IS_ERR(stream))
>> +        return PTR_ERR(stream);
>>         err = pvr_stream_process(pvr_dev, cmd_defs, stream,
>> stream_size, dest);
>> -    if (err)
>> -        goto err_free;
>> +    if (err) {
>> +        kfree(stream);
>> +        return err;
>> +    }
>>         kfree(stream);
>>         return 0;
>> -
>> -err_free:
>> -    kfree(stream);
>> -
>> -    return err;
>>   }
> 
> It could also be:
>      err = pvr_stream_process(...);
> 
>      kfree(stream);
> 
>      return err;
> 
> as you did for drivers/gpu/drm/imagination/pvr_job.c.

You are right! that will be more clean.

> 
> CJ
> 
>>     static int init_render_fw_objs(struct pvr_context *ctx,
> 
>