linux-kernel - Re: [RFC][PATCH 1/5 v2] dma-buf: Add dma-buf heaps framework

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Message-ID: <525c65f4-7d73-bc77-5086-4db70e6e54f2@ti.com>
Date:   Fri, 15 Mar 2019 15:24:44 -0500
From:   "Andrew F. Davis" <afd@...com>
To:     Christoph Hellwig <hch@...radead.org>,
        John Stultz <john.stultz@...aro.org>
CC:     lkml <linux-kernel@...r.kernel.org>,
        Laura Abbott <labbott@...hat.com>,
        Benjamin Gaignard <benjamin.gaignard@...aro.org>,
        Greg KH <gregkh@...uxfoundation.org>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Liam Mark <lmark@...eaurora.org>,
        Brian Starkey <Brian.Starkey@....com>,
        Chenbo Feng <fengc@...gle.com>,
        Alistair Strachan <astrachan@...gle.com>,
        <dri-devel@...ts.freedesktop.org>
Subject: Re: [RFC][PATCH 1/5 v2] dma-buf: Add dma-buf heaps framework

On 3/15/19 3:54 AM, Christoph Hellwig wrote:
>> +static int dma_heap_release(struct inode *inode, struct file *filp)
>> +{
>> +	filp->private_data = NULL;
>> +
>> +	return 0;
>> +}
> 
> No point in clearing ->private_data, the file is about to be freed.
> 

This was leftover from when release had some memory to free, will remove.

>> +
>> +static long dma_heap_ioctl(struct file *filp, unsigned int cmd,
>> +			   unsigned long arg)
> 
> Pleae don't use the weird legacy filp naming, file is a perfectly
> valid and readable default name for struct file pointers.
> 

Thanks for info, I saw both used and this was used where I found the
prototype so I used it too, will fix.

>> +{
>> +	switch (cmd) {
>> +	case DMA_HEAP_IOC_ALLOC:
>> +	{
>> +		struct dma_heap_allocation_data heap_allocation;
>> +		struct dma_heap *heap = filp->private_data;
>> +		int fd;
> 
> Please split each ioctl into a separate function from the very start,
> otherwise this will grow into a spaghetty mess sooner than you can
> see cheese.
> 

Good idea, will fix.

>> +	dev_ret = device_create(dma_heap_class,
>> +				NULL,
>> +				heap->heap_devt,
>> +				NULL,
>> +				heap->name);
> 
> No need this weird argument alignment.
> 

I kinda like it this way, if everything cant fit on one line then
everything gets its own line, seems more consistent. If there is strong
objection I can fix.