linux-kernel - Re: [PATCH 1/2] dmaengine: Cleanups for the slave <-> channel symlink support

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Message-ID: <fef9eeac-f088-61e8-eecc-a106a6f09224@ti.com>
Date:   Fri, 31 Jan 2020 09:14:22 +0200
From:   Peter Ujfalusi <peter.ujfalusi@...com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
CC:     Vinod <vkoul@...nel.org>, <dmaengine@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Dan Williams <dan.j.williams@...el.com>
Subject: Re: [PATCH 1/2] dmaengine: Cleanups for the slave <-> channel symlink
 support

Hi Geert,

On 30/01/2020 17.20, Geert Uytterhoeven wrote:
> Hi Peter,
> 
> On Thu, Jan 30, 2020 at 12:41 PM Peter Ujfalusi <peter.ujfalusi@...com> wrote:
>> No need to use goto to jump over the
>> return chan ? chan : ERR_PTR(-EPROBE_DEFER);
>> We can just revert the check and return right there.
>>
>> Do not fail the channel request if the chan->name allocation fails, but
>> print a warning about it.
>>
>> Change the dev_err to dev_warn if sysfs_create_link() fails as it is not
>> fatal.
>>
>> Only attempt to remove the DMA_SLAVE_NAME symlink if it is created - or it
>> was attempted to be created.
>>
>> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@...com>
> 
> Thanks for your patch!
> 
>> --- a/drivers/dma/dmaengine.c
>> +++ b/drivers/dma/dmaengine.c
>> @@ -756,22 +756,24 @@ struct dma_chan *dma_request_chan(struct device *dev, const char *name)
>>         }
>>         mutex_unlock(&dma_list_mutex);
>>
>> -       if (!IS_ERR_OR_NULL(chan))
>> -               goto found;
>> -
>> -       return chan ? chan : ERR_PTR(-EPROBE_DEFER);
>> +       if (IS_ERR_OR_NULL(chan))
>> +               return chan ? chan : ERR_PTR(-EPROBE_DEFER);
>>
>>  found:
>> -       chan->slave = dev;
>>         chan->name = kasprintf(GFP_KERNEL, "dma:%s", name);
>> -       if (!chan->name)
>> -               return ERR_PTR(-ENOMEM);
>> +       if (!chan->name) {
>> +               dev_warn(dev,
>> +                        "Cannot allocate memory for slave symlink name\n");
> 
> No need to print a message, as the memory allocator core will have
> screamed already.

Right, I tend to forget this ;)

> 
>> +               return chan;
>> +       }
>> +       chan->slave = dev;
>>
>>         if (sysfs_create_link(&chan->dev->device.kobj, &dev->kobj,
>>                               DMA_SLAVE_NAME))
>> -               dev_err(dev, "Cannot create DMA %s symlink\n", DMA_SLAVE_NAME);
>> +               dev_warn(dev, "Cannot create DMA %s symlink\n", DMA_SLAVE_NAME);
>>         if (sysfs_create_link(&dev->kobj, &chan->dev->device.kobj, chan->name))
>> -               dev_err(dev, "Cannot create DMA %s symlink\n", chan->name);
>> +               dev_warn(dev, "Cannot create DMA %s symlink\n", chan->name);
>> +
>>         return chan;
>>  }
>>  EXPORT_SYMBOL_GPL(dma_request_chan);
> 
> With the above fixed:
> Reviewed-by: Geert Uytterhoeven <geert+renesas@...der.be>

Thanks,
- Péter

> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 

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