linux-kernel - Re: [PATCH 4/6] dma: pxa_dma: no need to check return value of debugfs

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Date:   Tue, 13 Aug 2019 23:21:04 +0200
From:   Robert Jarzmik <robert.jarzmik@...e.fr>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     dan.j.williams@...el.com, vkoul@...nel.org,
        Daniel Mack <daniel@...que.org>,
        Haojian Zhuang <haojian.zhuang@...il.com>,
        linux-arm-kernel@...ts.infradead.org, dmaengine@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/6] dma: pxa_dma: no need to check return value of debugfs_create functions

Greg Kroah-Hartman <gregkh@...uxfoundation.org> writes:

> On Sat, Aug 10, 2019 at 09:27:26PM +0200, Robert Jarzmik wrote:
>> Greg Kroah-Hartman <gregkh@...uxfoundation.org> writes:
>> 
>> This is not strictly equivalent.
>> Imagine that the debugfs_create_dir() fails and returns NULL :
> How can that happen?
Well in v5.0-rc1 that could happen ... unfortunately that's also the code I
checked ...

>>  - in the former case, neither "state", "descriptors" nor "requesters" would be
>>    created
>>  - in the new code, "state", "descriptors" nor "requesters" will be created in
>>    the debugfs root directory
>
> I agree, but debugfs_create_dir() does not return a NULL on an error
> since many kernel releases.  Neither can debugfs_create_file() so really
> this test is not working at all as-is :)
Ah yes, you're right, I wasn't aware of the debugfs changes ...

But checking a bit further, your original mail is 2 monthes old, and this patch
was already merged in v5.2. I probably fell in a time-space anomaly, as I
received this mail only a couple of days ago.

Have a nice day.

-- 
Robert