linux-kernel - Re: [PATCH] net: mvpp2: Fix error checking

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Message-ID: <ZGU1uVuP7nJvigtr@corigine.com>
Date:   Wed, 17 May 2023 22:14:49 +0200
From:   Simon Horman <simon.horman@...igine.com>
To:     Yeqi Fu <asuk4.q@...il.com>
Cc:     mw@...ihalf.com, linux@...linux.org.uk, davem@...emloft.net,
        edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Ivan Orlov <ivan.orlov0322@...il.com>
Subject: Re: [PATCH] net: mvpp2: Fix error checking

On Thu, May 18, 2023 at 03:08:11AM +0800, Yeqi Fu wrote:
> The function debugfs_create_dir returns ERR_PTR if an error occurs,
> and the appropriate way to verify for errors is to use the inline
> function IS_ERR. The patch will substitute the null-comparison with
> IS_ERR.

The comment above debugfs_create_dir includes the following text.

 * NOTE: it's expected that most callers should _ignore_ the errors returned
 * by this function. Other debugfs functions handle the fact that the "dentry"
 * passed to them could be an error and they don't crash in that case.
 * Drivers should generally work fine even if debugfs fails to init anyway.

And I notice that in this same file there are calls to debugfs_create_dir()
where that advice is followed: the return value is ignored.

So I think the correct approach here is to simply remove the error
checking.

And, to answer my own question while reviewing this. I don't think
Fixes tags are warranted, as debugfs_create_dir() is not expected
to return errors, so there shouldn't be a but in practice. At least
that is my reasoning.

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