netdev - Re: [PATCH net-next v1] sunrpc: Use ERR

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Message-ID: <92e3c3f9-3ee7-43d4-a4af-70ca87adacb2@intel.com>
Date: Fri, 30 Aug 2024 15:39:24 +0200
From: Alexander Lobakin <aleksander.lobakin@...el.com>
To: Trond Myklebust <trondmy@...merspace.com>
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Subject: Re: [PATCH net-next v1] sunrpc: Use ERR_CAST() to return

From: Trond Myklebust <trondmy@...merspace.com>
Date: Fri, 30 Aug 2024 02:08:09 +0000

> On Fri, 2024-08-30 at 09:42 +0800, Yan Zhen wrote:
>> Using ERR_CAST() is more reasonable and safer, When it is necessary
>> to convert the type of an error pointer and return it.
> 
> static inline void * __must_check ERR_CAST(__force const void *ptr)
> {
>         /* cast away the const */
>         return (void *) ptr;
> }
> 
> That function is literally just doing an implicit cast from whatever
> pointer type it is now, to a 'const void *' and then to a 'void *',
> which then gets implicitly cast to whatever type the caller is
> expecting. Exactly how is that "safer" than the current explicit cast?

I think we might want to reimplement ERR_CAST() using _Generic() to not
cast away const when the argument itself is const.

> 
> While it is great that ERR_CAST() exists, and I agree that it should be
> preferred in newer code for the (sole (!)) reason that it documents
> that we expect this to be an error, I see no reason why it is
> imperative to apply that change to existing code. Particularly not as a
> standalone patch.
> 
> So NACK for now.

Thanks,
Olek