netdev - Re: [PATCH net 4/4] net: Comment copy_from_sockptr() explaining its behaviour

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Message-ID: <f8d09aa1-b83d-4eaa-8202-b8cb6979d85f@davidwei.uk>
Date: Thu, 14 Nov 2024 18:43:37 -0800
From: David Wei <dw@...idwei.uk>
To: Michal Luczaj <mhal@...x.co>, Marcel Holtmann <marcel@...tmann.org>,
 Johan Hedberg <johan.hedberg@...il.com>,
 Luiz Augusto von Dentz <luiz.dentz@...il.com>,
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>,
 David Howells <dhowells@...hat.com>, Marc Dionne <marc.dionne@...istor.com>
Cc: Luiz Augusto von Dentz <luiz.von.dentz@...el.com>,
 linux-bluetooth@...r.kernel.org, netdev@...r.kernel.org,
 linux-afs@...ts.infradead.org, Jakub Kicinski <kuba@...nel.org>,
 David Wei <dw@...idwei.uk>
Subject: Re: [PATCH net 4/4] net: Comment copy_from_sockptr() explaining its
 behaviour

On 2024-11-14 15:27, Michal Luczaj wrote:
> copy_from_sockptr() has a history of misuse. Add a comment explaining that
> the function follows API of copy_from_user(), i.e. returns 0 for success,
> or number of bytes not copied on error.
> 
> Signed-off-by: Michal Luczaj <mhal@...x.co>
> ---
>  include/linux/sockptr.h | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/include/linux/sockptr.h b/include/linux/sockptr.h
> index 195debe2b1dbc5abf768aa806eb6c73b99421e27..3e6c8e9d67aef66e8ac5a4e474c278ac08244163 100644
> --- a/include/linux/sockptr.h
> +++ b/include/linux/sockptr.h
> @@ -53,6 +53,8 @@ static inline int copy_from_sockptr_offset(void *dst, sockptr_t src,
>  /* Deprecated.
>   * This is unsafe, unless caller checked user provided optlen.
>   * Prefer copy_safe_from_sockptr() instead.
> + *
> + * Returns 0 for success, or number of bytes not copied on error.
>   */
>  static inline int copy_from_sockptr(void *dst, sockptr_t src, size_t size)
>  {
> 

In addition to this, please update the docs for copy_safe_from_sockptr()
that calls into copy_from_sockptr() which also contains the
misunderstanding of what copy_from_sockptr() returns.