linux-kernel - Re: [PATCH] net: make getname() functions return length rather than use int* parameter

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Date:   Mon, 12 Feb 2018 18:59:06 +0100
From:   Denys Vlasenko <dvlasenk@...hat.com>
To:     David Miller <davem@...emloft.net>
Cc:     linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        linux-bluetooth@...r.kernel.org,
        linux-decnet-user@...ts.sourceforge.net,
        linux-wireless@...r.kernel.org, linux-rdma@...r.kernel.org,
        linux-sctp@...r.kernel.org, linux-nfs@...r.kernel.org,
        linux-x25@...r.kernel.org
Subject: Re: [PATCH] net: make getname() functions return length rather than
 use int* parameter

On 02/12/2018 06:47 PM, David Miller wrote:
> From: Denys Vlasenko <dvlasenk@...hat.com>
> Date: Mon, 12 Feb 2018 15:15:18 +0100
> 
>> Before:
>> All these functions either return a negative error indicator,
>> or store length of sockaddr into "int *socklen" parameter
>> and return zero on success.
>>
>> "int *socklen" parameter is awkward. For example, if caller does not
>> care, it still needs to provide on-stack storage for the value
>> it does not need.
>>
>> None of the many FOO_getname() functions of various protocols
>> ever used old value of *socklen. They always just overwrite it.
>>
>> This change drops this parameter, and makes all these functions, on success,
>> return length of sockaddr. It's always >= 0 and can be differentiated
>> from an error.
>>
>> Tests in callers are changed from "if (err)" to "if (err < 0)", where needed.
>>
>> rpc_sockname() lost "int buflen" parameter, since its only use was
>> to be passed to kernel_getsockname() as &buflen and subsequently
>> not used in any way.
>>
>> Userspace API is not changed.
>>
>>      text    data     bss      dec     hex filename
>> 30108430 2633624  873672 33615726 200ef6e vmlinux.before.o
>> 30108109 2633612  873672 33615393 200ee21 vmlinux.o
>>
>> Signed-off-by: Denys Vlasenko <dvlasenk@...hat.com>
> 
> Please do an allmodconfig build, there are still some conversions you
> missed:
> 
> security/tomoyo/network.c: In function ‘tomoyo_socket_listen_permission’:
> security/tomoyo/network.c:658:19: warning: passing argument 3 of ‘sock->ops->getname’ makes integer from pointer without a cast [-Wint-conversion]
>              &addr, &addr_len, 0);
>                     ^
> security/tomoyo/network.c:658:19: note: expected ‘int’ but argument is of type ‘int *’
> security/tomoyo/network.c:657:21: error: too many arguments to function ‘sock->ops->getname’
>     const int error = sock->ops->getname(sock, (struct sockaddr *)
>                       ^~~~
> fs/dlm/lowcomms.c: In function ‘lowcomms_error_report’:
> fs/dlm/lowcomms.c:495:6: error: too many arguments to function ‘kernel_getpeername’
>        kernel_getpeername(con->sock, (struct sockaddr *)&saddr, &buflen)) {
>        ^~~~~~~~~~~~~~~~~~
> fs/dlm/lowcomms.c: In function ‘tcp_accept_from_sock’:
> fs/dlm/lowcomms.c:761:7: warning: passing argument 3 of ‘newsock->ops->getname’ makes integer from pointer without a cast [-Wint-conversion]
>         &len, 2)) {
>         ^
> fs/dlm/lowcomms.c:761:7: note: expected ‘int’ but argument is of type ‘int *’
> fs/dlm/lowcomms.c:760:6: error: too many arguments to function ‘newsock->ops->getname’
>    if (newsock->ops->getname(newsock, (struct sockaddr *)&peeraddr,
>        ^~~~~~~

Sorry. Will send updated patch.