Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Cc:     mtk.manpages@gmail.com, adrian@lisas.de, akpm@linux-foundation.org,
        arnd@arndb.de, avagin@gmail.com, christian.brauner@ubuntu.com,
        dhowells@redhat.com, fweimer@redhat.com, jannh@google.com,
        keescook@chromium.org, linux-api@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-man@vger.kernel.org,
        mingo@elte.hu, oleg@redhat.com, xemul@virtuozzo.com
Subject: Re: [PATCH 3/3] clone.2: Use pid_t for clone3() {child,parent}_tid
To:     Christian Brauner <christian@brauner.io>
References: <20191116114114.7066-1-christian@brauner.io>
 <20191116114114.7066-3-christian@brauner.io>
From:   "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>
Message-ID: <c70c0ddf-1cd2-9d33-c2f6-95c8faa546cf@gmail.com>
Date:   Sun, 17 Nov 2019 19:02:04 +0100
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101
 Thunderbird/60.6.1
MIME-Version: 1.0
In-Reply-To: <20191116114114.7066-3-christian@brauner.io>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 11/16/19 12:41 PM, Christian Brauner wrote:
> From: Christian Brauner <christian.brauner@ubuntu.com>
>
> Advertise to userspace that they should use proper pid_t types for
> arguments returning a pid.
> The kernel-internal struct kernel_clone_args currently uses int as type
> and since POSIX mandates that pid_t is a signed integer type and glibc
> and friends use int this is not an issue. After the merge window for
> v5.5 closes we can switch struct kernel_clone_args over to using pid_t
> as well without any danger in regressing current userspace.
> Also note, that the new set tid feature which will be merged for v5.5
> uses pid_t types as well.

Thanks taking a further pass throuh this page, Christian, 

Patch applied.

Cheers,

Michael

 
> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
> ---
>  man2/clone.2 | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/man2/clone.2 b/man2/clone.2
> index faff2ada6..bf2d7c731 100644
> --- a/man2/clone.2
> +++ b/man2/clone.2
> @@ -183,9 +183,9 @@ is a structure of the following form:
>  struct clone_args {
>      u64 flags;        /* Flags bit mask */
>      u64 pidfd;        /* Where to store PID file descriptor
> -                         (\fIint *\fP) */
> +                         (\fIpid_t *\fP) */
>      u64 child_tid;    /* Where to store child TID,
> -                         in child's memory (\fIint *\fP) */
> +                         in child's memory (\fIpid_t *\fP) */
>      u64 parent_tid;   /* Where to store child TID,
>                           in parent's memory (\fIint *\fP) */
>      u64 exit_signal;  /* Signal to deliver to parent on
> 


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/