linux-kernel - Re: [PATCH 05/32] timerfd/timens: Take into account ns clock offsets

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Message-ID: <20190206085203.GB25251@uranus>
Date:   Wed, 6 Feb 2019 11:52:03 +0300
From:   Cyrill Gorcunov <gorcunov@...il.com>
To:     Dmitry Safonov <dima@...sta.com>
Cc:     linux-kernel@...r.kernel.org, Andrei Vagin <avagin@...il.com>,
        Adrian Reber <adrian@...as.de>,
        Andrei Vagin <avagin@...nvz.org>,
        Andy Lutomirski <luto@...nel.org>,
        Andy Tucker <agtucker@...gle.com>,
        Arnd Bergmann <arnd@...db.de>,
        Christian Brauner <christian.brauner@...ntu.com>,
        Dmitry Safonov <0x7f454c46@...il.com>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
        Jeff Dike <jdike@...toit.com>, Oleg Nesterov <oleg@...hat.com>,
        Pavel Emelyanov <xemul@...tuozzo.com>,
        Shuah Khan <shuah@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        containers@...ts.linux-foundation.org, criu@...nvz.org,
        linux-api@...r.kernel.org, x86@...nel.org
Subject: Re: [PATCH 05/32] timerfd/timens: Take into account ns clock offsets

On Wed, Feb 06, 2019 at 12:10:39AM +0000, Dmitry Safonov wrote:
> From: Andrei Vagin <avagin@...il.com>
> 
> Make timerfd respect timens offsets.
> Provide two helpers timens_clock_to_host() timens_clock_from_host() that
> are useful to wire up timens to different kernel subsystems.
> Following patches will use timens_clock_from_host(), added here for
> completeness.
> 
> Signed-off-by: Andrei Vagin <avagin@...nvz.org>
> Co-developed-by: Dmitry Safonov <dima@...sta.com>
> Signed-off-by: Dmitry Safonov <dima@...sta.com>
> ---
>  fs/timerfd.c | 16 +++++++++++-----
>  1 file changed, 11 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/timerfd.c b/fs/timerfd.c
> index 803ca070d42e..c7ae1e371912 100644
> --- a/fs/timerfd.c
> +++ b/fs/timerfd.c
> @@ -26,6 +26,7 @@
>  #include <linux/syscalls.h>
>  #include <linux/compat.h>
>  #include <linux/rcupdate.h>
> +#include <linux/time_namespace.h>
>  
>  struct timerfd_ctx {
>  	union {
> @@ -433,22 +434,27 @@ SYSCALL_DEFINE2(timerfd_create, int, clockid, int, flags)
>  }
>  
>  static int do_timerfd_settime(int ufd, int flags, 
> -		const struct itimerspec64 *new,
> +		struct itimerspec64 *new,
>  		struct itimerspec64 *old)
>  {
>  	struct fd f;
>  	struct timerfd_ctx *ctx;
>  	int ret;
>  
> -	if ((flags & ~TFD_SETTIME_FLAGS) ||
> -		 !itimerspec64_valid(new))
> -		return -EINVAL;

Please don't defer this early test of a @flags value. Otherwise
if @flags is invalid you continue fget/put/clock-to-host even
if result will be dropped out then.