[Devel] [PATCH rh8] ve/posix-timers: reference ve monotonic clock from ve start (v2)
Kirill Tkhai
ktkhai at virtuozzo.com
Mon Oct 12 15:49:30 MSK 2020
On 09.10.2020 14:02, Konstantin Khorenko wrote:
> From: Kirill Tkhai <ktkhai at parallels.com>
>
> So that CLOCK_MONOTONIC will be monotonic even if ve is migrated to
> another hw node.
>
> Note, translating ve <-> abs time in clock_settime and timer_settime is
> not necessary because (1) clock_settime won't set monotonic clock and
> (2) timer_gettime always returns relative time.
>
> https://jira.sw.ru/browse/PSBM-13860
>
> diff-posix_timers-reference-ct-monotonic-clock-from-ct-start
>
> Signed-off-by: Vladimir Davydov <vdavydov at parallels.com>
>
> Acked-by: Pavel Emelyanov <xemul at parallels.com>
> Signed-off-by: Kirill Tkhai <ktkhai at parallels.com>
>
> +++
> ve/posix-timers: reference ve monotonic clock from start in clock_nanosleep
>
> This is an addition to diff-posix_timers-reference-ct-monotonic-clock-from-ct-start
>
> Otherwise, apps that use sys_clock_nanosleep() to suspend their
> execution can hang after ve migration.
>
> diff-posix-timers-reference-ve-monotonic-clock-from-ve-start-in-clock_nanosleep
>
> Signed-off-by: Vladimir Davydov <vdavydov at parallels.com>
>
> Acked-by: Konstantin Khlebnikov <khlebnikov at openvz.org>
> Acked-by: Pavel Emelyanov <xemul at parallels.com>
> Signed-off-by: Kirill Tkhai <ktkhai at parallels.com>
>
> +++
> timers: Port diff-ve-timers-convert-ve-monotonic-to-abs-time-when-setting-timerfd-2
>
> Need this for docker, as sometimes systemd-tmpfiles-clean.timer inside
> a PCS7 CT is spamming dbus with requests to start corresponding service.
> And at the same time Docker tries to create cgroup for container and
> attach it to hierarchies like memory and blkio.
>
> That is because systemd timer was triggered with non-virtualized timerfd
> using plain host clock but check that timer is successfull uses
> virtualized clock_gettime and don't pass before proper(in-container)
> timer activation. And timers charges again and again starts service
> got in busy loop.
>
> https://jira.sw.ru/browse/PSBM-34017
>
> v2: move the stubs to ve.h
>
> Port the following RH6 commit:
>
> Author: Vladimir Davydov
> Email: vdavydov at parallels.com
> Subject: fs: convert ve monotonic to abs time when setting timerfd
> Date: Fri, 15 Feb 2013 11:57:09 +0400
>
> * [timers] corrected TFD_TIMER_ABSTIME timer handling,
> the issue led to high cpu usage inside a Fedora 18 CT
> by 'init' process (PSBM-18284)
>
> Monotonic time inside container, as it can be obtained using various
> system calls such as clock_gettime, is reported since start of the container,
> not since start of the whole system. This was made in order to avoid time
> issues while a container is migrated between different physical hosts, but this
> also introduced a lot of problems in time- related system calls because
> absolute monotonic time, which is in fact relative to container, passed to those
> system calls must be converted to system-wide monotonic time, which is used by
> kernel hrtimers.
>
> One of those buggy system calls is timerfd_settime which accepts as an
> argument absolute time if flag TFD_TIMER_ABSTIME is specified.
>
> The patch fixes it by converting container monotonic time to system-
> wide monotonic time using the monotonic_ve_to_abs() function, which was
> introduced earlier and is now exported for that reason.
>
> https://jira.sw.ru/browse/PSBM-18284
>
> Signed-off-by: Vladimir Davydov <vdavydov at parallels.com>
>
> Signed-off-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
> Signed-off-by: Kirill Tkhai <ktkhai at odin.com>
> Reviewed-by: Vladimir Davydov <vdavydov at parallels.com>
>
> (cherry picked from vz7 commit 869542c24c41c0578b47d2ef83cfa63427e0e5e1)
> Signed-off-by: Konstantin Khorenko <khorenko at virtuozzo.com>
>
> +++
> timers should not get negative argument
>
> This patch fixes 25-sec delay on login into systemd based containers.
>
> Userspace application can set timer for past
> and expect that the timer will be expired immediately.
>
> This can do not work as expected inside migrated containers.
> Translated argument provided to timer can become negative,
> and according timer will sleep a very long time.
>
> https://jira.sw.ru/browse/PSBM-48475
>
> CC: Vladimir Davydov <vdavydov at virtuozzo.com>
> CC: Konstantin Khorenko <khorenko at virtuozzo.com>
> Signed-off-by: Vasily Averin <vvs at virtuozzo.com>
> Acked-by: Cyrill Gorcunov <gorcunov at openvz.org>
>
> (cherry picked from vz7 commit a71fa19facb00472e47760255ab2e6fa16885732)
> Signed-off-by: Konstantin Khorenko <khorenko at virtuozzo.com>
> ---
> fs/timerfd.c | 8 ++++--
> include/linux/ve.h | 8 ++++++
> kernel/time/posix-timers.c | 55 +++++++++++++++++++++++++++++++++++++-
> 3 files changed, 68 insertions(+), 3 deletions(-)
>
> diff --git a/fs/timerfd.c b/fs/timerfd.c
> index cdad49da3ff7..59ed38c29941 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/ve.h>
>
> struct timerfd_ctx {
> union {
> @@ -432,8 +433,8 @@ SYSCALL_DEFINE2(timerfd_create, int, clockid, int, flags)
> return ufd;
> }
>
> -static int do_timerfd_settime(int ufd, int flags,
> - const struct itimerspec64 *new,
> +static int do_timerfd_settime(int ufd, int flags,
> + struct itimerspec64 *new,
> struct itimerspec64 *old)
> {
> struct fd f;
> @@ -493,6 +494,9 @@ static int do_timerfd_settime(int ufd, int flags,
> /*
> * Re-program the timer to the new value ...
> */
> + if ((flags & TFD_TIMER_ABSTIME) &&
> + (new->it_value.tv_sec || new->it_value.tv_nsec))
> + monotonic_ve_to_abs(ctx->clockid, &new->it_value);
> ret = timerfd_setup(ctx, flags, new);
>
> spin_unlock_irq(&ctx->wqh.lock);
> diff --git a/include/linux/ve.h b/include/linux/ve.h
> index 0db98e8e08c1..ec7dc522ac1f 100644
> --- a/include/linux/ve.h
> +++ b/include/linux/ve.h
> @@ -129,6 +129,9 @@ static inline struct ve_struct *css_to_ve(struct cgroup_subsys_state *css)
>
> extern struct cgroup_subsys_state *ve_get_init_css(struct ve_struct *ve, int subsys_id);
>
> +extern void monotonic_abs_to_ve(clockid_t which_clock, struct timespec64 *tp);
> +extern void monotonic_ve_to_abs(clockid_t which_clock, struct timespec64 *tp);
> +
> #define ve_feature_set(ve, f) \
> !!((ve)->features & VE_FEATURE_##f)
>
> @@ -166,6 +169,11 @@ static inline struct user_namespace *ve_init_user_ns(void)
> static inline int vz_security_family_check(struct net *net, int family) { return 0; }
> static inline int vz_security_protocol_check(struct net *net, int protocol) { return 0; }
>
> +static inline void monotonic_abs_to_ve(clockid_t which_clock,
> + struct timespec64 *tp) { }
> +static inline void monotonic_ve_to_abs(clockid_t which_clock,
> + struct timepsec64 *tp) { }
> +
> #endif /* CONFIG_VE */
>
> #endif /* _LINUX_VE_H */
> diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
> index 3d54de0a28bc..ad6f0ab7a66f 100644
> --- a/kernel/time/posix-timers.c
> +++ b/kernel/time/posix-timers.c
> @@ -51,6 +51,7 @@
> #include <linux/hashtable.h>
> #include <linux/compat.h>
> #include <linux/nospec.h>
> +#include <linux/ve.h>
>
> #include "timekeeping.h"
> #include "posix-timers.h"
> @@ -76,6 +77,46 @@ static const struct k_clock * const posix_clocks[];
> static const struct k_clock *clockid_to_kclock(const clockid_t id);
> static const struct k_clock clock_realtime, clock_monotonic;
>
> +#define clock_is_monotonic(which_clock) \
> + ((which_clock) == CLOCK_MONOTONIC || \
> + (which_clock) == CLOCK_MONOTONIC_RAW || \
> + (which_clock) == CLOCK_MONOTONIC_COARSE)
> +
> +#ifdef CONFIG_VE
> +static struct timespec64 zero_time;
> +
> +void monotonic_abs_to_ve(clockid_t which_clock, struct timespec64 *tp)
> +{
> + struct timespec64 offset;
> +
> + if (!clock_is_monotonic(which_clock))
> + return;
> +
> + offset = ns_to_timespec64(get_exec_env()->start_time);
> + set_normalized_timespec64(tp,
> + tp->tv_sec - offset.tv_sec,
> + tp->tv_nsec - offset.tv_nsec);
> +}
> +
> +void monotonic_ve_to_abs(clockid_t which_clock, struct timespec64 *tp)
> +{
> + struct timespec64 offset;
> +
> + if (!clock_is_monotonic(which_clock))
> + return;
> +
> + offset = ns_to_timespec64(get_exec_env()->start_time);
> + set_normalized_timespec64(tp,
> + tp->tv_sec + offset.tv_sec,
> + tp->tv_nsec + offset.tv_nsec);
> +
> + if (timespec64_compare(tp, &zero_time) <= 0) {
> + tp->tv_sec = 0;
> + tp->tv_nsec = 1;
> + }
> +}
> +#endif
> +
> /*
> * we assume that the new SIGEV_THREAD_ID shares no bits with the other
> * SIGEV values. Here we put out an error if this assumption fails.
> @@ -895,6 +936,9 @@ static int do_timer_settime(timer_t timer_id, int flags,
> if (!timr)
> return -EINVAL;
>
> + if ((flags & TIMER_ABSTIME) &&
> + (new_spec64->it_value.tv_sec || new_spec64->it_value.tv_nsec))
> + monotonic_ve_to_abs(timr->it_clock, &new_spec64->it_value);
> kc = timr->kclock;
> if (WARN_ON_ONCE(!kc || !kc->timer_set))
> error = -EINVAL;
> @@ -1072,6 +1116,7 @@ SYSCALL_DEFINE2(clock_gettime, const clockid_t, which_clock,
>
> error = kc->clock_get(which_clock, &kernel_tp);
>
> + monotonic_abs_to_ve(which_clock, &kernel_tp);
> if (!error && put_timespec64(&kernel_tp, tp))
> error = -EFAULT;
>
> @@ -1148,6 +1193,7 @@ COMPAT_SYSCALL_DEFINE2(clock_gettime, clockid_t, which_clock,
>
> err = kc->clock_get(which_clock, &ts);
>
> + monotonic_abs_to_ve(which_clock, &ts);
> if (!err && compat_put_timespec64(&ts, tp))
> err = -EFAULT;
>
> @@ -1233,8 +1279,13 @@ SYSCALL_DEFINE4(clock_nanosleep, const clockid_t, which_clock, int, flags,
>
> if (!timespec64_valid(&t))
> return -EINVAL;
> +
> if (flags & TIMER_ABSTIME)
Is this string going to be deleted?
> +
> + if (flags & TIMER_ABSTIME) {
> + monotonic_ve_to_abs(which_clock, &t);
> rmtp = NULL;
> + }
> current->restart_block.nanosleep.type = rmtp ? TT_NATIVE : TT_NONE;
> current->restart_block.nanosleep.rmtp = rmtp;
>
> @@ -1260,8 +1311,10 @@ COMPAT_SYSCALL_DEFINE4(clock_nanosleep, clockid_t, which_clock, int, flags,
>
> if (!timespec64_valid(&t))
> return -EINVAL;
> - if (flags & TIMER_ABSTIME)
> + if (flags & TIMER_ABSTIME) {
> + monotonic_ve_to_abs(which_clock, &t);
> rmtp = NULL;
> + }
> current->restart_block.nanosleep.type = rmtp ? TT_COMPAT : TT_NONE;
> current->restart_block.nanosleep.compat_rmtp = rmtp;
>
>
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