[Devel] [PATCH RH9 4/5] ve/time: Use ve_relative_clock in times() syscall and /proc/[pid]/stat

[Pavel Tikhomirov]

From: Kirill Tkhai <ktkhai at virtuozzo.com>

Extracted from "Initial patch".

Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>

(cherry picked from commit c7401d1672b6e50cb782da033c50a083c3d8371a)
Signed-off-by: Konstantin Khorenko <khorenko at virtuozzo.com>

+++
ve/proc/time: Port diff-ve-proc-report-real_start_time-in-_proc_PID_stat-if-CONFIG_VE

Author: Vladimir Davydov
Email: vdavydov at parallels.com
Subject: proc: report real_start_time in /proc/PID/stat if CONFIG_VE
Date: Mon, 14 Oct 2013 19:04:59 +0400

In case !CONFIG_VE, real_start_time is reported, so should be if
CONFIG_VE is on.

The difference between start_time and real_start_time is that the former
is the monotonic time of process start while the latter is bootbased,
i.e. includes time the system was suspended and uptime from the previous
boot in case the system was vzrebooted. Reporting start_time instead of
real_start_time leads to a wrong process etime reported by ps after
vzreboot or system suspend/resume.

https://jira.sw.ru/browse/PSBM-22925

Signed-off-by: Vladimir Davydov <vdavydov at parallels.com>

Acked-by: Stanislav Kinsbursky <skinsbursky at parallels.com>
=============================================================================

Author: Vladimir Davydov
Email: vdavydov at parallels.com
Subject: proc: fix negative start time in /proc/PID/stat
Date: Mon, 14 Oct 2013 19:05:01 +0400

Tasks inside a CT can have negative start time e.g. if the CT was
migrated from another hw node. In this case we'd better report 0 in
order not to confuse userspace and avoid warning trigger in
nsec_to_clock_t().

https://jira.sw.ru/browse/PSBM-22925

Signed-off-by: Vladimir Davydov <vdavydov at parallels.com>

Acked-by: Stanislav Kinsbursky <skinsbursky at parallels.com>
=============================================================================

Related to https://jira.sw.ru/browse/PSBM-33650

Signed-off-by: Vladimir Davydov <vdavydov at parallels.com>

(cherry picked from commit 7cc4ea4fdd6d0f25cbcfb8093e418f6e9647fcc1)
Signed-off-by: Konstantin Khorenko <khorenko at virtuozzo.com>

+++
ve/time: rework times() syscall and /proc/[pid]/stat to handle u64 time offsets

ve_struct.{start_time,real_start_time} are u64 now, change the code
correspondingly.

Drop duplicated fields start_timespec/real_start_timespec in ve_struct.

mFixes: f2716576136d ("ve/time: Use ve_relative_clock in times() syscall
and /proc/[pid]/stat")

Signed-off-by: Konstantin Khorenko <khorenko at virtuozzo.com>

(cherry picked from vz7 commit eca790eaed527bae7029b4ae1cd557ce847ac6c0)
Signed-off-by: Konstantin Khorenko <khorenko at virtuozzo.com>
Reviewed-by: Valeriy Vdovin <valeriy.vdovin at virtuozzo.com>

Changes vz9:
- split from process start time virtualization
- switch to time namespace

(cherry picked from vz8 commit 222870c58a3b4a284698e8cf7a692f7fea577b13)
Signed-off-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
---
 include/linux/ve.h | 23 +++++++++++++++++++++++
 kernel/sys.c       | 18 ++++++++++++++++++
 2 files changed, 41 insertions(+)

diff --git a/include/linux/ve.h b/include/linux/ve.h
index c2ff0602cb25..cc237ba41203 100644
--- a/include/linux/ve.h
+++ b/include/linux/ve.h
@@ -111,6 +111,29 @@ 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);
 
+static inline u64 ve_get_monotonic(struct ve_struct *ve)
+{
+	struct timespec64 tp = ns_to_timespec64(0);
+	struct time_namespace *time_ns;
+	struct nsproxy *ve_ns;
+
+	rcu_read_lock();
+	ve_ns = rcu_dereference(ve->ve_ns);
+	if (!ve_ns) {
+		rcu_read_unlock();
+		goto out;
+	}
+
+	time_ns = get_time_ns(ve_ns->time_ns);
+	rcu_read_unlock();
+
+	ktime_get_ts64(&tp);
+	tp = timespec64_add(tp, time_ns->offsets.monotonic);
+	put_time_ns(time_ns);
+out:
+	return timespec64_to_ns(&tp);
+}
+
 static u64 ve_get_uptime(struct ve_struct *ve)
 {
 	struct timespec64 tp = ns_to_timespec64(0);
diff --git a/kernel/sys.c b/kernel/sys.c
index ae566d26ab6e..3d4b35e0e636 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -986,6 +986,19 @@ static void do_sys_times(struct tms *tms)
 	tms->tms_cstime = nsec_to_clock_t(cstime);
 }
 
+#ifdef CONFIG_VE
+static u64 ve_relative_clock(void)
+{
+	u64 ve_now = ve_get_monotonic(get_exec_env());
+
+	/* VE not started, fallback to host time */
+	if (!ve_now)
+		ve_now = ktime_get_ns();
+
+	return nsec_to_clock_t(ve_now);
+}
+#endif
+
 SYSCALL_DEFINE1(times, struct tms __user *, tbuf)
 {
 	if (tbuf) {
@@ -995,8 +1008,13 @@ SYSCALL_DEFINE1(times, struct tms __user *, tbuf)
 		if (copy_to_user(tbuf, &tmp, sizeof(struct tms)))
 			return -EFAULT;
 	}
+#ifndef CONFIG_VE
 	force_successful_syscall_return();
 	return (long) jiffies_64_to_clock_t(get_jiffies_64());
+#else
+	force_successful_syscall_return();
+	return (long) ve_relative_clock();
+#endif
 }
 
 #ifdef CONFIG_COMPAT
-- 
2.31.1