linux-kernel - [tip: sched/core] sched/vtime: Record CPU under seqcount for kcpustat needs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <157234274286.29376.7269590620212447664.tip-bot2@tip-bot2>
Date:   Tue, 29 Oct 2019 09:52:22 -0000
From:   "tip-bot2 for Frederic Weisbecker" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Frederic Weisbecker <frederic@...nel.org>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Jacek Anaszewski <jacek.anaszewski@...il.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Pavel Machek <pavel@....cz>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Rik van Riel <riel@...riel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Wanpeng Li <wanpengli@...cent.com>,
        Yauheni Kaliuta <yauheni.kaliuta@...hat.com>,
        Ingo Molnar <mingo@...nel.org>, Borislav Petkov <bp@...en8.de>,
        linux-kernel@...r.kernel.org
Subject: [tip: sched/core] sched/vtime: Record CPU under seqcount for kcpustat needs

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     802f4a827f139f2581b3c50c69d20f8bf4c24af1
Gitweb:        https://git.kernel.org/tip/802f4a827f139f2581b3c50c69d20f8bf4c24af1
Author:        Frederic Weisbecker <frederic@...nel.org>
AuthorDate:    Wed, 16 Oct 2019 04:56:47 +02:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Tue, 29 Oct 2019 10:01:08 +01:00

sched/vtime: Record CPU under seqcount for kcpustat needs

In order to compute the kcpustat delta on a nohz CPU, we'll need to
fetch the task running on that target. Checking that its vtime
state snapshot actually refers to the relevant target involves recording
that CPU under the seqcount locked on task switch.

This is a step toward making kcpustat moving forward on full nohz CPUs.

Signed-off-by: Frederic Weisbecker <frederic@...nel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Jacek Anaszewski <jacek.anaszewski@...il.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Pavel Machek <pavel@....cz>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Rafael J . Wysocki <rjw@...ysocki.net>
Cc: Rik van Riel <riel@...riel.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Viresh Kumar <viresh.kumar@...aro.org>
Cc: Wanpeng Li <wanpengli@...cent.com>
Cc: Yauheni Kaliuta <yauheni.kaliuta@...hat.com>
Link: https://lkml.kernel.org/r/20191016025700.31277-2-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 include/linux/sched.h  | 1 +
 kernel/sched/cputime.c | 3 +++
 2 files changed, 4 insertions(+)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 2c2e56b..d5d0733 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -259,6 +259,7 @@ struct vtime {
 	seqcount_t		seqcount;
 	unsigned long long	starttime;
 	enum vtime_state	state;
+	unsigned int		cpu;
 	u64			utime;
 	u64			stime;
 	u64			gtime;
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index cef23c2..40f5816 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -818,6 +818,7 @@ void vtime_task_switch_generic(struct task_struct *prev)
 	else
 		__vtime_account_kernel(prev, vtime);
 	vtime->state = VTIME_INACTIVE;
+	vtime->cpu = -1;
 	write_seqcount_end(&vtime->seqcount);
 
 	vtime = &current->vtime;
@@ -825,6 +826,7 @@ void vtime_task_switch_generic(struct task_struct *prev)
 	write_seqcount_begin(&vtime->seqcount);
 	vtime->state = VTIME_SYS;
 	vtime->starttime = sched_clock();
+	vtime->cpu = smp_processor_id();
 	write_seqcount_end(&vtime->seqcount);
 }
 
@@ -837,6 +839,7 @@ void vtime_init_idle(struct task_struct *t, int cpu)
 	write_seqcount_begin(&vtime->seqcount);
 	vtime->state = VTIME_SYS;
 	vtime->starttime = sched_clock();
+	vtime->cpu = cpu;
 	write_seqcount_end(&vtime->seqcount);
 	local_irq_restore(flags);
 }