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From: Frederic Weisbecker <frederic@kernel.org>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Frederic Weisbecker <frederic@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Wanpeng Li <wanpengli@tencent.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Yauheni Kaliuta <yauheni.kaliuta@redhat.com>,
	Ingo Molnar <mingo@kernel.org>, Rik van Riel <riel@redhat.com>
Subject: [PATCH 25/25] sched/vtime: Clarify vtime_task_switch() argument layout
Date: Wed, 14 Nov 2018 03:46:09 +0100	[thread overview]
Message-ID: <1542163569-20047-26-git-send-email-frederic@kernel.org> (raw)
In-Reply-To: <1542163569-20047-1-git-send-email-frederic@kernel.org>

This function deals with the previous and next tasks during a context
switch. But only the previous is passed as an argument, the next task
being deduced from current. Make the code clearer by passing both
previous and next as arguments.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Yauheni Kaliuta <yauheni.kaliuta@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wanpeng Li <wanpengli@tencent.com>
Cc: Ingo Molnar <mingo@kernel.org>
---
 arch/ia64/include/asm/cputime.h    |  3 ++-
 arch/ia64/kernel/time.c            |  5 +++--
 arch/powerpc/include/asm/cputime.h |  8 +++++---
 arch/s390/kernel/vtime.c           | 13 +++++++------
 include/linux/vtime.h              | 17 +++++++++++------
 kernel/sched/core.c                |  2 +-
 kernel/sched/cputime.c             | 18 ++++++++++--------
 7 files changed, 39 insertions(+), 27 deletions(-)

diff --git a/arch/ia64/include/asm/cputime.h b/arch/ia64/include/asm/cputime.h
index 3d665c0..0bc90a1 100644
--- a/arch/ia64/include/asm/cputime.h
+++ b/arch/ia64/include/asm/cputime.h
@@ -19,7 +19,8 @@
 #define __IA64_CPUTIME_H
 
 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
-extern void arch_vtime_task_switch(struct task_struct *tsk);
+extern void arch_vtime_task_switch(struct task_struct *prev,
+				   struct task_struct *next);
 #endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
 
 #endif /* __IA64_CPUTIME_H */
diff --git a/arch/ia64/kernel/time.c b/arch/ia64/kernel/time.c
index 46a9798..908bd4f 100644
--- a/arch/ia64/kernel/time.c
+++ b/arch/ia64/kernel/time.c
@@ -105,10 +105,11 @@ void vtime_flush(struct task_struct *tsk)
  * accumulated times to the current process, and to prepare accounting on
  * the next process.
  */
-void arch_vtime_task_switch(struct task_struct *prev)
+void arch_vtime_task_switch(struct task_struct *prev,
+			    struct task_struct *next)
 {
 	struct thread_info *pi = task_thread_info(prev);
-	struct thread_info *ni = task_thread_info(current);
+	struct thread_info *ni = task_thread_info(next);
 
 	ni->ac_stamp = pi->ac_stamp;
 	ni->ac_stime = ni->ac_utime = 0;
diff --git a/arch/powerpc/include/asm/cputime.h b/arch/powerpc/include/asm/cputime.h
index ae73dc8..9d68040 100644
--- a/arch/powerpc/include/asm/cputime.h
+++ b/arch/powerpc/include/asm/cputime.h
@@ -47,7 +47,8 @@ static inline unsigned long cputime_to_usecs(const cputime_t ct)
  */
 #ifdef CONFIG_PPC64
 #define get_accounting(tsk)	(&get_paca()->accounting)
-static inline void arch_vtime_task_switch(struct task_struct *tsk) { }
+static inline void arch_vtime_task_switch(struct task_struct *prev,
+					  struct task_struct *next) { }
 #else
 #define get_accounting(tsk)	(&task_thread_info(tsk)->accounting)
 /*
@@ -55,9 +56,10 @@ static inline void arch_vtime_task_switch(struct task_struct *tsk) { }
  * accumulated times to the current process, and to prepare accounting on
  * the next process.
  */
-static inline void arch_vtime_task_switch(struct task_struct *prev)
+static inline void arch_vtime_task_switch(struct task_struct *prev,
+					  struct task_struct *next)
 {
-	struct cpu_accounting_data *acct = get_accounting(current);
+	struct cpu_accounting_data *acct = get_accounting(next);
 	struct cpu_accounting_data *acct0 = get_accounting(prev);
 
 	acct->starttime = acct0->starttime;
diff --git a/arch/s390/kernel/vtime.c b/arch/s390/kernel/vtime.c
index b6b888d..fcfeb63 100644
--- a/arch/s390/kernel/vtime.c
+++ b/arch/s390/kernel/vtime.c
@@ -191,7 +191,8 @@ static int do_account_vtime(struct task_struct *tsk)
 	return virt_timer_forward(user + guest + system + hardirq + softirq);
 }
 
-void vtime_task_switch(struct task_struct *prev)
+void vtime_task_switch(struct task_struct *prev,
+		       struct task_struct *next)
 {
 	do_account_vtime(prev);
 	prev->thread.user_timer = S390_lowcore.user_timer;
@@ -199,11 +200,11 @@ void vtime_task_switch(struct task_struct *prev)
 	prev->thread.system_timer = S390_lowcore.system_timer;
 	prev->thread.hardirq_timer = S390_lowcore.hardirq_timer;
 	prev->thread.softirq_timer = S390_lowcore.softirq_timer;
-	S390_lowcore.user_timer = current->thread.user_timer;
-	S390_lowcore.guest_timer = current->thread.guest_timer;
-	S390_lowcore.system_timer = current->thread.system_timer;
-	S390_lowcore.hardirq_timer = current->thread.hardirq_timer;
-	S390_lowcore.softirq_timer = current->thread.softirq_timer;
+	S390_lowcore.user_timer = next->thread.user_timer;
+	S390_lowcore.guest_timer = next->thread.guest_timer;
+	S390_lowcore.system_timer = next->thread.system_timer;
+	S390_lowcore.hardirq_timer = next->thread.hardirq_timer;
+	S390_lowcore.softirq_timer = next->thread.softirq_timer;
 }
 
 /*
diff --git a/include/linux/vtime.h b/include/linux/vtime.h
index b4566d5..188eace 100644
--- a/include/linux/vtime.h
+++ b/include/linux/vtime.h
@@ -16,7 +16,8 @@ struct task_struct;
 #if defined(CONFIG_VIRT_CPU_ACCOUNTING_NATIVE)
 
 static inline bool vtime_accounting_enabled_this_cpu(void) { return true; }
-extern void vtime_task_switch(struct task_struct *prev);
+extern void vtime_task_switch(struct task_struct *prev,
+			      struct task_struct *next);
 
 #elif defined(CONFIG_VIRT_CPU_ACCOUNTING_GEN)
 
@@ -51,19 +52,22 @@ static inline bool vtime_accounting_enabled_this_cpu(void)
 	return false;
 }
 
-extern void vtime_task_switch_generic(struct task_struct *prev);
+extern void vtime_task_switch_generic(struct task_struct *prev,
+				      struct task_struct *next);
 
-static inline void vtime_task_switch(struct task_struct *prev)
+static inline void vtime_task_switch(struct task_struct *prev,
+				     struct task_struct *next)
 {
 	if (vtime_accounting_enabled_this_cpu())
-		vtime_task_switch_generic(prev);
+		vtime_task_switch_generic(prev, next);
 }
 
 #else /* !CONFIG_VIRT_CPU_ACCOUNTING */
 
 static inline bool vtime_accounting_enabled_cpu(int cpu) {return false; }
 static inline bool vtime_accounting_enabled_this_cpu(void) { return false; }
-static inline void vtime_task_switch(struct task_struct *prev) { }
+static inline void vtime_task_switch(struct task_struct *prev,
+				     struct task_struct *next) { }
 
 #endif
 
@@ -78,7 +82,8 @@ static inline void vtime_account_kernel(struct task_struct *tsk) { }
 #endif /* !CONFIG_VIRT_CPU_ACCOUNTING */
 
 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
-extern void arch_vtime_task_switch(struct task_struct *tsk);
+extern void arch_vtime_task_switch(struct task_struct *prev,
+				   struct task_struct *next);
 extern void vtime_user_enter(struct task_struct *tsk);
 extern void vtime_user_exit(struct task_struct *tsk);
 extern void vtime_guest_enter(struct task_struct *tsk);
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index e8f0437..6e315b6 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2675,7 +2675,7 @@ static struct rq *finish_task_switch(struct task_struct *prev)
 	 * transition, resulting in a double drop.
 	 */
 	prev_state = prev->state;
-	vtime_task_switch(prev);
+	vtime_task_switch(prev, current);
 	perf_event_task_sched_in(prev, current);
 	finish_task(prev);
 	finish_lock_switch(rq);
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 3afde9f..c6a953d 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -421,7 +421,8 @@ static inline void irqtime_account_process_tick(struct task_struct *p, int user_
 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
 
 # ifndef __ARCH_HAS_VTIME_TASK_SWITCH
-void vtime_task_switch(struct task_struct *prev)
+void vtime_task_switch(struct task_struct *prev,
+		       struct task_struct *next)
 {
 	if (is_idle_task(prev))
 		vtime_account_idle(prev);
@@ -429,7 +430,7 @@ void vtime_task_switch(struct task_struct *prev)
 		vtime_account_kernel(prev);
 
 	vtime_flush(prev);
-	arch_vtime_task_switch(prev);
+	arch_vtime_task_switch(prev, next);
 }
 # endif
 
@@ -848,7 +849,8 @@ void vtime_account_idle(struct task_struct *tsk)
 	account_idle_time(get_vtime_delta(&tsk->vtime));
 }
 
-void vtime_task_switch_generic(struct task_struct *prev)
+void vtime_task_switch_generic(struct task_struct *prev,
+			       struct task_struct *next)
 {
 	struct vtime *vtime = &prev->vtime;
 	struct kernel_cpustat *kcpustat = kcpustat_this_cpu;
@@ -869,7 +871,7 @@ void vtime_task_switch_generic(struct task_struct *prev)
 		write_seqcount_end(&vtime->seqcount);
 	}
 
-	vtime = &current->vtime;
+	vtime = &next->vtime;
 
 	/*
 	 * Ignore the next task if it has been preempted after
@@ -881,18 +883,18 @@ void vtime_task_switch_generic(struct task_struct *prev)
 	}
 
 	write_seqcount_begin(&vtime->seqcount);
-	if (is_idle_task(current))
+	if (is_idle_task(next))
 		vtime->state = VTIME_IDLE;
-	else if (current->flags & PF_VCPU)
+	else if (next->flags & PF_VCPU)
 		vtime->state = VTIME_GUEST;
 	else
 		vtime->state = VTIME_SYS;
 	vtime->starttime = sched_clock();
 	vtime->cpu = smp_processor_id();
-	vtime->nice = (task_nice(current) > 0) ? 1 : 0;
+	vtime->nice = (task_nice(next) > 0) ? 1 : 0;
 	write_seqcount_end(&vtime->seqcount);
 
-	rcu_assign_pointer(kcpustat->curr, current);
+	rcu_assign_pointer(kcpustat->curr, next);
 }
 
 void vtime_init_idle(struct task_struct *t, int cpu)
-- 
2.7.4


      parent reply	other threads:[~2018-11-14  2:47 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-14  2:45 [PATCH 00/25] sched/nohz: Make kcpustat vtime aware (Fix kcpustat on nohz_full) Frederic Weisbecker
2018-11-14  2:45 ` [PATCH 01/25] sched/vtime: Fix guest/system mis-accounting on task switch Frederic Weisbecker
2018-11-14  2:45 ` [PATCH 02/25] sched/vtime: Protect idle accounting under vtime seqcount Frederic Weisbecker
2018-11-20 13:19   ` Peter Zijlstra
2018-11-14  2:45 ` [PATCH 03/25] vtime: Rename vtime_account_system() to vtime_account_kernel() Frederic Weisbecker
2018-11-14  2:45 ` [PATCH 04/25] vtime: Spare a seqcount lock/unlock cycle on context switch Frederic Weisbecker
2018-11-20 13:25   ` Peter Zijlstra
2019-09-25 14:42     ` Frederic Weisbecker
2018-11-14  2:45 ` [PATCH 05/25] sched/vtime: Record CPU under seqcount for kcpustat needs Frederic Weisbecker
2018-11-14  2:45 ` [PATCH 06/25] sched/cputime: Add vtime idle task state Frederic Weisbecker
2018-11-14  2:45 ` [PATCH 07/25] sched/cputime: Add vtime guest " Frederic Weisbecker
2018-11-14  2:45 ` [PATCH 08/25] vtime: Exit vtime before exit_notify() Frederic Weisbecker
2018-11-20 13:54   ` Peter Zijlstra
2018-11-14  2:45 ` [PATCH 09/25] kcpustat: Track running task following vtime sequences Frederic Weisbecker
2018-11-20 13:58   ` Peter Zijlstra
2018-11-14  2:45 ` [PATCH 10/25] context_tracking: Remove context_tracking_active() Frederic Weisbecker
2018-11-14  2:45 ` [PATCH 11/25] context_tracking: s/context_tracking_is_enabled/context_tracking_enabled() Frederic Weisbecker
2018-11-14  2:45 ` [PATCH 12/25] context_tracking: Rename context_tracking_is_cpu_enabled() to context_tracking_enabled_this_cpu() Frederic Weisbecker
2018-11-14  2:45 ` [PATCH 13/25] context_tracking: Introduce context_tracking_enabled_cpu() Frederic Weisbecker
2018-11-20 14:02   ` Peter Zijlstra
2018-11-14  2:45 ` [PATCH 14/25] sched/vtime: Rename vtime_accounting_cpu_enabled() to vtime_accounting_enabled_this_cpu() Frederic Weisbecker
2018-11-14  2:45 ` [PATCH 15/25] sched/vtime: Introduce vtime_accounting_enabled_cpu() Frederic Weisbecker
2018-11-20 14:04   ` Peter Zijlstra
2018-11-14  2:46 ` [PATCH 16/25] sched/cputime: Allow to pass cputime index on user/guest accounting Frederic Weisbecker
2018-11-14  2:46 ` [PATCH 17/25] sched/cputime: Standardize the kcpustat index based accounting functions Frederic Weisbecker
2018-11-14  2:46 ` [PATCH 18/25] vtime: Track nice-ness on top of context switch Frederic Weisbecker
2018-11-20 14:09   ` Peter Zijlstra
2018-11-14  2:46 ` [PATCH 19/25] sched/vite: Handle nice updates under vtime Frederic Weisbecker
2018-11-20 14:17   ` Peter Zijlstra
2018-11-26 15:53     ` Frederic Weisbecker
2018-11-26 16:11       ` Peter Zijlstra
2018-11-26 18:41         ` Frederic Weisbecker
2018-11-14  2:46 ` [PATCH 20/25] sched/kcpustat: Introduce vtime-aware kcpustat accessor Frederic Weisbecker
2018-11-20 14:23   ` Peter Zijlstra
2018-11-20 22:40     ` Frederic Weisbecker
2018-11-21  8:18       ` Peter Zijlstra
2018-11-21  8:35         ` Peter Zijlstra
2018-11-21 16:33         ` Frederic Weisbecker
2018-11-14  2:46 ` [PATCH 21/25] procfs: Use vtime aware " Frederic Weisbecker
2018-11-20 14:24   ` Peter Zijlstra
2018-11-20 22:31     ` Frederic Weisbecker
2018-11-14  2:46 ` [PATCH 22/25] cpufreq: " Frederic Weisbecker
2018-11-14  2:46 ` [PATCH 23/25] leds: Use vtime aware kcpustat accessors Frederic Weisbecker
2018-11-14  2:46 ` [PATCH 24/25] rackmeter: " Frederic Weisbecker
2018-11-14  2:46 ` Frederic Weisbecker [this message]

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