[GIT PULL] cputime: cleanups

[GIT PULL] cputime: cleanups

[Frederic Weisbecker]

Ingo,

Please pull the latest sched cleanups branch that can be found at

git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git
	tags/sched-cputime-for-mingo

for you to pull the HEAD 1b2852b152be5150fbef7b585388ec43cf6f4415
("vtime: Warn if irqs aren't disabled on system time accounting APIs")

Thanks.

---
Some more cputime cleanups:

* Get rid of underscores polluting the vtime namespace

* Consolidate context switch and tick handling

* Improve debuggability by detecting irq unsafe callers

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
---

Frederic Weisbecker (5):
  vtime: Remove the underscore prefix invasion
  vtime: Explicitly account pending user time on process tick
  vtime: Consolidate a bit the ctx switch code
  vtime: No need to disable irqs on vtime_account()
  vtime: Warn if irqs aren't disabled on system time accounting APIs

 arch/ia64/include/asm/cputime.h    |    2 ++
 arch/ia64/kernel/time.c            |   26 ++++++--------------------
 arch/powerpc/include/asm/cputime.h |    2 ++
 arch/powerpc/kernel/time.c         |   24 ++++++++++--------------
 arch/s390/include/asm/cputime.h    |    1 +
 arch/s390/kernel/vtime.c           |   13 ++++++++++---
 include/linux/kernel_stat.h        |    8 ++++++++
 include/linux/kvm_host.h           |    4 ++--
 include/linux/vtime.h              |    9 +++++----
 kernel/sched/cputime.c             |   31 +++++++++++++++++++------------
 10 files changed, 65 insertions(+), 55 deletions(-)

[PATCH 1/5] vtime: Remove the underscore prefix invasion

[Frederic Weisbecker]

Prepending irq-unsafe vtime APIs with underscores was actually
a bad idea as the result is a big mess in the API namespace that
is even waiting to be further extended. Also these helpers
are always called from irq safe callers except kvm. Just
provide a vtime_account_system_irqsafe() for this specific
case so that we can remove the underscore prefix on other
vtime functions.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
---
 arch/ia64/kernel/time.c    |    8 ++++----
 arch/powerpc/kernel/time.c |    4 ++--
 arch/s390/kernel/vtime.c   |    4 ++--
 include/linux/kvm_host.h   |    4 ++--
 include/linux/vtime.h      |    8 ++++----
 kernel/sched/cputime.c     |   12 ++++++------
 6 files changed, 20 insertions(+), 20 deletions(-)

diff --git a/arch/ia64/kernel/time.c b/arch/ia64/kernel/time.c
index 5e48503..f638821 100644
--- a/arch/ia64/kernel/time.c
+++ b/arch/ia64/kernel/time.c
@@ -106,9 +106,9 @@ void vtime_task_switch(struct task_struct *prev)
 	struct thread_info *ni = task_thread_info(current);
 
 	if (idle_task(smp_processor_id()) != prev)
-		__vtime_account_system(prev);
+		vtime_account_system(prev);
 	else
-		__vtime_account_idle(prev);
+		vtime_account_idle(prev);
 
 	vtime_account_user(prev);
 
@@ -135,14 +135,14 @@ static cputime_t vtime_delta(struct task_struct *tsk)
 	return delta_stime;
 }
 
-void __vtime_account_system(struct task_struct *tsk)
+void vtime_account_system(struct task_struct *tsk)
 {
 	cputime_t delta = vtime_delta(tsk);
 
 	account_system_time(tsk, 0, delta, delta);
 }
 
-void __vtime_account_idle(struct task_struct *tsk)
+void vtime_account_idle(struct task_struct *tsk)
 {
 	account_idle_time(vtime_delta(tsk));
 }
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 0db456f..ce4cb77 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -336,7 +336,7 @@ static u64 vtime_delta(struct task_struct *tsk,
 	return delta;
 }
 
-void __vtime_account_system(struct task_struct *tsk)
+void vtime_account_system(struct task_struct *tsk)
 {
 	u64 delta, sys_scaled, stolen;
 
@@ -346,7 +346,7 @@ void __vtime_account_system(struct task_struct *tsk)
 		account_steal_time(stolen);
 }
 
-void __vtime_account_idle(struct task_struct *tsk)
+void vtime_account_idle(struct task_struct *tsk)
 {
 	u64 delta, sys_scaled, stolen;
 
diff --git a/arch/s390/kernel/vtime.c b/arch/s390/kernel/vtime.c
index 783e988..80d1dbc 100644
--- a/arch/s390/kernel/vtime.c
+++ b/arch/s390/kernel/vtime.c
@@ -140,9 +140,9 @@ void vtime_account(struct task_struct *tsk)
 }
 EXPORT_SYMBOL_GPL(vtime_account);
 
-void __vtime_account_system(struct task_struct *tsk)
+void vtime_account_system(struct task_struct *tsk)
 __attribute__((alias("vtime_account")));
-EXPORT_SYMBOL_GPL(__vtime_account_system);
+EXPORT_SYMBOL_GPL(vtime_account_system);
 
 void __kprobes vtime_stop_cpu(void)
 {
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 0e2212f..f17158b 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -741,7 +741,7 @@ static inline void kvm_guest_enter(void)
 	 * This is running in ioctl context so we can avoid
 	 * the call to vtime_account() with its unnecessary idle check.
 	 */
-	vtime_account_system(current);
+	vtime_account_system_irqsafe(current);
 	current->flags |= PF_VCPU;
 	/* KVM does not hold any references to rcu protected data when it
 	 * switches CPU into a guest mode. In fact switching to a guest mode
@@ -759,7 +759,7 @@ static inline void kvm_guest_exit(void)
 	 * This is running in ioctl context so we can avoid
 	 * the call to vtime_account() with its unnecessary idle check.
 	 */
-	vtime_account_system(current);
+	vtime_account_system_irqsafe(current);
 	current->flags &= ~PF_VCPU;
 }
 
diff --git a/include/linux/vtime.h b/include/linux/vtime.h
index 0c2a2d3..5ad13c3 100644
--- a/include/linux/vtime.h
+++ b/include/linux/vtime.h
@@ -5,14 +5,14 @@ struct task_struct;
 
 #ifdef CONFIG_VIRT_CPU_ACCOUNTING
 extern void vtime_task_switch(struct task_struct *prev);
-extern void __vtime_account_system(struct task_struct *tsk);
 extern void vtime_account_system(struct task_struct *tsk);
-extern void __vtime_account_idle(struct task_struct *tsk);
+extern void vtime_account_system_irqsafe(struct task_struct *tsk);
+extern void vtime_account_idle(struct task_struct *tsk);
 extern void vtime_account(struct task_struct *tsk);
 #else
 static inline void vtime_task_switch(struct task_struct *prev) { }
-static inline void __vtime_account_system(struct task_struct *tsk) { }
 static inline void vtime_account_system(struct task_struct *tsk) { }
+static inline void vtime_account_system_irqsafe(struct task_struct *tsk) { }
 static inline void vtime_account(struct task_struct *tsk) { }
 #endif
 
@@ -40,7 +40,7 @@ static inline void vtime_account_irq_enter(struct task_struct *tsk)
 static inline void vtime_account_irq_exit(struct task_struct *tsk)
 {
 	/* On hard|softirq exit we always account to hard|softirq cputime */
-	__vtime_account_system(tsk);
+	vtime_account_system(tsk);
 	irqtime_account_irq(tsk);
 }
 
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 8d859da..c0aa1ba 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -433,20 +433,20 @@ void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
 	*st = cputime.stime;
 }
 
-void vtime_account_system(struct task_struct *tsk)
+void vtime_account_system_irqsafe(struct task_struct *tsk)
 {
 	unsigned long flags;
 
 	local_irq_save(flags);
-	__vtime_account_system(tsk);
+	vtime_account_system(tsk);
 	local_irq_restore(flags);
 }
-EXPORT_SYMBOL_GPL(vtime_account_system);
+EXPORT_SYMBOL_GPL(vtime_account_system_irqsafe);
 
 /*
  * Archs that account the whole time spent in the idle task
  * (outside irq) as idle time can rely on this and just implement
- * __vtime_account_system() and __vtime_account_idle(). Archs that
+ * vtime_account_system() and vtime_account_idle(). Archs that
  * have other meaning of the idle time (s390 only includes the
  * time spent by the CPU when it's in low power mode) must override
  * vtime_account().
@@ -459,9 +459,9 @@ void vtime_account(struct task_struct *tsk)
 	local_irq_save(flags);
 
 	if (in_interrupt() || !is_idle_task(tsk))
-		__vtime_account_system(tsk);
+		vtime_account_system(tsk);
 	else
-		__vtime_account_idle(tsk);
+		vtime_account_idle(tsk);
 
 	local_irq_restore(flags);
 }
-- 
1.7.5.4

[PATCH 2/5] vtime: Explicitly account pending user time on process tick

[Frederic Weisbecker]

All vtime implementations just flush the user time on process
tick. Consolidate that in generic code by calling a user time
accounting helper. This avoids an indirect call in ia64 and
prepare to also consolidate vtime context switch code.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
---
 arch/ia64/kernel/time.c     |   11 +----------
 arch/powerpc/kernel/time.c  |   14 +++++++-------
 arch/s390/kernel/vtime.c    |    7 ++++++-
 include/linux/kernel_stat.h |    8 ++++++++
 include/linux/vtime.h       |    1 +
 5 files changed, 23 insertions(+), 18 deletions(-)

diff --git a/arch/ia64/kernel/time.c b/arch/ia64/kernel/time.c
index f638821..834c78b 100644
--- a/arch/ia64/kernel/time.c
+++ b/arch/ia64/kernel/time.c
@@ -83,7 +83,7 @@ static struct clocksource *itc_clocksource;
 
 extern cputime_t cycle_to_cputime(u64 cyc);
 
-static void vtime_account_user(struct task_struct *tsk)
+void vtime_account_user(struct task_struct *tsk)
 {
 	cputime_t delta_utime;
 	struct thread_info *ti = task_thread_info(tsk);
@@ -147,15 +147,6 @@ void vtime_account_idle(struct task_struct *tsk)
 	account_idle_time(vtime_delta(tsk));
 }
 
-/*
- * Called from the timer interrupt handler to charge accumulated user time
- * to the current process.  Must be called with interrupts disabled.
- */
-void account_process_tick(struct task_struct *p, int user_tick)
-{
-	vtime_account_user(p);
-}
-
 #endif /* CONFIG_VIRT_CPU_ACCOUNTING */
 
 static irqreturn_t
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index ce4cb77..a667aaf 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -355,15 +355,15 @@ void vtime_account_idle(struct task_struct *tsk)
 }
 
 /*
- * Transfer the user and system times accumulated in the paca
- * by the exception entry and exit code to the generic process
- * user and system time records.
+ * Transfer the user time accumulated in the paca
+ * by the exception entry and exit code to the generic
+ * process user time records.
  * Must be called with interrupts disabled.
- * Assumes that vtime_account() has been called recently
- * (i.e. since the last entry from usermode) so that
+ * Assumes that vtime_account_system/idle() has been called
+ * recently (i.e. since the last entry from usermode) so that
  * get_paca()->user_time_scaled is up to date.
  */
-void account_process_tick(struct task_struct *tsk, int user_tick)
+void vtime_account_user(struct task_struct *tsk)
 {
 	cputime_t utime, utimescaled;
 
@@ -378,7 +378,7 @@ void account_process_tick(struct task_struct *tsk, int user_tick)
 void vtime_task_switch(struct task_struct *prev)
 {
 	vtime_account(prev);
-	account_process_tick(prev, 0);
+	vtime_account_user(prev);
 }
 
 #else /* ! CONFIG_VIRT_CPU_ACCOUNTING */
diff --git a/arch/s390/kernel/vtime.c b/arch/s390/kernel/vtime.c
index 80d1dbc..7c6d861 100644
--- a/arch/s390/kernel/vtime.c
+++ b/arch/s390/kernel/vtime.c
@@ -112,7 +112,12 @@ void vtime_task_switch(struct task_struct *prev)
 	S390_lowcore.system_timer = ti->system_timer;
 }
 
-void account_process_tick(struct task_struct *tsk, int user_tick)
+/*
+ * In s390, accounting pending user time also implies
+ * accounting system time in order to correctly compute
+ * the stolen time accounting.
+ */
+void vtime_account_user(struct task_struct *tsk)
 {
 	if (do_account_vtime(tsk, HARDIRQ_OFFSET))
 		virt_timer_expire();
diff --git a/include/linux/kernel_stat.h b/include/linux/kernel_stat.h
index 1865b1f..66b7078 100644
--- a/include/linux/kernel_stat.h
+++ b/include/linux/kernel_stat.h
@@ -127,7 +127,15 @@ extern void account_system_time(struct task_struct *, int, cputime_t, cputime_t)
 extern void account_steal_time(cputime_t);
 extern void account_idle_time(cputime_t);
 
+#ifdef CONFIG_VIRT_CPU_ACCOUNTING
+static inline void account_process_tick(struct task_struct *tsk, int user)
+{
+	vtime_account_user(tsk);
+}
+#else
 extern void account_process_tick(struct task_struct *, int user);
+#endif
+
 extern void account_steal_ticks(unsigned long ticks);
 extern void account_idle_ticks(unsigned long ticks);
 
diff --git a/include/linux/vtime.h b/include/linux/vtime.h
index 5ad13c3..ae30ab5 100644
--- a/include/linux/vtime.h
+++ b/include/linux/vtime.h
@@ -8,6 +8,7 @@ extern void vtime_task_switch(struct task_struct *prev);
 extern void vtime_account_system(struct task_struct *tsk);
 extern void vtime_account_system_irqsafe(struct task_struct *tsk);
 extern void vtime_account_idle(struct task_struct *tsk);
+extern void vtime_account_user(struct task_struct *tsk);
 extern void vtime_account(struct task_struct *tsk);
 #else
 static inline void vtime_task_switch(struct task_struct *prev) { }
-- 
1.7.5.4

[PATCH 3/5] vtime: Consolidate a bit the ctx switch code

[Frederic Weisbecker]

On ia64 and powerpc, vtime context switch only consists
in flushing system and user pending time, plus a few
arch housekeeping.

Consolidate that into a generic implementation. s390 is
a special case because pending user and system time accounting
there is hard to dissociate. So it's keeping its own implementation.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
---
 arch/ia64/include/asm/cputime.h    |    2 ++
 arch/ia64/kernel/time.c            |    9 +--------
 arch/powerpc/include/asm/cputime.h |    2 ++
 arch/powerpc/kernel/time.c         |    6 ------
 arch/s390/include/asm/cputime.h    |    1 +
 kernel/sched/cputime.c             |   13 +++++++++++++
 6 files changed, 19 insertions(+), 14 deletions(-)

diff --git a/arch/ia64/include/asm/cputime.h b/arch/ia64/include/asm/cputime.h
index 3deac95..7fcf7f0 100644
--- a/arch/ia64/include/asm/cputime.h
+++ b/arch/ia64/include/asm/cputime.h
@@ -103,5 +103,7 @@ static inline void cputime_to_timeval(const cputime_t ct, struct timeval *val)
 #define cputime64_to_clock_t(__ct)	\
 	cputime_to_clock_t((__force cputime_t)__ct)
 
+extern void arch_vtime_task_switch(struct task_struct *tsk);
+
 #endif /* CONFIG_VIRT_CPU_ACCOUNTING */
 #endif /* __IA64_CPUTIME_H */
diff --git a/arch/ia64/kernel/time.c b/arch/ia64/kernel/time.c
index 834c78b..c9a7d2e 100644
--- a/arch/ia64/kernel/time.c
+++ b/arch/ia64/kernel/time.c
@@ -100,18 +100,11 @@ void vtime_account_user(struct task_struct *tsk)
  * accumulated times to the current process, and to prepare accounting on
  * the next process.
  */
-void vtime_task_switch(struct task_struct *prev)
+void arch_vtime_task_switch(struct task_struct *prev)
 {
 	struct thread_info *pi = task_thread_info(prev);
 	struct thread_info *ni = task_thread_info(current);
 
-	if (idle_task(smp_processor_id()) != prev)
-		vtime_account_system(prev);
-	else
-		vtime_account_idle(prev);
-
-	vtime_account_user(prev);
-
 	pi->ac_stamp = ni->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 487d46f..483733b 100644
--- a/arch/powerpc/include/asm/cputime.h
+++ b/arch/powerpc/include/asm/cputime.h
@@ -228,6 +228,8 @@ static inline cputime_t clock_t_to_cputime(const unsigned long clk)
 
 #define cputime64_to_clock_t(ct)	cputime_to_clock_t((cputime_t)(ct))
 
+static inline void arch_vtime_task_switch(struct task_struct *tsk) { }
+
 #endif /* __KERNEL__ */
 #endif /* CONFIG_VIRT_CPU_ACCOUNTING */
 #endif /* __POWERPC_CPUTIME_H */
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index a667aaf..3486cfa 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -375,12 +375,6 @@ void vtime_account_user(struct task_struct *tsk)
 	account_user_time(tsk, utime, utimescaled);
 }
 
-void vtime_task_switch(struct task_struct *prev)
-{
-	vtime_account(prev);
-	vtime_account_user(prev);
-}
-
 #else /* ! CONFIG_VIRT_CPU_ACCOUNTING */
 #define calc_cputime_factors()
 #endif
diff --git a/arch/s390/include/asm/cputime.h b/arch/s390/include/asm/cputime.h
index 023d5ae..d2ff4137 100644
--- a/arch/s390/include/asm/cputime.h
+++ b/arch/s390/include/asm/cputime.h
@@ -14,6 +14,7 @@
 
 
 #define __ARCH_HAS_VTIME_ACCOUNT
+#define __ARCH_HAS_VTIME_TASK_SWITCH
 
 /* We want to use full resolution of the CPU timer: 2**-12 micro-seconds. */
 
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index c0aa1ba..2e8d34a 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -443,6 +443,19 @@ void vtime_account_system_irqsafe(struct task_struct *tsk)
 }
 EXPORT_SYMBOL_GPL(vtime_account_system_irqsafe);
 
+#ifndef __ARCH_HAS_VTIME_TASK_SWITCH
+void vtime_task_switch(struct task_struct *prev)
+{
+	if (is_idle_task(prev))
+		vtime_account_idle(prev);
+	else
+		vtime_account_system(prev);
+
+	vtime_account_user(prev);
+	arch_vtime_task_switch(prev);
+}
+#endif
+
 /*
  * Archs that account the whole time spent in the idle task
  * (outside irq) as idle time can rely on this and just implement
-- 
1.7.5.4

[PATCH 4/5] vtime: No need to disable irqs on vtime_account()

[Frederic Weisbecker]

vtime_account() is only called from irq entry. irqs
are always disabled at this point so we can safely
remove the irq disabling guards on that function.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
---
 kernel/sched/cputime.c |    6 ------
 1 files changed, 0 insertions(+), 6 deletions(-)

diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 2e8d34a..80b2fd5 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -467,16 +467,10 @@ void vtime_task_switch(struct task_struct *prev)
 #ifndef __ARCH_HAS_VTIME_ACCOUNT
 void vtime_account(struct task_struct *tsk)
 {
-	unsigned long flags;
-
-	local_irq_save(flags);
-
 	if (in_interrupt() || !is_idle_task(tsk))
 		vtime_account_system(tsk);
 	else
 		vtime_account_idle(tsk);
-
-	local_irq_restore(flags);
 }
 EXPORT_SYMBOL_GPL(vtime_account);
 #endif /* __ARCH_HAS_VTIME_ACCOUNT */
-- 
1.7.5.4

[PATCH 5/5] vtime: Warn if irqs aren't disabled on system time accounting APIs

[Frederic Weisbecker]

System time accounting APIs such as vtime_account_system() and
vtime_account_idle() need to be irqsafe. Current callers include
irq entry, exit and kvm, all of which have been checked against that
requirement. Now it's better to grow that with an automatic check
in case we have further callers or we missed something.

Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
---
 arch/ia64/kernel/time.c    |    2 ++
 arch/powerpc/kernel/time.c |    2 ++
 arch/s390/kernel/vtime.c   |    2 ++
 3 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/arch/ia64/kernel/time.c b/arch/ia64/kernel/time.c
index c9a7d2e..b1995ef 100644
--- a/arch/ia64/kernel/time.c
+++ b/arch/ia64/kernel/time.c
@@ -119,6 +119,8 @@ static cputime_t vtime_delta(struct task_struct *tsk)
 	cputime_t delta_stime;
 	__u64 now;
 
+	WARN_ON_ONCE(!irqs_disabled());
+
 	now = ia64_get_itc();
 
 	delta_stime = cycle_to_cputime(ti->ac_stime + (now - ti->ac_stamp));
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 3486cfa..b3b1435 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -297,6 +297,8 @@ static u64 vtime_delta(struct task_struct *tsk,
 	u64 now, nowscaled, deltascaled;
 	u64 udelta, delta, user_scaled;
 
+	WARN_ON_ONCE(!irqs_disabled());
+
 	now = mftb();
 	nowscaled = read_spurr(now);
 	get_paca()->system_time += now - get_paca()->starttime;
diff --git a/arch/s390/kernel/vtime.c b/arch/s390/kernel/vtime.c
index 7c6d861..e84b8b6 100644
--- a/arch/s390/kernel/vtime.c
+++ b/arch/s390/kernel/vtime.c
@@ -132,6 +132,8 @@ void vtime_account(struct task_struct *tsk)
 	struct thread_info *ti = task_thread_info(tsk);
 	u64 timer, system;
 
+	WARN_ON_ONCE(!irqs_disabled());
+
 	timer = S390_lowcore.last_update_timer;
 	S390_lowcore.last_update_timer = get_vtimer();
 	S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;
-- 
1.7.5.4

Re: [GIT PULL] cputime: cleanups

[Ingo Molnar]

* Frederic Weisbecker <fweisbec@gmail.com> wrote:

> Ingo,
> 
> Please pull the latest sched cleanups branch that can be found at
> 
> git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git
> 	tags/sched-cputime-for-mingo
> 
> for you to pull the HEAD 1b2852b152be5150fbef7b585388ec43cf6f4415
> ("vtime: Warn if irqs aren't disabled on system time accounting APIs")
> 
> Thanks.
> 
> ---
> Some more cputime cleanups:
> 
> * Get rid of underscores polluting the vtime namespace
> 
> * Consolidate context switch and tick handling
> 
> * Improve debuggability by detecting irq unsafe callers
> 
> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
> ---
> 
> Frederic Weisbecker (5):
>   vtime: Remove the underscore prefix invasion
>   vtime: Explicitly account pending user time on process tick
>   vtime: Consolidate a bit the ctx switch code
>   vtime: No need to disable irqs on vtime_account()
>   vtime: Warn if irqs aren't disabled on system time accounting APIs
> 
>  arch/ia64/include/asm/cputime.h    |    2 ++
>  arch/ia64/kernel/time.c            |   26 ++++++--------------------
>  arch/powerpc/include/asm/cputime.h |    2 ++
>  arch/powerpc/kernel/time.c         |   24 ++++++++++--------------
>  arch/s390/include/asm/cputime.h    |    1 +
>  arch/s390/kernel/vtime.c           |   13 ++++++++++---
>  include/linux/kernel_stat.h        |    8 ++++++++
>  include/linux/kvm_host.h           |    4 ++--
>  include/linux/vtime.h              |    9 +++++----
>  kernel/sched/cputime.c             |   31 +++++++++++++++++++------------
>  10 files changed, 65 insertions(+), 55 deletions(-)

Pulled, thanks Frederic!

	Ingo