[RFC PATCH 2/2] s390/vtime: Remove vtimer infrastructure

[Heiko Carstens <hca@linux.ibm.com>]

The only user is gone - remove the vtimer infrastructure.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
---
 arch/s390/include/asm/vtime.h  |   2 +
 arch/s390/include/asm/vtimer.h |  30 -----
 arch/s390/kernel/process.c     |   1 -
 arch/s390/kernel/smp.c         |   2 +-
 arch/s390/kernel/time.c        |   2 +-
 arch/s390/kernel/vtime.c       | 212 ++-------------------------------
 6 files changed, 12 insertions(+), 237 deletions(-)
 delete mode 100644 arch/s390/include/asm/vtimer.h

diff --git a/arch/s390/include/asm/vtime.h b/arch/s390/include/asm/vtime.h
index da116a93d3b6..22e494b22192 100644
--- a/arch/s390/include/asm/vtime.h
+++ b/arch/s390/include/asm/vtime.h
@@ -8,6 +8,8 @@
 
 DECLARE_PER_CPU(u64, mt_cycles[8]);
 
+void vtime_init(void);
+
 static inline void update_timer_sys(void)
 {
 	struct lowcore *lc = get_lowcore();
diff --git a/arch/s390/include/asm/vtimer.h b/arch/s390/include/asm/vtimer.h
deleted file mode 100644
index e601adaa6320..000000000000
--- a/arch/s390/include/asm/vtimer.h
+++ /dev/null
@@ -1,30 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-/*
- *  Copyright IBM Corp. 2003, 2012
- *  Virtual CPU timer
- *
- *  Author(s): Jan Glauber <jan.glauber@de.ibm.com>
- */
-
-#ifndef _ASM_S390_TIMER_H
-#define _ASM_S390_TIMER_H
-
-#define VTIMER_MAX_SLICE (0x7fffffffffffffffULL)
-
-struct vtimer_list {
-	struct list_head entry;
-	u64 expires;
-	u64 interval;
-	void (*function)(unsigned long);
-	unsigned long data;
-};
-
-extern void init_virt_timer(struct vtimer_list *timer);
-extern void add_virt_timer(struct vtimer_list *timer);
-extern void add_virt_timer_periodic(struct vtimer_list *timer);
-extern int mod_virt_timer(struct vtimer_list *timer, u64 expires);
-extern int mod_virt_timer_periodic(struct vtimer_list *timer, u64 expires);
-extern int del_virt_timer(struct vtimer_list *timer);
-extern void vtime_init(void);
-
-#endif /* _ASM_S390_TIMER_H */
diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c
index 416650ae4871..4c73d2528fcb 100644
--- a/arch/s390/kernel/process.c
+++ b/arch/s390/kernel/process.c
@@ -35,7 +35,6 @@
 #include <asm/cpu_mf.h>
 #include <asm/processor.h>
 #include <asm/ptrace.h>
-#include <asm/vtimer.h>
 #include <asm/exec.h>
 #include <asm/fpu.h>
 #include <asm/irq.h>
diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index 32499cad86f0..f7c262a17c03 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -48,7 +48,7 @@
 #include <asm/setup.h>
 #include <asm/irq.h>
 #include <asm/tlbflush.h>
-#include <asm/vtimer.h>
+#include <asm/vtime.h>
 #include <asm/abs_lowcore.h>
 #include <asm/sclp.h>
 #include <asm/debug.h>
diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index 2b989bebd220..dd8a88cc9c4b 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -48,9 +48,9 @@
 #include <asm/vdso.h>
 #include <asm/irq.h>
 #include <asm/irq_regs.h>
-#include <asm/vtimer.h>
 #include <asm/stp.h>
 #include <asm/cio.h>
+#include <asm/vtime.h>
 #include "entry.h"
 
 union tod_clock __bootdata_preserved(tod_clock_base);
diff --git a/arch/s390/kernel/vtime.c b/arch/s390/kernel/vtime.c
index efcbf406f03e..d9fd39c5732e 100644
--- a/arch/s390/kernel/vtime.c
+++ b/arch/s390/kernel/vtime.c
@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 /*
- *    Virtual cpu timer based timer functions.
+ *    Virtual CPU time accounting
  *
  *    Copyright IBM Corp. 2004, 2012
  *    Author(s): Jan Glauber <jan.glauber@de.ibm.com>
@@ -14,7 +14,6 @@
 #include <linux/time.h>
 #include <asm/alternative.h>
 #include <asm/cputime.h>
-#include <asm/vtimer.h>
 #include <asm/vtime.h>
 #include <asm/cpu_mf.h>
 #include <asm/idle.h>
@@ -22,19 +21,14 @@
 
 #include "entry.h"
 
-static void virt_timer_expire(void);
-
-static LIST_HEAD(virt_timer_list);
-static DEFINE_SPINLOCK(virt_timer_lock);
-static atomic64_t virt_timer_current;
-static atomic64_t virt_timer_elapsed;
+#define CPU_TIMER_MAX	0x7fffffffffffffffUL
 
 DEFINE_PER_CPU(u64, mt_cycles[8]);
 static DEFINE_PER_CPU(u64, mt_scaling_mult) = { 1 };
 static DEFINE_PER_CPU(u64, mt_scaling_div) = { 1 };
 static DEFINE_PER_CPU(unsigned long, mt_scaling_jiffies);
 
-static inline void set_vtimer(u64 expires)
+static inline void cpu_timer_init(u64 value)
 {
 	struct lowcore *lc = get_lowcore();
 	u64 timer;
@@ -42,18 +36,9 @@ static inline void set_vtimer(u64 expires)
 	asm volatile(
 		"	stpt	%0\n"	/* Store current cpu timer value */
 		"	spt	%1"	/* Set new value imm. afterwards */
-		: "=Q" (timer) : "Q" (expires));
+		: "=Q" (timer) : "Q" (value));
 	lc->system_timer += lc->last_update_timer - timer;
-	lc->last_update_timer = expires;
-}
-
-static inline int virt_timer_forward(u64 elapsed)
-{
-	lockdep_assert_irqs_disabled();
-	if (list_empty(&virt_timer_list))
-		return 0;
-	elapsed = atomic64_add_return(elapsed, &virt_timer_elapsed);
-	return elapsed >= atomic64_read(&virt_timer_current);
+	lc->last_update_timer = value;
 }
 
 static void update_mt_scaling(void)
@@ -125,7 +110,7 @@ static inline void vtime_reset_last_update(struct lowcore *lc)
  * Update process times based on virtual cpu times stored by entry.S
  * to the lowcore fields user_timer, system_timer & steal_clock.
  */
-static int do_account_vtime(struct task_struct *tsk)
+static void do_account_vtime(struct task_struct *tsk)
 {
 	u64 timer, clock, user, guest, system, hardirq, softirq;
 	struct lowcore *lc = get_lowcore();
@@ -172,8 +157,6 @@ static int do_account_vtime(struct task_struct *tsk)
 		account_system_index_scaled(tsk, hardirq, CPUTIME_IRQ);
 	if (softirq)
 		account_system_index_scaled(tsk, softirq, CPUTIME_SOFTIRQ);
-
-	return virt_timer_forward(user + guest + system + hardirq + softirq);
 }
 
 void vtime_task_switch(struct task_struct *prev)
@@ -203,8 +186,7 @@ void vtime_flush(struct task_struct *tsk)
 	struct lowcore *lc = get_lowcore();
 	u64 steal, avg_steal;
 
-	if (do_account_vtime(tsk))
-		virt_timer_expire();
+	do_account_vtime(tsk);
 
 	steal = lc->steal_timer;
 	avg_steal = lc->avg_steal_timer;
@@ -247,187 +229,9 @@ void vtime_account_hardirq(struct task_struct *tsk)
 	get_lowcore()->hardirq_timer += vtime_delta();
 }
 
-/*
- * Sorted add to a list. List is linear searched until first bigger
- * element is found.
- */
-static void list_add_sorted(struct vtimer_list *timer, struct list_head *head)
-{
-	struct vtimer_list *tmp;
-
-	list_for_each_entry(tmp, head, entry) {
-		if (tmp->expires > timer->expires) {
-			list_add_tail(&timer->entry, &tmp->entry);
-			return;
-		}
-	}
-	list_add_tail(&timer->entry, head);
-}
-
-/*
- * Handler for expired virtual CPU timer.
- */
-static void virt_timer_expire(void)
-{
-	struct vtimer_list *timer, *tmp;
-	unsigned long elapsed;
-	LIST_HEAD(cb_list);
-
-	/* walk timer list, fire all expired timers */
-	spin_lock(&virt_timer_lock);
-	elapsed = atomic64_read(&virt_timer_elapsed);
-	list_for_each_entry_safe(timer, tmp, &virt_timer_list, entry) {
-		if (timer->expires < elapsed)
-			/* move expired timer to the callback queue */
-			list_move_tail(&timer->entry, &cb_list);
-		else
-			timer->expires -= elapsed;
-	}
-	if (!list_empty(&virt_timer_list)) {
-		timer = list_first_entry(&virt_timer_list,
-					 struct vtimer_list, entry);
-		atomic64_set(&virt_timer_current, timer->expires);
-	}
-	atomic64_sub(elapsed, &virt_timer_elapsed);
-	spin_unlock(&virt_timer_lock);
-
-	/* Do callbacks and recharge periodic timers */
-	list_for_each_entry_safe(timer, tmp, &cb_list, entry) {
-		list_del_init(&timer->entry);
-		timer->function(timer->data);
-		if (timer->interval) {
-			/* Recharge interval timer */
-			timer->expires = timer->interval +
-				atomic64_read(&virt_timer_elapsed);
-			spin_lock(&virt_timer_lock);
-			list_add_sorted(timer, &virt_timer_list);
-			spin_unlock(&virt_timer_lock);
-		}
-	}
-}
-
-void init_virt_timer(struct vtimer_list *timer)
-{
-	timer->function = NULL;
-	INIT_LIST_HEAD(&timer->entry);
-}
-EXPORT_SYMBOL(init_virt_timer);
-
-static inline int vtimer_pending(struct vtimer_list *timer)
-{
-	return !list_empty(&timer->entry);
-}
-
-static void internal_add_vtimer(struct vtimer_list *timer)
-{
-	if (list_empty(&virt_timer_list)) {
-		/* First timer, just program it. */
-		atomic64_set(&virt_timer_current, timer->expires);
-		atomic64_set(&virt_timer_elapsed, 0);
-		list_add(&timer->entry, &virt_timer_list);
-	} else {
-		/* Update timer against current base. */
-		timer->expires += atomic64_read(&virt_timer_elapsed);
-		if (likely((s64) timer->expires <
-			   (s64) atomic64_read(&virt_timer_current)))
-			/* The new timer expires before the current timer. */
-			atomic64_set(&virt_timer_current, timer->expires);
-		/* Insert new timer into the list. */
-		list_add_sorted(timer, &virt_timer_list);
-	}
-}
-
-static void __add_vtimer(struct vtimer_list *timer, int periodic)
-{
-	unsigned long flags;
-
-	timer->interval = periodic ? timer->expires : 0;
-	spin_lock_irqsave(&virt_timer_lock, flags);
-	internal_add_vtimer(timer);
-	spin_unlock_irqrestore(&virt_timer_lock, flags);
-}
-
-/*
- * add_virt_timer - add a oneshot virtual CPU timer
- */
-void add_virt_timer(struct vtimer_list *timer)
-{
-	__add_vtimer(timer, 0);
-}
-EXPORT_SYMBOL(add_virt_timer);
-
-/*
- * add_virt_timer_int - add an interval virtual CPU timer
- */
-void add_virt_timer_periodic(struct vtimer_list *timer)
-{
-	__add_vtimer(timer, 1);
-}
-EXPORT_SYMBOL(add_virt_timer_periodic);
-
-static int __mod_vtimer(struct vtimer_list *timer, u64 expires, int periodic)
-{
-	unsigned long flags;
-	int rc;
-
-	BUG_ON(!timer->function);
-
-	if (timer->expires == expires && vtimer_pending(timer))
-		return 1;
-	spin_lock_irqsave(&virt_timer_lock, flags);
-	rc = vtimer_pending(timer);
-	if (rc)
-		list_del_init(&timer->entry);
-	timer->interval = periodic ? expires : 0;
-	timer->expires = expires;
-	internal_add_vtimer(timer);
-	spin_unlock_irqrestore(&virt_timer_lock, flags);
-	return rc;
-}
-
-/*
- * returns whether it has modified a pending timer (1) or not (0)
- */
-int mod_virt_timer(struct vtimer_list *timer, u64 expires)
-{
-	return __mod_vtimer(timer, expires, 0);
-}
-EXPORT_SYMBOL(mod_virt_timer);
-
-/*
- * returns whether it has modified a pending timer (1) or not (0)
- */
-int mod_virt_timer_periodic(struct vtimer_list *timer, u64 expires)
-{
-	return __mod_vtimer(timer, expires, 1);
-}
-EXPORT_SYMBOL(mod_virt_timer_periodic);
-
-/*
- * Delete a virtual timer.
- *
- * returns whether the deleted timer was pending (1) or not (0)
- */
-int del_virt_timer(struct vtimer_list *timer)
-{
-	unsigned long flags;
-
-	if (!vtimer_pending(timer))
-		return 0;
-	spin_lock_irqsave(&virt_timer_lock, flags);
-	list_del_init(&timer->entry);
-	spin_unlock_irqrestore(&virt_timer_lock, flags);
-	return 1;
-}
-EXPORT_SYMBOL(del_virt_timer);
-
-/*
- * Start the virtual CPU timer on the current CPU.
- */
 void vtime_init(void)
 {
-	/* set initial cpu timer */
-	set_vtimer(VTIMER_MAX_SLICE);
+	cpu_timer_init(CPU_TIMER_MAX);
 	/* Setup initial MT scaling values */
 	if (smp_cpu_mtid) {
 		__this_cpu_write(mt_scaling_jiffies, jiffies);
-- 
2.53.0