1 files changed, 44 insertions, 55 deletions

diff --git a/kernel/kernel/sched/cputime.c b/kernel/kernel/sched/cputime.c
index 0f75a38cf..558b98af2 100644
--- a/kernel/kernel/sched/cputime.c
+++ b/kernel/kernel/sched/cputime.c
@@ -259,21 +259,21 @@ static __always_inline bool steal_account_process_tick(void)
 #ifdef CONFIG_PARAVIRT
 	if (static_key_false(&paravirt_steal_enabled)) {
 		u64 steal;
-		cputime_t steal_ct;
+		unsigned long steal_jiffies;
 
 		steal = paravirt_steal_clock(smp_processor_id());
 		steal -= this_rq()->prev_steal_time;
 
 		/*
-		 * cputime_t may be less precise than nsecs (eg: if it's
-		 * based on jiffies). Lets cast the result to cputime
+		 * steal is in nsecs but our caller is expecting steal
+		 * time in jiffies. Lets cast the result to jiffies
 		 * granularity and account the rest on the next rounds.
 		 */
-		steal_ct = nsecs_to_cputime(steal);
-		this_rq()->prev_steal_time += cputime_to_nsecs(steal_ct);
+		steal_jiffies = nsecs_to_jiffies(steal);
+		this_rq()->prev_steal_time += jiffies_to_nsecs(steal_jiffies);
 
-		account_steal_time(steal_ct);
-		return steal_ct;
+		account_steal_time(jiffies_to_cputime(steal_jiffies));
+		return steal_jiffies;
 	}
 #endif
 	return false;
@@ -600,19 +600,25 @@ static void cputime_adjust(struct task_cputime *curr,
 	stime = curr->stime;
 	utime = curr->utime;
 
-	if (utime == 0) {
-		stime = rtime;
+	/*
+	 * If either stime or both stime and utime are 0, assume all runtime is
+	 * userspace. Once a task gets some ticks, the monotonicy code at
+	 * 'update' will ensure things converge to the observed ratio.
+	 */
+	if (stime == 0) {
+		utime = rtime;
 		goto update;
 	}
 
-	if (stime == 0) {
-		utime = rtime;
+	if (utime == 0) {
+		stime = rtime;
 		goto update;
 	}
 
 	stime = scale_stime((__force u64)stime, (__force u64)rtime,
 			    (__force u64)(stime + utime));
 
+update:
 	/*
 	 * Make sure stime doesn't go backwards; this preserves monotonicity
 	 * for utime because rtime is monotonic.
@@ -635,7 +641,6 @@ static void cputime_adjust(struct task_cputime *curr,
 		stime = rtime - utime;
 	}
 
-update:
 	prev->stime = stime;
 	prev->utime = utime;
 out:
@@ -680,7 +685,7 @@ static cputime_t get_vtime_delta(struct task_struct *tsk)
 {
 	unsigned long long delta = vtime_delta(tsk);
 
-	WARN_ON_ONCE(tsk->vtime_snap_whence == VTIME_SLEEPING);
+	WARN_ON_ONCE(tsk->vtime_snap_whence == VTIME_INACTIVE);
 	tsk->vtime_snap += delta;
 
 	/* CHECKME: always safe to convert nsecs to cputime? */
@@ -696,45 +701,37 @@ static void __vtime_account_system(struct task_struct *tsk)
 
 void vtime_account_system(struct task_struct *tsk)
 {
-	raw_spin_lock(&tsk->vtime_lock);
-	write_seqcount_begin(&tsk->vtime_seq);
+	write_seqcount_begin(&tsk->vtime_seqcount);
 	__vtime_account_system(tsk);
-	write_seqcount_end(&tsk->vtime_seq);
-	raw_spin_unlock(&tsk->vtime_lock);
+	write_seqcount_end(&tsk->vtime_seqcount);
 }
 
 void vtime_gen_account_irq_exit(struct task_struct *tsk)
 {
-	raw_spin_lock(&tsk->vtime_lock);
-	write_seqcount_begin(&tsk->vtime_seq);
+	write_seqcount_begin(&tsk->vtime_seqcount);
 	__vtime_account_system(tsk);
 	if (context_tracking_in_user())
 		tsk->vtime_snap_whence = VTIME_USER;
-	write_seqcount_end(&tsk->vtime_seq);
-	raw_spin_unlock(&tsk->vtime_lock);
+	write_seqcount_end(&tsk->vtime_seqcount);
 }
 
 void vtime_account_user(struct task_struct *tsk)
 {
 	cputime_t delta_cpu;
 
-	raw_spin_lock(&tsk->vtime_lock);
-	write_seqcount_begin(&tsk->vtime_seq);
+	write_seqcount_begin(&tsk->vtime_seqcount);
 	delta_cpu = get_vtime_delta(tsk);
 	tsk->vtime_snap_whence = VTIME_SYS;
 	account_user_time(tsk, delta_cpu, cputime_to_scaled(delta_cpu));
-	write_seqcount_end(&tsk->vtime_seq);
-	raw_spin_unlock(&tsk->vtime_lock);
+	write_seqcount_end(&tsk->vtime_seqcount);
 }
 
 void vtime_user_enter(struct task_struct *tsk)
 {
-	raw_spin_lock(&tsk->vtime_lock);
-	write_seqcount_begin(&tsk->vtime_seq);
+	write_seqcount_begin(&tsk->vtime_seqcount);
 	__vtime_account_system(tsk);
 	tsk->vtime_snap_whence = VTIME_USER;
-	write_seqcount_end(&tsk->vtime_seq);
-	raw_spin_unlock(&tsk->vtime_lock);
+	write_seqcount_end(&tsk->vtime_seqcount);
 }
 
 void vtime_guest_enter(struct task_struct *tsk)
@@ -746,23 +743,19 @@ void vtime_guest_enter(struct task_struct *tsk)
 	 * synchronization against the reader (task_gtime())
 	 * that can thus safely catch up with a tickless delta.
 	 */
-	raw_spin_lock(&tsk->vtime_lock);
-	write_seqcount_begin(&tsk->vtime_seq);
+	write_seqcount_begin(&tsk->vtime_seqcount);
 	__vtime_account_system(tsk);
 	current->flags |= PF_VCPU;
-	write_seqcount_end(&tsk->vtime_seq);
-	raw_spin_unlock(&tsk->vtime_lock);
+	write_seqcount_end(&tsk->vtime_seqcount);
 }
 EXPORT_SYMBOL_GPL(vtime_guest_enter);
 
 void vtime_guest_exit(struct task_struct *tsk)
 {
-	raw_spin_lock(&tsk->vtime_lock);
-	write_seqcount_begin(&tsk->vtime_seq);
+	write_seqcount_begin(&tsk->vtime_seqcount);
 	__vtime_account_system(tsk);
 	current->flags &= ~PF_VCPU;
-	write_seqcount_end(&tsk->vtime_seq);
-	raw_spin_unlock(&tsk->vtime_lock);
+	write_seqcount_end(&tsk->vtime_seqcount);
 }
 EXPORT_SYMBOL_GPL(vtime_guest_exit);
 
@@ -775,30 +768,26 @@ void vtime_account_idle(struct task_struct *tsk)
 
 void arch_vtime_task_switch(struct task_struct *prev)
 {
-	raw_spin_lock(&prev->vtime_lock);
-	write_seqcount_begin(&prev->vtime_seq);
-	prev->vtime_snap_whence = VTIME_SLEEPING;
-	write_seqcount_end(&prev->vtime_seq);
-	raw_spin_unlock(&prev->vtime_lock);
+	write_seqcount_begin(&prev->vtime_seqcount);
+	prev->vtime_snap_whence = VTIME_INACTIVE;
+	write_seqcount_end(&prev->vtime_seqcount);
 
-	raw_spin_lock(&current->vtime_lock);
-	write_seqcount_begin(&current->vtime_seq);
+	write_seqcount_begin(&current->vtime_seqcount);
 	current->vtime_snap_whence = VTIME_SYS;
 	current->vtime_snap = sched_clock_cpu(smp_processor_id());
-	write_seqcount_end(&current->vtime_seq);
-	raw_spin_unlock(&current->vtime_lock);
+	write_seqcount_end(&current->vtime_seqcount);
 }
 
 void vtime_init_idle(struct task_struct *t, int cpu)
 {
 	unsigned long flags;
 
-	raw_spin_lock_irqsave(&t->vtime_lock, flags);
-	write_seqcount_begin(&t->vtime_seq);
+	local_irq_save(flags);
+	write_seqcount_begin(&t->vtime_seqcount);
 	t->vtime_snap_whence = VTIME_SYS;
 	t->vtime_snap = sched_clock_cpu(cpu);
-	write_seqcount_end(&t->vtime_seq);
-	raw_spin_unlock_irqrestore(&t->vtime_lock, flags);
+	write_seqcount_end(&t->vtime_seqcount);
+	local_irq_restore(flags);
 }
 
 cputime_t task_gtime(struct task_struct *t)
@@ -810,13 +799,13 @@ cputime_t task_gtime(struct task_struct *t)
 		return t->gtime;
 
 	do {
-		seq = read_seqcount_begin(&t->vtime_seq);
+		seq = read_seqcount_begin(&t->vtime_seqcount);
 
 		gtime = t->gtime;
 		if (t->flags & PF_VCPU)
 			gtime += vtime_delta(t);
 
-	} while (read_seqcount_retry(&t->vtime_seq, seq));
+	} while (read_seqcount_retry(&t->vtime_seqcount, seq));
 
 	return gtime;
 }
@@ -839,7 +828,7 @@ fetch_task_cputime(struct task_struct *t,
 		*udelta = 0;
 		*sdelta = 0;
 
-		seq = read_seqcount_begin(&t->vtime_seq);
+		seq = read_seqcount_begin(&t->vtime_seqcount);
 
 		if (u_dst)
 			*u_dst = *u_src;
@@ -847,7 +836,7 @@ fetch_task_cputime(struct task_struct *t,
 			*s_dst = *s_src;
 
 		/* Task is sleeping, nothing to add */
-		if (t->vtime_snap_whence == VTIME_SLEEPING ||
+		if (t->vtime_snap_whence == VTIME_INACTIVE ||
 		    is_idle_task(t))
 			continue;
 
@@ -863,7 +852,7 @@ fetch_task_cputime(struct task_struct *t,
 			if (t->vtime_snap_whence == VTIME_SYS)
 				*sdelta = delta;
 		}
-	} while (read_seqcount_retry(&t->vtime_seq, seq));
+	} while (read_seqcount_retry(&t->vtime_seqcount, seq));
 }