From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Wed, 13 Jul 2016 18:22:23 +0200
Subject: timer: make the base lock raw
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git
Git-commit: 100c98273a91b57f9bdc3393cb0a400e1c5f11c3
Patch-mainline: Queued in subsystem maintainer repository
References: SLE Realtime Extension

The part where the base lock is held got more predictable / shorter after the
timer rework. One reason is the lack of re-cascading.
That means the lock can be made raw and held in IRQ context.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Mike Galbraith <mgalbraith@suse.de>
---
 time/timer.c |   44 ++++++++++++++++++++++----------------------
 1 file changed, 22 insertions(+), 22 deletions(-)

--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -196,7 +196,7 @@
 #endif
 
 struct timer_base {
-	spinlock_t		lock;
+	raw_spinlock_t		lock;
 	struct timer_list	*running_timer;
 	unsigned long		clk;
 	unsigned long		next_expiry;
@@ -930,10 +930,10 @@
 
 		if (!(tf & TIMER_MIGRATING)) {
 			base = get_timer_base(tf);
-			spin_lock_irqsave(&base->lock, *flags);
+			raw_spin_lock_irqsave(&base->lock, *flags);
 			if (timer->flags == tf)
 				return base;
-			spin_unlock_irqrestore(&base->lock, *flags);
+			raw_spin_unlock_irqrestore(&base->lock, *flags);
 		}
 		cpu_relax();
 	}
@@ -1040,9 +1040,9 @@
 			/* See the comment in lock_timer_base() */
 			timer->flags |= TIMER_MIGRATING;
 
-			spin_unlock(&base->lock);
+			raw_spin_unlock(&base->lock);
 			base = new_base;
-			spin_lock(&base->lock);
+			raw_spin_lock(&base->lock);
 			WRITE_ONCE(timer->flags,
 				   (timer->flags & ~TIMER_BASEMASK) | base->cpu);
 			forward_timer_base(base);
@@ -1067,7 +1067,7 @@
 	}
 
 out_unlock:
-	spin_unlock_irqrestore(&base->lock, flags);
+	raw_spin_unlock_irqrestore(&base->lock, flags);
 
 	return ret;
 }
@@ -1207,9 +1207,9 @@
 	if (base != new_base) {
 		timer->flags |= TIMER_MIGRATING;
 
-		spin_unlock(&base->lock);
+		raw_spin_unlock(&base->lock);
 		base = new_base;
-		spin_lock(&base->lock);
+		raw_spin_lock(&base->lock);
 		WRITE_ONCE(timer->flags,
 			   (timer->flags & ~TIMER_BASEMASK) | cpu);
 	}
@@ -1218,7 +1218,7 @@
 	debug_activate(timer, timer->expires);
 	internal_add_timer(base, timer);
 out_unlock:
-	spin_unlock_irqrestore(&base->lock, flags);
+	raw_spin_unlock_irqrestore(&base->lock, flags);
 }
 EXPORT_SYMBOL_GPL(add_timer_on);
 
@@ -1602,13 +1602,13 @@
 		}
 
 		if (timer->flags & TIMER_IRQSAFE) {
-			spin_unlock(&base->lock);
+			raw_spin_unlock(&base->lock);
 			call_timer_fn(timer, fn, data);
-			spin_lock(&base->lock);
+			raw_spin_lock(&base->lock);
 		} else {
-			spin_unlock_irq(&base->lock);
+			raw_spin_unlock_irq(&base->lock);
 			call_timer_fn(timer, fn, data);
-			spin_lock_irq(&base->lock);
+			raw_spin_lock_irq(&base->lock);
 		}
 	}
 }
@@ -1777,7 +1777,7 @@
 	if (cpu_is_offline(smp_processor_id()))
 		return expires;
 
-	spin_lock(&base->lock);
+	raw_spin_lock(&base->lock);
 	nextevt = __next_timer_interrupt(base);
 	is_max_delta = (nextevt == base->clk + NEXT_TIMER_MAX_DELTA);
 	base->next_expiry = nextevt;
@@ -1811,7 +1811,7 @@
 			base->is_idle = true;
 		}
 	}
-	spin_unlock(&base->lock);
+	raw_spin_unlock(&base->lock);
 
 	return cmp_next_hrtimer_event(basem, expires);
 }
@@ -1906,7 +1906,7 @@
 	if (!time_after_eq(jiffies, base->clk))
 		return;
 
-	spin_lock_irq(&base->lock);
+	raw_spin_lock_irq(&base->lock);
 
 	/*
 	 * timer_base::must_forward_clk must be cleared before running
@@ -1933,7 +1933,7 @@
 			expire_timers(base, heads + levels);
 	}
 	base->running_timer = NULL;
-	spin_unlock_irq(&base->lock);
+	raw_spin_unlock_irq(&base->lock);
 }
 
 /*
@@ -2131,8 +2131,8 @@
 		 * The caller is globally serialized and nobody else
 		 * takes two locks at once, deadlock is not possible.
 		 */
-		spin_lock_irq(&new_base->lock);
-		spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
+		raw_spin_lock_irq(&new_base->lock);
+		raw_spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
 
 		/*
 		 * The current CPUs base clock might be stale. Update it
@@ -2146,8 +2146,8 @@
 		for (i = 0; i < WHEEL_SIZE; i++)
 			migrate_timer_list(new_base, old_base->vectors + i);
 
-		spin_unlock(&old_base->lock);
-		spin_unlock_irq(&new_base->lock);
+		raw_spin_unlock(&old_base->lock);
+		raw_spin_unlock_irq(&new_base->lock);
 		put_cpu_ptr(&timer_bases);
 	}
 	return 0;
@@ -2163,7 +2163,7 @@
 	for (i = 0; i < NR_BASES; i++) {
 		base = per_cpu_ptr(&timer_bases[i], cpu);
 		base->cpu = cpu;
-		spin_lock_init(&base->lock);
+		raw_spin_lock_init(&base->lock);
 		base->clk = jiffies;
 	}
 }