Merge tag 'timers-core-2024-01-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull timer subsystem updates from Ingo Molnar:

 - Various preparatory cleanups & enhancements of the timer-wheel code,
   in preparation for the WIP 'pull timers at expiry' timer migration
   model series (which will replace the current 'push timers at enqueue'
   migration model), by Anna-Maria Behnsen:

      - Update comments and clean up confusing variable names

      - Add debug check to warn about time travel

      - Improve/expand timer-wheel tracepoints

      - Optimize away unnecessary IPIs for deferrable timers

      - Restructure & clean up next_expiry_recalc()

      - Clean up forward_timer_base()

      - Introduce __forward_timer_base() and use it to simplify and
        micro-optimize get_next_timer_interrupt()

 - Restructure the get_next_timer_interrupt()'s idle logic for better
   readability and to enable a minor optimization.

 - Fix the nextevt calculation when no timers are pending

 - Fix the sysfs_get_uname() prototype declaration

* tag 'timers-core-2024-01-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  timers: Fix nextevt calculation when no timers are pending
  timers: Rework idle logic
  timers: Use already existing function for forwarding timer base
  timers: Split out forward timer base functionality
  timers: Clarify check in forward_timer_base()
  timers: Move store of next event into __next_timer_interrupt()
  timers: Do not IPI for deferrable timers
  tracing/timers: Add tracepoint for tracking timer base is_idle flag
  tracing/timers: Enhance timer_start tracepoint
  tick-sched: Warn when next tick seems to be in the past
  tick/sched: Cleanup confusing variables
  tick-sched: Fix function names in comments
  time: Make sysfs_get_uname() function visible in header

1 files changed, 30 insertions, 10 deletions

diff --git a/include/trace/events/timer.h b/include/trace/events/timer.h
index b4bc2828fa09..1ef58a04fc57 100644
--- a/include/trace/events/timer.h
+++ b/include/trace/events/timer.h
@@ -46,22 +46,21 @@ DEFINE_EVENT(timer_class, timer_init,
 
 /**
  * timer_start - called when the timer is started
- * @timer:	pointer to struct timer_list
- * @expires:	the timers expiry time
- * @flags:	the timers flags
+ * @timer:		pointer to struct timer_list
+ * @bucket_expiry:	the bucket expiry time
  */
 TRACE_EVENT(timer_start,
 
 	TP_PROTO(struct timer_list *timer,
-		unsigned long expires,
-		unsigned int flags),
+		unsigned long bucket_expiry),
 
-	TP_ARGS(timer, expires, flags),
+	TP_ARGS(timer, bucket_expiry),
 
 	TP_STRUCT__entry(
 		__field( void *,	timer		)
 		__field( void *,	function	)
 		__field( unsigned long,	expires		)
+		__field( unsigned long,	bucket_expiry	)
 		__field( unsigned long,	now		)
 		__field( unsigned int,	flags		)
 	),
@@ -69,15 +68,16 @@ TRACE_EVENT(timer_start,
 	TP_fast_assign(
 		__entry->timer		= timer;
 		__entry->function	= timer->function;
-		__entry->expires	= expires;
+		__entry->expires	= timer->expires;
+		__entry->bucket_expiry	= bucket_expiry;
 		__entry->now		= jiffies;
-		__entry->flags		= flags;
+		__entry->flags		= timer->flags;
 	),
 
-	TP_printk("timer=%p function=%ps expires=%lu [timeout=%ld] cpu=%u idx=%u flags=%s",
+	TP_printk("timer=%p function=%ps expires=%lu [timeout=%ld] bucket_expiry=%lu cpu=%u idx=%u flags=%s",
 		  __entry->timer, __entry->function, __entry->expires,
 		  (long)__entry->expires - __entry->now,
-		  __entry->flags & TIMER_CPUMASK,
+		  __entry->bucket_expiry, __entry->flags & TIMER_CPUMASK,
 		  __entry->flags >> TIMER_ARRAYSHIFT,
 		  decode_timer_flags(__entry->flags & TIMER_TRACE_FLAGMASK))
 );
@@ -142,6 +142,26 @@ DEFINE_EVENT(timer_class, timer_cancel,
 	TP_ARGS(timer)
 );
 
+TRACE_EVENT(timer_base_idle,
+
+	TP_PROTO(bool is_idle, unsigned int cpu),
+
+	TP_ARGS(is_idle, cpu),
+
+	TP_STRUCT__entry(
+		__field( bool,		is_idle	)
+		__field( unsigned int,	cpu	)
+	),
+
+	TP_fast_assign(
+		__entry->is_idle	= is_idle;
+		__entry->cpu		= cpu;
+	),
+
+	TP_printk("is_idle=%d cpu=%d",
+		  __entry->is_idle, __entry->cpu)
+);
+
 #define decode_clockid(type)						\
 	__print_symbolic(type,						\
 		{ CLOCK_REALTIME,	"CLOCK_REALTIME"	},	\