Subject: softirq: Use sched_clock() based timeout
From: Peter Zijlstra <peterz@infradead.org>
Date: Fri Sep 11 17:30:01 CEST 2020

Replace the jiffies based timeout with a sched_clock() based one.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 kernel/softirq.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -25,6 +25,7 @@
 #include <linux/smpboot.h>
 #include <linux/tick.h>
 #include <linux/irq.h>
+#include <linux/sched/clock.h>
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/irq.h>
@@ -216,7 +217,7 @@ EXPORT_SYMBOL(__local_bh_enable_ip);
  * we want to handle softirqs as soon as possible, but they
  * should not be able to lock up the box.
  */
-#define MAX_SOFTIRQ_TIME  msecs_to_jiffies(2)
+#define MAX_SOFTIRQ_TIME	2*NSEC_PER_MSEC
 #define MAX_SOFTIRQ_RESTART 10
 
 #ifdef CONFIG_TRACE_IRQFLAGS
@@ -254,9 +255,9 @@ static inline void lockdep_softirq_end(b
 
 asmlinkage __visible void __softirq_entry __do_softirq(void)
 {
-	unsigned long end = jiffies + MAX_SOFTIRQ_TIME;
 	unsigned long old_flags = current->flags;
 	int max_restart = MAX_SOFTIRQ_RESTART;
+	u64 start = sched_clock();
 	struct softirq_action *h;
 	unsigned long pending;
 	unsigned int vec_nr;
@@ -309,7 +310,7 @@ asmlinkage __visible void __softirq_entr
 
 	pending = local_softirq_pending();
 	if (pending) {
-		if (time_before(jiffies, end) && !need_resched() &&
+		if (sched_clock() - start < MAX_SOFTIRQ_TIME && !need_resched() &&
 		    --max_restart)
 			goto restart;