From: Prarit Bhargava <prarit@redhat.com>
Date: Thu, 29 Jan 2009 08:28:39 -0500
Subject: [misc] fix leap second hang
Message-id: 4981AF07.8050005@redhat.com
O-Subject: Re: [RHEL5 PATCH]: Fix leap second hang
Bugzilla: 479765
RH-Acked-by: Michal Schmidt <mschmidt@redhat.com>
RH-Acked-by: Ivan Vecera <ivecera@redhat.com>
RH-Acked-by: Rik van Riel <riel@redhat.com>
RH-Acked-by: Aristeu Rozanski <aris@redhat.com>

During the leap second between 2008-2009 it was noticed that RHEL servers
were hanging.

Backport of http://lkml.org/lkml/2009/1/2/415.  However, our codebase is
significantly different from upstream so I've implemented a
leap_second_message() function that is available to all arches.

Brew build: http://brewweb.devel.redhat.com/brew/taskinfo?taskID=1666146

Successfully tested by me.

P.

diff --git a/arch/i386/kernel/time.c b/arch/i386/kernel/time.c
index 7ebde24..82fdd13 100644
--- a/arch/i386/kernel/time.c
+++ b/arch/i386/kernel/time.c
@@ -199,6 +199,8 @@ irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
 		smp_send_timer_broadcast_ipi(regs);
 #endif
 
+	leap_second_message();
+
 	return IRQ_HANDLED;
 }
 
diff --git a/arch/ia64/kernel/time.c b/arch/ia64/kernel/time.c
index e036828..429e1a9 100644
--- a/arch/ia64/kernel/time.c
+++ b/arch/ia64/kernel/time.c
@@ -133,6 +133,7 @@ consider_steal_time(unsigned long new_itm, struct pt_regs *regs)
 				do_timer(regs);
 			local_cpu_data->itm_next = delta_itm + new_itm;
 			write_sequnlock(&xtime_lock);
+			leap_second_message();
 		} else {
 			local_cpu_data->itm_next = delta_itm + new_itm;
 		}
@@ -188,6 +189,7 @@ timer_interrupt (int irq, void *dev_id, struct pt_regs *regs)
 			do_timer(regs);
 			local_cpu_data->itm_next = new_itm;
 			write_sequnlock(&xtime_lock);
+			leap_second_message();
 		} else
 			local_cpu_data->itm_next = new_itm;
 
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 310f23f..ba9a535 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -669,6 +669,7 @@ void timer_interrupt(struct pt_regs * regs)
 			timer_check_rtc();
 		}
 		write_sequnlock(&xtime_lock);
+		leap_second_message();
 	}
 	
 	next_dec = tb_ticks_per_jiffy - ticks;
diff --git a/arch/ppc/kernel/time.c b/arch/ppc/kernel/time.c
index f4f3789..59cb7e5 100644
--- a/arch/ppc/kernel/time.c
+++ b/arch/ppc/kernel/time.c
@@ -182,6 +182,7 @@ void timer_interrupt(struct pt_regs * regs)
 				last_rtc_update += 60;
 		}
 		write_sequnlock(&xtime_lock);
+		leap_second_message();
 	}
 	if ( !disarm_decr[smp_processor_id()] )
 		set_dec(next_dec);
diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index 812886e..f767bdd 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -220,6 +220,7 @@ void account_ticks(struct pt_regs *regs)
 	for (xticks = ticks; xticks > 0; xticks--)
 		do_timer(regs);
 #endif
+	leap_second_message();
 
 #ifdef CONFIG_VIRT_CPU_ACCOUNTING
 	account_tick_vtime(current);
diff --git a/arch/x86_64/kernel/time.c b/arch/x86_64/kernel/time.c
index fa1985f..9635380 100644
--- a/arch/x86_64/kernel/time.c
+++ b/arch/x86_64/kernel/time.c
@@ -487,6 +487,8 @@ void main_timer_handler(struct pt_regs *regs)
 	}
  
 	write_sequnlock(&xtime_lock);
+
+	leap_second_message();
 }
 
 static irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
diff --git a/include/linux/timex.h b/include/linux/timex.h
index d543d38..ab71c9a 100644
--- a/include/linux/timex.h
+++ b/include/linux/timex.h
@@ -311,6 +311,29 @@ extern u64 current_tick_length(void);
 
 extern int do_adjtimex(struct timex *);
 
+/* Code based on patch from http://lkml.org/lkml/2009/1/2/415.
+   RHEL5 code base is significantly different from upstream so we have to
+   resort to this ... */
+
+extern unsigned long leap_second;
+
+static inline void leap_second_message(void)
+{
+	if (unlikely(leap_second != TIME_OK)) {
+		switch (leap_second) {
+		case TIME_INS:
+			printk(KERN_NOTICE "Clock: inserting leap second "
+					"23:59:60 UTC\n");
+			break;
+		case TIME_DEL:
+			printk(KERN_NOTICE "Clock: deleting leap second "
+					"23:59:59 UTC\n");
+			break;
+		}
+		leap_second = TIME_OK;
+	}
+}
+
 #endif /* KERNEL */
 
 #endif /* LINUX_TIMEX_H */
diff --git a/kernel/timer.c b/kernel/timer.c
index bafef95..0e831b5 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -34,6 +34,7 @@
 #include <linux/cpu.h>
 #include <linux/syscalls.h>
 #include <linux/delay.h>
+#include <linux/timex.h>
 
 #include <asm/uaccess.h>
 #include <asm/unistd.h>
@@ -740,6 +741,8 @@ long time_reftime;			/* time at last adjustment (s)	*/
 long time_adjust;
 long time_next_adjust;
 
+unsigned long leap_second = TIME_OK;
+
 /*
  * this routine handles the overflow of the microsecond field
  *
@@ -785,8 +788,7 @@ static void second_overflow(void)
 			time_interpolator_update(-NSEC_PER_SEC);
 			time_state = TIME_OOP;
 			clock_was_set();
-			printk(KERN_NOTICE "Clock: inserting leap second "
-					"23:59:60 UTC\n");
+			leap_second = TIME_INS;
 		}
 		break;
 	case TIME_DEL:
@@ -800,8 +802,7 @@ static void second_overflow(void)
 			time_interpolator_update(NSEC_PER_SEC);
 			time_state = TIME_WAIT;
 			clock_was_set();
-			printk(KERN_NOTICE "Clock: deleting leap second "
-					"23:59:59 UTC\n");
+			leap_second = TIME_DEL;
 		}
 		break;
 	case TIME_OOP: