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authorThomas Gleixner <tglx@linutronix.de>2017-12-27 21:37:25 +0100
committerThomas Gleixner <tglx@linutronix.de>2017-12-29 23:13:09 +0100
commit26456f87aca7157c057de65c9414b37f1ab881d1 (patch)
treefd5e08429f5b554a8403aea730495654eaa4a23f
parentced6d5c11d3e7b342f1a80f908e6756ebd4b8ddd (diff)
downloadlinux-26456f87aca7157c057de65c9414b37f1ab881d1.tar.bz2
timers: Reinitialize per cpu bases on hotplug
The timer wheel bases are not (re)initialized on CPU hotplug. That leaves them with a potentially stale clk and next_expiry valuem, which can cause trouble then the CPU is plugged. Add a prepare callback which forwards the clock, sets next_expiry to far in the future and reset the control flags to a known state. Set base->must_forward_clk so the first timer which is queued will try to forward the clock to current jiffies. Fixes: 500462a9de65 ("timers: Switch to a non-cascading wheel") Reported-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Anna-Maria Gleixner <anna-maria@linutronix.de> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/alpine.DEB.2.20.1712272152200.2431@nanos
-rw-r--r--include/linux/cpuhotplug.h2
-rw-r--r--include/linux/timer.h4
-rw-r--r--kernel/cpu.c4
-rw-r--r--kernel/time/timer.c15
4 files changed, 21 insertions, 4 deletions
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 201ab7267986..1a32e558eb11 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -86,7 +86,7 @@ enum cpuhp_state {
CPUHP_MM_ZSWP_POOL_PREPARE,
CPUHP_KVM_PPC_BOOK3S_PREPARE,
CPUHP_ZCOMP_PREPARE,
- CPUHP_TIMERS_DEAD,
+ CPUHP_TIMERS_PREPARE,
CPUHP_MIPS_SOC_PREPARE,
CPUHP_BP_PREPARE_DYN,
CPUHP_BP_PREPARE_DYN_END = CPUHP_BP_PREPARE_DYN + 20,
diff --git a/include/linux/timer.h b/include/linux/timer.h
index 04af640ea95b..2448f9cc48a3 100644
--- a/include/linux/timer.h
+++ b/include/linux/timer.h
@@ -207,9 +207,11 @@ unsigned long round_jiffies_up(unsigned long j);
unsigned long round_jiffies_up_relative(unsigned long j);
#ifdef CONFIG_HOTPLUG_CPU
+int timers_prepare_cpu(unsigned int cpu);
int timers_dead_cpu(unsigned int cpu);
#else
-#define timers_dead_cpu NULL
+#define timers_prepare_cpu NULL
+#define timers_dead_cpu NULL
#endif
#endif
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 41376c3ac93b..97858477e586 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -1277,9 +1277,9 @@ static struct cpuhp_step cpuhp_bp_states[] = {
* before blk_mq_queue_reinit_notify() from notify_dead(),
* otherwise a RCU stall occurs.
*/
- [CPUHP_TIMERS_DEAD] = {
+ [CPUHP_TIMERS_PREPARE] = {
.name = "timers:dead",
- .startup.single = NULL,
+ .startup.single = timers_prepare_cpu,
.teardown.single = timers_dead_cpu,
},
/* Kicks the plugged cpu into life */
diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 19a9c3da7698..6be576e02209 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -1853,6 +1853,21 @@ static void migrate_timer_list(struct timer_base *new_base, struct hlist_head *h
}
}
+int timers_prepare_cpu(unsigned int cpu)
+{
+ struct timer_base *base;
+ int b;
+
+ for (b = 0; b < NR_BASES; b++) {
+ base = per_cpu_ptr(&timer_bases[b], cpu);
+ base->clk = jiffies;
+ base->next_expiry = base->clk + NEXT_TIMER_MAX_DELTA;
+ base->is_idle = false;
+ base->must_forward_clk = true;
+ }
+ return 0;
+}
+
int timers_dead_cpu(unsigned int cpu)
{
struct timer_base *old_base;