[Xen-devel] [PATCH] linux/x86: fix long timeout handling in stop_hz_timer()

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

Other than for HYPERVISOR_set_timer_op, zero doesn't mean "no timeout"
for VCPUOP_set_singleshot_timer (but should be retained rather than
adjusted by NS_PER_TICK/2 for the former).

Also properly cancel the singleshot timer is start_hz_timer().

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>

--- a/arch/i386/kernel/time-xen.c
+++ b/arch/i386/kernel/time-xen.c
@@ -939,7 +939,10 @@ static void stop_hz_timer(void)
                j = jiffies + 1;
        }
 
-       singleshot.timeout_abs_ns = jiffies_to_st(j) + NS_PER_TICK/2;
+       singleshot.timeout_abs_ns = jiffies_to_st(j);
+       if (!singleshot.timeout_abs_ns)
+               return;
+       singleshot.timeout_abs_ns += NS_PER_TICK / 2;
        singleshot.flags = 0;
        rc = HYPERVISOR_vcpu_op(VCPUOP_set_singleshot_timer, cpu, &singleshot);
 #if CONFIG_XEN_COMPAT <= 0x030004
@@ -953,7 +956,17 @@ static void stop_hz_timer(void)
 
 static void start_hz_timer(void)
 {
-       cpu_clear(smp_processor_id(), nohz_cpu_mask);
+       unsigned int cpu = smp_processor_id();
+       int rc = HYPERVISOR_vcpu_op(VCPUOP_stop_singleshot_timer, cpu, NULL);
+
+#if CONFIG_XEN_COMPAT <= 0x030004
+       if (rc) {
+               BUG_ON(rc != -ENOSYS);
+               rc = HYPERVISOR_set_timer_op(0);
+       }
+#endif
+       BUG_ON(rc);
+       cpu_clear(cpu, nohz_cpu_mask);
 }
 
 void raw_safe_halt(void)




_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel