linux: panic/shutdown handling adjustments

PATCH New Jan Beulich 1 participant 1 message Oct 25, 2007 Xen hypervisor interface

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Jan Beulich

author

2007-10-25 09:42 UTC #0 lore raw

PATCH 1/1 linux: panic/shutdown handling adjustments

Prevent interrupts (and hence possibly scheduler operations) from occuring on (against) a CPU after removing it from cpu_online_map during panic/shutdown.
(Background: I found it quite annoying to see scheduler related badness or BUG messages after a panic, eventually even leading to important information scrolling off the screen.)

As usual, written and tested against 2.6.23 and made apply against 2.6.18 without further testing.

Signed-off-by Jan Beulich <[email protected]>

arch/i386/kernel/smp-xen.c +2 -6

Index: head-2007-10-15/arch/i386/kernel/smp-xen.c
===================================================================
@@ -595,9 +595,7 @@ static void stop_this_cpu (void * dummy)
 	 */
 	cpu_clear(smp_processor_id(), cpu_online_map);
 	local_irq_disable();
-#if 0
-	disable_local_APIC();
-#endif
+	mask_evtchn_local();
 	if (cpu_data[smp_processor_id()].hlt_works_ok)
 		for(;;) halt();
 	for (;;);

@@ -617,9 +615,7 @@ void xen_smp_send_stop(void)
 	smp_call_function(stop_this_cpu, NULL, 1, 0);
 
 	local_irq_disable();
-#if 0
-	disable_local_APIC();
-#endif
+	mask_evtchn_local();
 	local_irq_enable();
 }

arch/x86_64/kernel/smp-xen.c +2 -6

Index: head-2007-10-15/arch/x86_64/kernel/smp-xen.c
===================================================================
@@ -488,9 +488,7 @@ void smp_stop_cpu(void)
 	 */
 	cpu_clear(smp_processor_id(), cpu_online_map);
 	local_irq_save(flags);
-#ifndef CONFIG_XEN
-	disable_local_APIC();
-#endif
+	mask_evtchn_local();
 	local_irq_restore(flags); 
 }

@@ -511,9 +509,7 @@ void smp_send_stop(void)
 		spin_unlock(&call_lock);
 
 	local_irq_disable();
-#ifndef CONFIG_XEN
-	disable_local_APIC();
-#endif
+	mask_evtchn_local();
 	local_irq_enable();
 }

drivers/xen/core/evtchn.c +10 -0

Index: head-2007-10-15/drivers/xen/core/evtchn.c
===================================================================
@@ -157,6 +157,16 @@ static inline unsigned int cpu_from_evtc
 	return cpu_evtchn[evtchn];
 }
 
+void mask_evtchn_local(void)
+{
+	unsigned i, cpu = smp_processor_id();
+	shared_info_t *s = HYPERVISOR_shared_info;
+
+	for (i = 0; i < NR_EVENT_CHANNELS; ++i)
+		if (cpu_evtchn[i] == cpu)
+			synch_set_bit(i, &s->evtchn_mask[0]);
+}
+
 #else
 
 static inline unsigned long active_evtchns(unsigned int cpu, shared_info_t *sh,

include/xen/evtchn.h +1 -0

Index: head-2007-10-15/include/xen/evtchn.h
===================================================================
@@ -102,6 +102,7 @@ asmlinkage void evtchn_do_upcall(struct 
 void evtchn_device_upcall(int port);
 
 void mask_evtchn(int port);
+void mask_evtchn_local(void);
 void unmask_evtchn(int port);
 
 #ifdef CONFIG_SMP