Keir,
Thanks for comments and update!
However, I think we still need update it a little :)
=============================
Fix cpu offline bug
Remove BUG_ON since it's of some risk, considering the small time window:
cpu0 read (cpu_state) --> offlining cpu write (cpu_state) --> cpu0 read
(cpu_state)
Signed-off-by: Liu, Jinsong <jinsong.liu@xxxxxxxxx>
diff -r 1ecb840bea17 xen/arch/x86/smpboot.c
--- a/xen/arch/x86/smpboot.c Sat Mar 05 23:30:29 2022 +0800
+++ b/xen/arch/x86/smpboot.c Sun Mar 06 01:21:34 2022 +0800
@@ -864,7 +864,6 @@ void __cpu_die(unsigned int cpu)
while ( cpu_state != CPU_STATE_DEAD )
{
- BUG_ON(cpu_state != CPU_STATE_DYING);
mdelay(100);
cpu_relax();
process_pending_softirqs();
=============================
Thanks,
Jinsong
Keir Fraser wrote:
> On 04/03/2011 10:22, "Liu, Jinsong" <jinsong.liu@xxxxxxxxx> wrote:
>
>> Fix cpu offline bug
>>
>> At current xen, when cpu offline, cpu0 will wait the 1st cpu offline;
>> However, if offline 2nd, 3rd, ... cpu, cpu0 will not wait it.
>> This patch is used to fix the bug.
>
> Alternative fix applied tio unstable and 4.1-testing. The fix below
> doesn't account for the fact that cpu_state can also ==
> CPU_STATE_DEAD after an (unsuccessful) CPU online operation.
>
> -- Keir
>
>> Signed-off-by: Liu, Jinsong <jinsong.liu@xxxxxxxxx>
>>
>> diff -r d1631540bcc4 xen/arch/x86/smpboot.c
>> --- a/xen/arch/x86/smpboot.c Tue Jan 18 17:23:24 2011 +0000
>> +++ b/xen/arch/x86/smpboot.c Sat Feb 12 03:48:09 2011 +0800
>> @@ -78,7 +78,8 @@ static enum cpu_state {
>> CPU_STATE_INIT, /* master -> slave: Early bringup phase 1 */
>> CPU_STATE_CALLOUT, /* master -> slave: Early bringup phase 2 */
>> CPU_STATE_CALLIN, /* slave -> master: Completed phase 2 */
>> - CPU_STATE_ONLINE /* master -> slave: Go fully online now. */
>> + CPU_STATE_ONLINE, /* master -> slave: Go fully online now. */
>> + CPU_STATE_STAY /* after slave dead, global cpu_state stay
>> here */ } cpu_state; #define set_cpu_state(state) do { mb();
>> cpu_state = (state); } while (0)
>>
>> @@ -867,6 +868,8 @@ void __cpu_die(unsigned int cpu)
>> if ( (++i % 10) == 0 )
>> printk(KERN_ERR "CPU %u still not dead...\n", cpu);
>> } +
>> + set_cpu_state(CPU_STATE_STAY);
>> }
>>
>> int cpu_add(uint32_t apic_id, uint32_t acpi_id, uint32_t pxm)
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