diff mbox

ipmi: do not take/drop iothread lock

Message ID 1453824953-27230-1-git-send-email-pbonzini@redhat.com (mailing list archive)
State New, archived
Headers show

Commit Message

Paolo Bonzini Jan. 26, 2016, 4:15 p.m. UTC
This is not necessary and actually causes a hang; it was probably copied
and pasted from KVM code, that is one of the very few places that run
outside iothread lock.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 hw/ipmi/ipmi.c | 2 --
 1 file changed, 2 deletions(-)

Comments

Michael S. Tsirkin Jan. 26, 2016, 4:21 p.m. UTC | #1
On Tue, Jan 26, 2016 at 05:15:53PM +0100, Paolo Bonzini wrote:
> This is not necessary and actually causes a hang; it was probably copied
> and pasted from KVM code, that is one of the very few places that run
> outside iothread lock.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Makes sense. I wonder how hard would it be to have a test to catch this.

> ---
>  hw/ipmi/ipmi.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/hw/ipmi/ipmi.c b/hw/ipmi/ipmi.c
> index 52aba1e..fcba0ca 100644
> --- a/hw/ipmi/ipmi.c
> +++ b/hw/ipmi/ipmi.c
> @@ -50,9 +50,7 @@ static int ipmi_do_hw_op(IPMIInterface *s, enum ipmi_op op, int checkonly)
>          if (checkonly) {
>              return 0;
>          }
> -        qemu_mutex_lock_iothread();
>          qmp_inject_nmi(NULL);
> -        qemu_mutex_unlock_iothread();
>          return 0;
>  
>      case IPMI_POWERCYCLE_CHASSIS:
> -- 
> 2.5.0
Corey Minyard Jan. 26, 2016, 5:57 p.m. UTC | #2
On 01/26/2016 10:21 AM, Michael S. Tsirkin wrote:
> On Tue, Jan 26, 2016 at 05:15:53PM +0100, Paolo Bonzini wrote:
>> This is not necessary and actually causes a hang; it was probably copied
>> and pasted from KVM code, that is one of the very few places that run
>> outside iothread lock.
>>
>> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> Makes sense. I wonder how hard would it be to have a test to catch this.

The IPMI side would be easy for me, but I don't know how to handle 
catching the NMI.

-corey

>> ---
>>   hw/ipmi/ipmi.c | 2 --
>>   1 file changed, 2 deletions(-)
>>
>> diff --git a/hw/ipmi/ipmi.c b/hw/ipmi/ipmi.c
>> index 52aba1e..fcba0ca 100644
>> --- a/hw/ipmi/ipmi.c
>> +++ b/hw/ipmi/ipmi.c
>> @@ -50,9 +50,7 @@ static int ipmi_do_hw_op(IPMIInterface *s, enum ipmi_op op, int checkonly)
>>           if (checkonly) {
>>               return 0;
>>           }
>> -        qemu_mutex_lock_iothread();
>>           qmp_inject_nmi(NULL);
>> -        qemu_mutex_unlock_iothread();
>>           return 0;
>>   
>>       case IPMI_POWERCYCLE_CHASSIS:
>> -- 
>> 2.5.0
Paolo Bonzini Jan. 26, 2016, 6 p.m. UTC | #3
On 26/01/2016 18:57, Corey Minyard wrote:
> On 01/26/2016 10:21 AM, Michael S. Tsirkin wrote:
>> On Tue, Jan 26, 2016 at 05:15:53PM +0100, Paolo Bonzini wrote:
>>> This is not necessary and actually causes a hang; it was probably copied
>>> and pasted from KVM code, that is one of the very few places that run
>>> outside iothread lock.
>>>
>>> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
>> Makes sense. I wonder how hard would it be to have a test to catch this.
> 
> The IPMI side would be easy for me, but I don't know how to handle
> catching the NMI.

I'm afraid there's no way to trap an NMI from qtest.

Paolo
diff mbox

Patch

diff --git a/hw/ipmi/ipmi.c b/hw/ipmi/ipmi.c
index 52aba1e..fcba0ca 100644
--- a/hw/ipmi/ipmi.c
+++ b/hw/ipmi/ipmi.c
@@ -50,9 +50,7 @@  static int ipmi_do_hw_op(IPMIInterface *s, enum ipmi_op op, int checkonly)
         if (checkonly) {
             return 0;
         }
-        qemu_mutex_lock_iothread();
         qmp_inject_nmi(NULL);
-        qemu_mutex_unlock_iothread();
         return 0;
 
     case IPMI_POWERCYCLE_CHASSIS: