* [PATCH for v4.9] livepatch: Wrong usage of spinlock on debug console.
@ 2017-06-09 14:16 Konrad Rzeszutek Wilk
2017-06-09 14:53 ` Jan Beulich
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Konrad Rzeszutek Wilk @ 2017-06-09 14:16 UTC (permalink / raw)
To: xen-devel
Cc: Konrad Rzeszutek Wilk, Andrew Cooper, Ross Lagerwall,
Julien Grall, Jan Beulich, Boris Ostrovsky
If we have a large amount of livepatches and want to print them
on the console using 'xl debug-keys x' we eventually hit
the preemption check:
if ( i && !(i % 64) )
{
spin_unlock(&payload_lock);
process_pending_softirqs();
if ( spin_trylock(&payload_lock) )
return
<facepalm> The effect is that we have just effectively
taken the lock and returned without unlocking!
CC: Ross Lagerwall <ross.lagerwall@citrix.com>
CC: Boris Ostrovsky <boris.ostrovsky@oracle.com>
CC: Jan Beulich <jbeulich@suse.com>
CC: Andrew Cooper <andrew.cooper3@citrix.com>
CC: Julien Grall <julien.grall@arm.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
xen/common/livepatch.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/xen/common/livepatch.c b/xen/common/livepatch.c
index f14bcbc..df67a1a 100644
--- a/xen/common/livepatch.c
+++ b/xen/common/livepatch.c
@@ -1642,7 +1642,7 @@ static void livepatch_printall(unsigned char key)
{
spin_unlock(&payload_lock);
process_pending_softirqs();
- if ( spin_trylock(&payload_lock) )
+ if ( !spin_trylock(&payload_lock) )
{
printk("Couldn't reacquire lock. Try again.\n");
return;
--
2.9.3
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^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH for v4.9] livepatch: Wrong usage of spinlock on debug console.
2017-06-09 14:16 [PATCH for v4.9] livepatch: Wrong usage of spinlock on debug console Konrad Rzeszutek Wilk
@ 2017-06-09 14:53 ` Jan Beulich
2017-06-09 15:05 ` Ross Lagerwall
2017-06-09 17:12 ` Boris Ostrovsky
2 siblings, 0 replies; 6+ messages in thread
From: Jan Beulich @ 2017-06-09 14:53 UTC (permalink / raw)
To: Konrad Rzeszutek Wilk
Cc: Boris Ostrovsky, Andrew Cooper, Julien Grall, xen-devel,
Ross Lagerwall
>>> On 09.06.17 at 16:16, <konrad.wilk@oracle.com> wrote:
> If we have a large amount of livepatches and want to print them
> on the console using 'xl debug-keys x' we eventually hit
> the preemption check:
>
> if ( i && !(i % 64) )
> {
> spin_unlock(&payload_lock);
> process_pending_softirqs();
> if ( spin_trylock(&payload_lock) )
> return
>
> <facepalm> The effect is that we have just effectively
> taken the lock and returned without unlocking!
>
> CC: Ross Lagerwall <ross.lagerwall@citrix.com>
> CC: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> CC: Jan Beulich <jbeulich@suse.com>
> CC: Andrew Cooper <andrew.cooper3@citrix.com>
> CC: Julien Grall <julien.grall@arm.com>
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
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^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH for v4.9] livepatch: Wrong usage of spinlock on debug console.
2017-06-09 14:16 [PATCH for v4.9] livepatch: Wrong usage of spinlock on debug console Konrad Rzeszutek Wilk
2017-06-09 14:53 ` Jan Beulich
@ 2017-06-09 15:05 ` Ross Lagerwall
2017-06-09 17:12 ` Boris Ostrovsky
2 siblings, 0 replies; 6+ messages in thread
From: Ross Lagerwall @ 2017-06-09 15:05 UTC (permalink / raw)
To: Konrad Rzeszutek Wilk, xen-devel
Cc: Andrew Cooper, Boris Ostrovsky, Julien Grall, Jan Beulich
On 06/09/2017 03:16 PM, Konrad Rzeszutek Wilk wrote:
> If we have a large amount of livepatches and want to print them
> on the console using 'xl debug-keys x' we eventually hit
> the preemption check:
>
> if ( i && !(i % 64) )
> {
> spin_unlock(&payload_lock);
> process_pending_softirqs();
> if ( spin_trylock(&payload_lock) )
> return
>
> <facepalm> The effect is that we have just effectively
> taken the lock and returned without unlocking!
>
> CC: Ross Lagerwall <ross.lagerwall@citrix.com>
> CC: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> CC: Jan Beulich <jbeulich@suse.com>
> CC: Andrew Cooper <andrew.cooper3@citrix.com>
> CC: Julien Grall <julien.grall@arm.com>
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> ---
Reviewed-by: Ross Lagerwall <ross.lagerwall@citrix.com>
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^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH for v4.9] livepatch: Wrong usage of spinlock on debug console.
2017-06-09 14:16 [PATCH for v4.9] livepatch: Wrong usage of spinlock on debug console Konrad Rzeszutek Wilk
2017-06-09 14:53 ` Jan Beulich
2017-06-09 15:05 ` Ross Lagerwall
@ 2017-06-09 17:12 ` Boris Ostrovsky
2017-06-11 12:15 ` Is: Release-ack for 4.9, Is:Re: " Konrad Rzeszutek Wilk
2 siblings, 1 reply; 6+ messages in thread
From: Boris Ostrovsky @ 2017-06-09 17:12 UTC (permalink / raw)
To: Konrad Rzeszutek Wilk, xen-devel
Cc: Ross Lagerwall, Julien Grall, Jan Beulich, Andrew Cooper
On 06/09/2017 10:16 AM, Konrad Rzeszutek Wilk wrote:
> If we have a large amount of livepatches and want to print them
> on the console using 'xl debug-keys x' we eventually hit
> the preemption check:
>
> if ( i && !(i % 64) )
> {
> spin_unlock(&payload_lock);
> process_pending_softirqs();
> if ( spin_trylock(&payload_lock) )
> return
>
> <facepalm> The effect is that we have just effectively
> taken the lock and returned without unlocking!
>
> CC: Ross Lagerwall <ross.lagerwall@citrix.com>
> CC: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> CC: Jan Beulich <jbeulich@suse.com>
> CC: Andrew Cooper <andrew.cooper3@citrix.com>
> CC: Julien Grall <julien.grall@arm.com>
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-and-tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
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^ permalink raw reply [flat|nested] 6+ messages in thread* Is: Release-ack for 4.9, Is:Re: [PATCH for v4.9] livepatch: Wrong usage of spinlock on debug console.
2017-06-09 17:12 ` Boris Ostrovsky
@ 2017-06-11 12:15 ` Konrad Rzeszutek Wilk
2017-06-12 11:08 ` Julien Grall
0 siblings, 1 reply; 6+ messages in thread
From: Konrad Rzeszutek Wilk @ 2017-06-11 12:15 UTC (permalink / raw)
To: Boris Ostrovsky
Cc: xen-devel, Julien Grall, Andrew Cooper, Jan Beulich,
Ross Lagerwall
On Fri, Jun 09, 2017 at 01:12:10PM -0400, Boris Ostrovsky wrote:
> On 06/09/2017 10:16 AM, Konrad Rzeszutek Wilk wrote:
> > If we have a large amount of livepatches and want to print them
> > on the console using 'xl debug-keys x' we eventually hit
> > the preemption check:
> >
> > if ( i && !(i % 64) )
> > {
> > spin_unlock(&payload_lock);
> > process_pending_softirqs();
> > if ( spin_trylock(&payload_lock) )
> > return
> >
> > <facepalm> The effect is that we have just effectively
> > taken the lock and returned without unlocking!
> >
> > CC: Ross Lagerwall <ross.lagerwall@citrix.com>
> > CC: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> > CC: Jan Beulich <jbeulich@suse.com>
> > CC: Andrew Cooper <andrew.cooper3@citrix.com>
> > CC: Julien Grall <julien.grall@arm.com>
Julien, could you Release-Ack it for 4.9 please?
> > Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
>
>
> Reviewed-and-tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
>
>
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^ permalink raw reply [flat|nested] 6+ messages in thread* Re: Is: Release-ack for 4.9, Is:Re: [PATCH for v4.9] livepatch: Wrong usage of spinlock on debug console.
2017-06-11 12:15 ` Is: Release-ack for 4.9, Is:Re: " Konrad Rzeszutek Wilk
@ 2017-06-12 11:08 ` Julien Grall
0 siblings, 0 replies; 6+ messages in thread
From: Julien Grall @ 2017-06-12 11:08 UTC (permalink / raw)
To: Konrad Rzeszutek Wilk, Boris Ostrovsky
Cc: xen-devel, Andrew Cooper, Jan Beulich, Ross Lagerwall
Hi Konrad,
On 11/06/17 13:15, Konrad Rzeszutek Wilk wrote:
> On Fri, Jun 09, 2017 at 01:12:10PM -0400, Boris Ostrovsky wrote:
>> On 06/09/2017 10:16 AM, Konrad Rzeszutek Wilk wrote:
>>> If we have a large amount of livepatches and want to print them
>>> on the console using 'xl debug-keys x' we eventually hit
>>> the preemption check:
>>>
>>> if ( i && !(i % 64) )
>>> {
>>> spin_unlock(&payload_lock);
>>> process_pending_softirqs();
>>> if ( spin_trylock(&payload_lock) )
>>> return
>>>
>>> <facepalm> The effect is that we have just effectively
>>> taken the lock and returned without unlocking!
>>>
>>> CC: Ross Lagerwall <ross.lagerwall@citrix.com>
>>> CC: Boris Ostrovsky <boris.ostrovsky@oracle.com>
>>> CC: Jan Beulich <jbeulich@suse.com>
>>> CC: Andrew Cooper <andrew.cooper3@citrix.com>
>>> CC: Julien Grall <julien.grall@arm.com>
>
> Julien, could you Release-Ack it for 4.9 please?
Sure:
Release-acked-by: Julien Grall <julien.grall@arm.com>
Cheers,
--
Julien Grall
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^ permalink raw reply [flat|nested] 6+ messages in thread
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2017-06-09 14:16 [PATCH for v4.9] livepatch: Wrong usage of spinlock on debug console Konrad Rzeszutek Wilk
2017-06-09 14:53 ` Jan Beulich
2017-06-09 15:05 ` Ross Lagerwall
2017-06-09 17:12 ` Boris Ostrovsky
2017-06-11 12:15 ` Is: Release-ack for 4.9, Is:Re: " Konrad Rzeszutek Wilk
2017-06-12 11:08 ` Julien Grall
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