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From: Juergen Gross <>
Cc: "Juergen Gross" <>,
	"Andrew Cooper" <>,
	"Wei Liu" <>,
	"Jan Beulich" <>,
	"Roger Pau Monné" <>
Subject: [PATCH v4 4/6] xen: don't free percpu areas during suspend
Date: Tue,  2 Apr 2019 18:19:08 +0200	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

Instead of freeing percpu areas during suspend and allocating them
again when resuming keep them. Only free an area in case a cpu didn't
come up again when resuming.

It should be noted that there is a potential change in behaviour as
the percpu areas are no longer zeroed out during suspend/resume. While
I have checked the called cpu notifier hooks to cope with that there
might be some well hidden dependency on the previous behaviour. OTOH
a component not registering itself for cpu down/up and expecting to
see a zeroed percpu variable after suspend/resume is kind of broken
already. And the opposite case, where a component is not registered
to be called for cpu down/up and is not expecting a percpu variable
suddenly to be zero due to suspend/resume is much more probable,
especially as the suspend/resume functionality seems not to be tested
that often.

Signed-off-by: Juergen Gross <>
Reviewed-by: Dario Faggioli <>
Acked-by: Jan Beulich <>
 xen/arch/x86/percpu.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/xen/arch/x86/percpu.c b/xen/arch/x86/percpu.c
index 8be4ebddf4..5ea14b6ec3 100644
--- a/xen/arch/x86/percpu.c
+++ b/xen/arch/x86/percpu.c
@@ -76,7 +76,8 @@ static int cpu_percpu_callback(
     case CPU_UP_CANCELED:
     case CPU_DEAD:
-        if ( !park_offline_cpus )
+        if ( !park_offline_cpus && system_state != SYS_STATE_suspend )
     case CPU_REMOVE:

Xen-devel mailing list

  parent reply	other threads:[~2019-04-02 16:19 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-02 16:19 [PATCH v4 0/6] xen: simplify suspend/resume handling Juergen Gross
2019-04-02 16:19 ` [PATCH v4 1/6] xen/sched: call cpu_disable_scheduler() via cpu notifier Juergen Gross
2019-04-04 13:06   ` Dario Faggioli
2019-04-02 16:19 ` [PATCH v4 2/6] xen: add helper for calling notifier_call_chain() to common/cpu.c Juergen Gross
2019-04-02 16:19 ` [PATCH v4 3/6] xen: add new cpu notifier action CPU_RESUME_FAILED Juergen Gross
2019-04-02 16:19 ` Juergen Gross [this message]
2019-04-02 16:19 ` [PATCH v4 5/6] xen/cpupool: simplify suspend/resume handling Juergen Gross
2019-04-02 16:19 ` [PATCH v4 6/6] xen/sched: don't disable scheduler on cpus during suspend Juergen Gross

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