[Xen-changelog] [xen staging] xen: don't free percpu areas during suspend

[patchbot@xxxxxxx]

commit aca2a985a55ad9a0fcc1a9f23c8c4755598928ec
Author:     Juergen Gross <jgross@xxxxxxxx>
AuthorDate: Tue Apr 2 07:34:55 2019 +0200
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Thu Apr 4 11:10:12 2019 +0100

    xen: don't free percpu areas during suspend
    
    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 <jgross@xxxxxxxx>
    Reviewed-by: Dario Faggioli <dfaggioli@xxxxxxxx>
    Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 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(
         break;
     case CPU_UP_CANCELED:
     case CPU_DEAD:
-        if ( !park_offline_cpus )
+    case CPU_RESUME_FAILED:
+        if ( !park_offline_cpus && system_state != SYS_STATE_suspend )
             free_percpu_area(cpu);
         break;
     case CPU_REMOVE:
--
generated by git-patchbot for /home/xen/git/xen.git#staging

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