[Xen-devel] [PATCH] xen: RTDS: fix another instance of the 'read NOW()' race

[Dario Faggioli <dario.faggioli@xxxxxxxxxx>]

which was overlooked in 779511f4bf5ae ("sched: avoid
races on time values read from NOW()").

Reported-by: Jan Beulich <jbeulich@xxxxxxxx>
Signed-off-by: Dario Faggioli <dario.faggioli@xxxxxxxxxx>
---
Cc: Meng Xu <mengxu@xxxxxxxxxxxxx>
Cc: George Dunlap <george.dunlap@xxxxxxxxxx>
Cc: Jan Beulich <JBeulich@xxxxxxxx>
Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
---
 xen/common/sched_rt.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/xen/common/sched_rt.c b/xen/common/sched_rt.c
index 0946101..5b077d7 100644
--- a/xen/common/sched_rt.c
+++ b/xen/common/sched_rt.c
@@ -840,12 +840,14 @@ static void
 rt_vcpu_insert(const struct scheduler *ops, struct vcpu *vc)
 {
     struct rt_vcpu *svc = rt_vcpu(vc);
-    s_time_t now = NOW();
+    s_time_t now;
     spinlock_t *lock;
 
     BUG_ON( is_idle_vcpu(vc) );
 
     lock = vcpu_schedule_lock_irq(vc);
+
+    now = NOW();
     if ( now >= svc->cur_deadline )
         rt_update_deadline(now, svc);
 


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