[Xen-changelog] [xen stable-4.9] xen: Introduce vcpu_sleep_nosync_locked()

[patchbot@xxxxxxx]

commit 002ea4d14a2a62e405941a65099f7f2ff5eceebe
Author:     George Dunlap <george.dunlap@xxxxxxxxxx>
AuthorDate: Fri May 18 11:59:09 2018 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri May 18 11:59:09 2018 +0200

    xen: Introduce vcpu_sleep_nosync_locked()
    
    There are a lot of places which release a lock before calling
    vcpu_sleep_nosync(), which then just grabs the lock again.  This is
    not only a waste of time, but leads to more code duplication (since
    you have to copy-and-paste recipes rather than calling a unified
    function), which in turn leads to an increased chance of bugs.
    
    Introduce vcpu_sleep_nosync_locked(), which can be called if you
    already hold the schedule lock.
    
    Signed-off-by: George Dunlap <george.dunlap@xxxxxxxxxx>
    Reviewed-by: Dario Faggioli <dfaggioli@xxxxxxxx>
    master commit: da0a5e00de8aa93f2a7482d138dbee9dec2aa5c2
    master date: 2018-05-03 11:56:36 +0100
---
 xen/common/schedule.c | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/xen/common/schedule.c b/xen/common/schedule.c
index 1058e19b6e..7769eaac13 100644
--- a/xen/common/schedule.c
+++ b/xen/common/schedule.c
@@ -436,14 +436,9 @@ void sched_destroy_domain(struct domain *d)
     cpupool_rm_domain(d);
 }
 
-void vcpu_sleep_nosync(struct vcpu *v)
+void vcpu_sleep_nosync_locked(struct vcpu *v)
 {
-    unsigned long flags;
-    spinlock_t *lock;
-
-    TRACE_2D(TRC_SCHED_SLEEP, v->domain->domain_id, v->vcpu_id);
-
-    lock = vcpu_schedule_lock_irqsave(v, &flags);
+    ASSERT(spin_is_locked(per_cpu(schedule_data,v->processor).schedule_lock));
 
     if ( likely(!vcpu_runnable(v)) )
     {
@@ -452,6 +447,18 @@ void vcpu_sleep_nosync(struct vcpu *v)
 
         SCHED_OP(vcpu_scheduler(v), sleep, v);
     }
+}
+
+void vcpu_sleep_nosync(struct vcpu *v)
+{
+    unsigned long flags;
+    spinlock_t *lock;
+
+    TRACE_2D(TRC_SCHED_SLEEP, v->domain->domain_id, v->vcpu_id);
+
+    lock = vcpu_schedule_lock_irqsave(v, &flags);
+
+    vcpu_sleep_nosync_locked(v);
 
     vcpu_schedule_unlock_irqrestore(lock, flags, v);
 }
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.9

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