[Xen-changelog] [xen master] xen: sched: avoid spuriously re-enabling IRQs in csched2_switch_sched()

[patchbot@xxxxxxx]

commit fb0c3a8a30906005afc8c976b5c469d86496871e
Author:     Dario Faggioli <dario.faggioli@xxxxxxxxxx>
AuthorDate: Tue Apr 26 18:56:56 2016 +0200
Commit:     George Dunlap <george.dunlap@xxxxxxxxxx>
CommitDate: Mon May 9 15:41:25 2016 +0100

    xen: sched: avoid spuriously re-enabling IRQs in csched2_switch_sched()
    
    interrupts are already disabled when calling the hook
    (from schedule_cpu_switch()), so we must use spin_lock()
    and spin_unlock().
    
    Add an ASSERT(), so we will notice if this code and its
    caller get out of sync with respect to disabling interrupts
    (and add one at the same exact occurrence of this pattern
    in Credit1 too)
    
    Signed-off-by: Dario Faggioli <dario.faggioli@xxxxxxxxxx>
    Reviewed-by: George Dunlap <george.dunlap@xxxxxxxxxx>
    Release-acked-by: Wei Liu <wei.liu2@xxxxxxxxxx>
---
 xen/common/sched_credit.c  | 1 +
 xen/common/sched_credit2.c | 5 +++--
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/xen/common/sched_credit.c b/xen/common/sched_credit.c
index db4d42a..a38a63d 100644
--- a/xen/common/sched_credit.c
+++ b/xen/common/sched_credit.c
@@ -615,6 +615,7 @@ csched_switch_sched(struct scheduler *new_ops, unsigned int 
cpu,
      * schedule_cpu_switch()). It actually may or may not be the 'right'
      * one for this cpu, but that is ok for preventing races.
      */
+    ASSERT(!local_irq_is_enabled());
     spin_lock(&prv->lock);
     init_pdata(prv, pdata, cpu);
     spin_unlock(&prv->lock);
diff --git a/xen/common/sched_credit2.c b/xen/common/sched_credit2.c
index f3b62ac..f95e509 100644
--- a/xen/common/sched_credit2.c
+++ b/xen/common/sched_credit2.c
@@ -2238,7 +2238,8 @@ csched2_switch_sched(struct scheduler *new_ops, unsigned 
int cpu,
      * And owning exactly that one (the lock of the old scheduler of this
      * cpu) is what is necessary to prevent races.
      */
-    spin_lock_irq(&prv->lock);
+    ASSERT(!local_irq_is_enabled());
+    spin_lock(&prv->lock);
 
     idle_vcpu[cpu]->sched_priv = vdata;
 
@@ -2263,7 +2264,7 @@ csched2_switch_sched(struct scheduler *new_ops, unsigned 
int cpu,
     smp_mb();
     per_cpu(schedule_data, cpu).schedule_lock = &prv->rqd[rqi].lock;
 
-    spin_unlock_irq(&prv->lock);
+    spin_unlock(&prv->lock);
 }
 
 static void
--
generated by git-patchbot for /home/xen/git/xen.git#master

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