[xen stable-4.13] sched: fix error path in cpupool_unassign_cpu_start()

[patchbot@xxxxxxx]

commit e1e24c5e5563c34f5e063924e4b13aa3d169ed03
Author:     Juergen Gross <jgross@xxxxxxxx>
AuthorDate: Thu Apr 9 09:05:26 2020 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Apr 9 09:05:26 2020 +0200

    sched: fix error path in cpupool_unassign_cpu_start()
    
    In case moving away all domains from the cpu to be removed is failing
    in cpupool_unassign_cpu_start() the error path is missing to release
    sched_res_rculock.
    
    The normal exit path is releasing domlist_read_lock instead (this is
    currently no problem as the reference to the specific rcu lock is not
    used by rcu_read_unlock()).
    
    While at it indent the present error label by one space.
    
    Reported-by: Igor Druzhinin <igor.druzhinin@xxxxxxxxxx>
    Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Dario Faggioli <dfaggioli@xxxxxxxx>
    master commit: 98ed1f43cc2c89efd38deed1035dba5b1ced5d45
    master date: 2020-03-03 16:02:32 +0100
---
 xen/common/cpupool.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/xen/common/cpupool.c b/xen/common/cpupool.c
index 4d3adbdd8d..5a90bdc9ff 100644
--- a/xen/common/cpupool.c
+++ b/xen/common/cpupool.c
@@ -465,7 +465,7 @@ static int cpupool_unassign_cpu_start(struct cpupool *c, 
unsigned int cpu)
         }
         rcu_read_unlock(&domlist_read_lock);
         if ( ret )
-            goto out;
+            goto out_rcu;
     }
     cpupool_moving_cpu = cpu;
     atomic_inc(&c->refcnt);
@@ -473,8 +473,9 @@ static int cpupool_unassign_cpu_start(struct cpupool *c, 
unsigned int cpu)
     cpumask_andnot(c->cpu_valid, c->cpu_valid, cpus);
     cpumask_and(c->res_valid, c->cpu_valid, &sched_res_mask);
 
-    rcu_read_unlock(&domlist_read_lock);
-out:
+ out_rcu:
+    rcu_read_unlock(&sched_res_rculock);
+ out:
     spin_unlock(&cpupool_lock);
 
     return ret;
--
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