[Xen-changelog] [xen-unstable] cpupool: Check for memory allocation failure on switching schedulers

[Xen patchbot-unstable <patchbot@xxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir@xxxxxxx>
# Date 1297008447 0
# Node ID 23f60ba52fffccd3916b643e0654209117765908
# Parent  544b103b4d972bd17afdb260acfcde75a78658d8
cpupool: Check for memory allocation failure on switching schedulers

When switching schedulers on a physical cpu due to a cpupool operation
check for a potential memory allocation failure and stop the operation
gracefully.

Signed-off-by: Juergen Gross <juergen.gross@xxxxxxxxxxxxxx>
---
 xen/common/cpupool.c    |   21 +++++++++++++++++++--
 xen/common/schedule.c   |   13 +++++++++++--
 xen/include/xen/sched.h |    2 +-
 3 files changed, 31 insertions(+), 5 deletions(-)

diff -r 544b103b4d97 -r 23f60ba52fff xen/common/cpupool.c
--- a/xen/common/cpupool.c      Fri Feb 04 18:47:39 2011 +0000
+++ b/xen/common/cpupool.c      Sun Feb 06 16:07:27 2011 +0000
@@ -202,10 +202,20 @@ static int cpupool_destroy(struct cpupoo
  */
 static int cpupool_assign_cpu_locked(struct cpupool *c, unsigned int cpu)
 {
+    int ret;
+    struct cpupool *old;
+
     if ( (cpupool_moving_cpu == cpu) && (c != cpupool_cpu_moving) )
         return -EBUSY;
+    old = per_cpu(cpupool, cpu);
     per_cpu(cpupool, cpu) = c;
-    schedule_cpu_switch(cpu, c);
+    ret = schedule_cpu_switch(cpu, c);
+    if ( ret )
+    {
+        per_cpu(cpupool, cpu) = old;
+        return ret;
+    }
+
     cpu_clear(cpu, cpupool_free_cpus);
     if (cpupool_moving_cpu == cpu)
     {
@@ -230,12 +240,19 @@ static long cpupool_unassign_cpu_helper(
     cpu_set(cpu, cpupool_free_cpus);
     if ( !ret )
     {
-        schedule_cpu_switch(cpu, NULL);
+        ret = schedule_cpu_switch(cpu, NULL);
+        if ( ret )
+        {
+            cpu_clear(cpu, cpupool_free_cpus);
+            goto out;
+        }
         per_cpu(cpupool, cpu) = NULL;
         cpupool_moving_cpu = -1;
         cpupool_put(cpupool_cpu_moving);
         cpupool_cpu_moving = NULL;
     }
+
+out:
     spin_unlock(&cpupool_lock);
     return ret;
 }
diff -r 544b103b4d97 -r 23f60ba52fff xen/common/schedule.c
--- a/xen/common/schedule.c     Fri Feb 04 18:47:39 2011 +0000
+++ b/xen/common/schedule.c     Sun Feb 06 16:07:27 2011 +0000
@@ -1288,7 +1288,7 @@ void __init scheduler_init(void)
         BUG();
 }
 
-void schedule_cpu_switch(unsigned int cpu, struct cpupool *c)
+int schedule_cpu_switch(unsigned int cpu, struct cpupool *c)
 {
     unsigned long flags;
     struct vcpu *idle;
@@ -1297,11 +1297,18 @@ void schedule_cpu_switch(unsigned int cp
     struct scheduler *new_ops = (c == NULL) ? &ops : c->sched;
 
     if ( old_ops == new_ops )
-        return;
+        return 0;
 
     idle = idle_vcpu[cpu];
     ppriv = SCHED_OP(new_ops, alloc_pdata, cpu);
+    if ( ppriv == NULL )
+        return -ENOMEM;
     vpriv = SCHED_OP(new_ops, alloc_vdata, idle, idle->domain->sched_priv);
+    if ( vpriv == NULL )
+    {
+        SCHED_OP(new_ops, free_pdata, ppriv, cpu);
+        return -ENOMEM;
+    }
 
     pcpu_schedule_lock_irqsave(cpu, flags);
 
@@ -1318,6 +1325,8 @@ void schedule_cpu_switch(unsigned int cp
 
     SCHED_OP(old_ops, free_vdata, vpriv_old);
     SCHED_OP(old_ops, free_pdata, ppriv_old, cpu);
+
+    return 0;
 }
 
 struct scheduler *scheduler_get_default(void)
diff -r 544b103b4d97 -r 23f60ba52fff xen/include/xen/sched.h
--- a/xen/include/xen/sched.h   Fri Feb 04 18:47:39 2011 +0000
+++ b/xen/include/xen/sched.h   Sun Feb 06 16:07:27 2011 +0000
@@ -607,7 +607,7 @@ struct scheduler *scheduler_get_default(
 struct scheduler *scheduler_get_default(void);
 struct scheduler *scheduler_alloc(unsigned int sched_id, int *perr);
 void scheduler_free(struct scheduler *sched);
-void schedule_cpu_switch(unsigned int cpu, struct cpupool *c);
+int schedule_cpu_switch(unsigned int cpu, struct cpupool *c);
 void vcpu_force_reschedule(struct vcpu *v);
 int cpu_disable_scheduler(unsigned int cpu);
 int vcpu_set_affinity(struct vcpu *v, cpumask_t *affinity);

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