[PATCH 02/16] xen: sched: add .init_pdata hook to the scheduler interface

[Dario Faggioli <dario.faggioli@citrix.com>]

with the purpose of decoupling the allocation phase and
the initialization one, for per-pCPU data of the schedulers.

This makes it possible to perform the initialization later
in the pCPU bringup/assignement process, when more information
(for instance, the host CPU topology) are available. This,
for now, is important only for Credit2, but it can well be
useful to other schedulers.

Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
---
Cc: George Dunlap <george.dunlap@eu.citrix.com>
Cc: Juergen Gross <jgross@suse.com>
---
Changes from v1:
 * in schedule_cpu_switch(), call to init_pdata() moved up,
   close to the call to alloc_pdata() (for consistency with
   other call sites) and prototype slightly changed.
---
During v1 review, it was agreed to add ASSERTS() and comments
to clarify the use of schedule_cpu_switch(). This can't be
found here, but only because it has happened in another patch.
---
 xen/common/schedule.c      |    7 +++++++
 xen/include/xen/sched-if.h |    1 +
 2 files changed, 8 insertions(+)

diff --git a/xen/common/schedule.c b/xen/common/schedule.c
index e57b659..0627eb5 100644
--- a/xen/common/schedule.c
+++ b/xen/common/schedule.c
@@ -1517,10 +1517,15 @@ static int cpu_schedule_callback(
     struct notifier_block *nfb, unsigned long action, void *hcpu)
 {
     unsigned int cpu = (unsigned long)hcpu;
+    struct scheduler *sched = per_cpu(scheduler, cpu);
+    struct schedule_data *sd = &per_cpu(schedule_data, cpu);
     int rc = 0;
 
     switch ( action )
     {
+    case CPU_STARTING:
+        SCHED_OP(sched, init_pdata, sd->sched_priv, cpu);
+        break;
     case CPU_UP_PREPARE:
         rc = cpu_schedule_up(cpu);
         break;
@@ -1597,6 +1602,7 @@ void __init scheduler_init(void)
     if ( ops.alloc_pdata &&
          !(this_cpu(schedule_data).sched_priv = ops.alloc_pdata(&ops, 0)) )
         BUG();
+    SCHED_OP(&ops, init_pdata, this_cpu(schedule_data).sched_priv, 0);
 }
 
 /*
@@ -1640,6 +1646,7 @@ int schedule_cpu_switch(unsigned int cpu, struct cpupool *c)
     ppriv = SCHED_OP(new_ops, alloc_pdata, cpu);
     if ( ppriv == NULL )
         return -ENOMEM;
+    SCHED_OP(new_ops, init_pdata, ppriv, cpu);
     vpriv = SCHED_OP(new_ops, alloc_vdata, idle, idle->domain->sched_priv);
     if ( vpriv == NULL )
     {
diff --git a/xen/include/xen/sched-if.h b/xen/include/xen/sched-if.h
index 825f1ad..70c08c6 100644
--- a/xen/include/xen/sched-if.h
+++ b/xen/include/xen/sched-if.h
@@ -133,6 +133,7 @@ struct scheduler {
                                     void *);
     void         (*free_pdata)     (const struct scheduler *, void *, int);
     void *       (*alloc_pdata)    (const struct scheduler *, int);
+    void         (*init_pdata)     (const struct scheduler *, void *, int);
     void         (*free_domdata)   (const struct scheduler *, void *);
     void *       (*alloc_domdata)  (const struct scheduler *, struct domain *);
 


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