From: kaf24@firebug.cl.cam.ac.uk <kaf24@firebug.cl.cam.ac.uk>
Date: Sun, 11 Jun 2006 18:23:31 +0000 (+0100)
Subject: [XEN] Fix SCHEDOP_poll to work even when event channels are
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~15972^2~16
X-Git-Url: https://dgit.raspbian.org/%22http:/www.example.com/cgi/%22https:/%22bookmarks://%22Dat/%22http:/www.example.com/cgi/%22https:/%22bookmarks:/%22Dat?a=commitdiff_plain;h=6553807e774f9cba77210c203b3393db7f61cd53;p=xen.git

[XEN] Fix SCHEDOP_poll to work even when event channels are
not bound to the polling VCPU.
Signed-off-by: Keir Fraser <keir@xensource.com>
---

diff --git a/xen/common/event_channel.c b/xen/common/event_channel.c
index 5437496622..bad68023f6 100644
--- a/xen/common/event_channel.c
+++ b/xen/common/event_channel.c
@@ -498,14 +498,14 @@ void evtchn_set_pending(struct vcpu *v, int port)
     {
         evtchn_notify(v);
     }
-    else if ( unlikely(test_bit(_VCPUF_blocked, &v->vcpu_flags) &&
-                       !local_event_delivery_is_enabled()) )
+    
+    /* Check if some VCPU might be polling for this event. */
+    if ( unlikely(test_bit(_DOMF_polling, &d->domain_flags)) &&
+         likely(test_and_clear_bit(_DOMF_polling, &d->domain_flags)) )
     {
-        /*
-         * Blocked and masked will usually mean that the VCPU executed 
-         * SCHEDOP_poll. Kick the VCPU in case this port is in its poll list.
-         */
-        vcpu_unblock(v);
+        for_each_vcpu ( d, v )
+            if ( test_and_clear_bit(_VCPUF_polling, &v->vcpu_flags) )
+                vcpu_unblock(v);
     }
 }
 
@@ -801,13 +801,6 @@ long do_event_channel_op(int cmd, XEN_GUEST_HANDLE(void) arg)
 }
 
 
-void evtchn_notify_reserved_port(struct domain *d, int port)
-{
-    struct evtchn *chn = evtchn_from_port(d, port);
-    evtchn_set_pending(d->vcpu[chn->notify_vcpu_id], port);
-}
-
-
 int evtchn_init(struct domain *d)
 {
     spin_lock_init(&d->evtchn_lock);
diff --git a/xen/common/schedule.c b/xen/common/schedule.c
index 670ebe8fa1..49384c7468 100644
--- a/xen/common/schedule.c
+++ b/xen/common/schedule.c
@@ -230,13 +230,12 @@ static long do_poll(struct sched_poll *sched_poll)
     if ( !guest_handle_okay(sched_poll->ports, sched_poll->nr_ports) )
         return -EFAULT;
 
-    /* Ensure that events are disabled: tested by evtchn_set_pending(). */
-    if ( local_event_delivery_is_enabled() )
-        return -EINVAL;
-
+    /* These operations must occur in order. */
     set_bit(_VCPUF_blocked, &v->vcpu_flags);
+    set_bit(_VCPUF_polling, &v->vcpu_flags);
+    set_bit(_DOMF_polling, &v->domain->domain_flags);
 
-    /* Check for events /after/ blocking: avoids wakeup waiting race. */
+    /* Check for events /after/ setting flags: avoids wakeup waiting race. */
     for ( i = 0; i < sched_poll->nr_ports; i++ )
     {
         rc = -EFAULT;
@@ -261,6 +260,7 @@ static long do_poll(struct sched_poll *sched_poll)
     stop_timer(&v->poll_timer);
 
  out:
+    clear_bit(_VCPUF_polling, &v->vcpu_flags);
     clear_bit(_VCPUF_blocked, &v->vcpu_flags);
     return rc;
 }
@@ -596,7 +596,8 @@ static void vcpu_timer_fn(void *data)
 static void poll_timer_fn(void *data)
 {
     struct vcpu *v = data;
-    vcpu_unblock(v);
+    if ( test_and_clear_bit(_VCPUF_polling, &v->vcpu_flags) )
+        vcpu_unblock(v);
 }
 
 /* Initialise the data structures. */
diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index bde06f79e6..70869a51af 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -355,7 +355,7 @@ extern struct domain *domain_list;
  /* Initialization completed. */
 #define _VCPUF_initialised     4
 #define VCPUF_initialised      (1UL<<_VCPUF_initialised)
- /* VCPU is not-runnable */
+ /* VCPU is offline. */
 #define _VCPUF_down            5
 #define VCPUF_down             (1UL<<_VCPUF_down)
  /* NMI callback pending for this VCPU? */
@@ -364,6 +364,9 @@ extern struct domain *domain_list;
  /* Avoid NMI reentry by allowing NMIs to be masked for short periods. */
 #define _VCPUF_nmi_masked      9
 #define VCPUF_nmi_masked       (1UL<<_VCPUF_nmi_masked)
+ /* VCPU is polling a set of event channels (SCHEDOP_poll). */
+#define _VCPUF_polling         10
+#define VCPUF_polling          (1UL<<_VCPUF_polling)
 
 /*
  * Per-domain flags (domain_flags).
@@ -383,6 +386,9 @@ extern struct domain *domain_list;
  /* Domain is being debugged by controller software. */
 #define _DOMF_debugging        4
 #define DOMF_debugging         (1UL<<_DOMF_debugging)
+ /* Are any VCPUs polling event channels (SCHEDOP_poll)? */
+#define _DOMF_polling          5
+#define DOMF_polling           (1UL<<_DOMF_polling)
 
 static inline int vcpu_runnable(struct vcpu *v)
 {