[Xen-changelog] [xen-3.0-testing] [XEN] Fix SCHEDOP_poll to work even when event channels are

[Xen patchbot-3.0-testing <patchbot-3.0-testing@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User kaf24@xxxxxxxxxxxxxxxxxxxx
# Node ID 5461e2e86e989375b707f25bf93d3d4074b80920
# Parent  df221e310e2b4f162167147aa3d7656af3969417
[XEN] Fix SCHEDOP_poll to work even when event channels are
not bound to the polling VCPU.
Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>
xen-unstable changeset:   10319:aced0ee216aa474c7883efa56eb918d4fe7d6098
xen-unstable date:        Sun Jun 11 19:23:31 2006 +0100
---
 xen/common/event_channel.c |   16 ++++++++--------
 xen/common/schedule.c      |   15 ++++++++-------
 xen/include/xen/sched.h    |    8 +++++++-
 3 files changed, 23 insertions(+), 16 deletions(-)

diff -r df221e310e2b -r 5461e2e86e98 xen/common/event_channel.c
--- a/xen/common/event_channel.c        Sun Jun 11 10:10:59 2006 +0100
+++ b/xen/common/event_channel.c        Sun Jun 11 19:28:57 2006 +0100
@@ -460,14 +460,14 @@ void evtchn_set_pending(struct vcpu *v, 
     {
         evtchn_notify(v);
     }
-    else if ( unlikely(test_bit(_VCPUF_blocked, &v->vcpu_flags) &&
-                       v->vcpu_info->evtchn_upcall_mask) )
-    {
-        /*
-         * 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);
+
+    /* 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)) )
+    {
+        for_each_vcpu ( d, v )
+            if ( test_and_clear_bit(_VCPUF_polling, &v->vcpu_flags) )
+                vcpu_unblock(v);
     }
 }
 
diff -r df221e310e2b -r 5461e2e86e98 xen/common/schedule.c
--- a/xen/common/schedule.c     Sun Jun 11 10:10:59 2006 +0100
+++ b/xen/common/schedule.c     Sun Jun 11 19:28:57 2006 +0100
@@ -297,13 +297,12 @@ static long do_poll(struct sched_poll *s
     if ( !guest_handle_okay(sched_poll->ports, sched_poll->nr_ports) )
         return -EFAULT;
 
-    /* Ensure that upcalls are disabled: tested by evtchn_set_pending(). */
-    if ( !v->vcpu_info->evtchn_upcall_mask )
-        return -EINVAL;
-
+    /* These operations must occur in order. */
     set_bit(_VCPUF_blocked, &v->vcpu_flags);
-
-    /* Check for events /after/ blocking: avoids wakeup waiting race. */
+    set_bit(_VCPUF_polling, &v->vcpu_flags);
+    set_bit(_DOMF_polling, &v->domain->domain_flags);
+
+    /* Check for events /after/ setting flags: avoids wakeup waiting race. */
     for ( i = 0; i < sched_poll->nr_ports; i++ )
     {
         rc = -EFAULT;
@@ -328,6 +327,7 @@ static long do_poll(struct sched_poll *s
     stop_timer(&v->poll_timer);
 
  out:
+    clear_bit(_VCPUF_polling, &v->vcpu_flags);
     clear_bit(_VCPUF_blocked, &v->vcpu_flags);
     return rc;
 }
@@ -637,7 +637,8 @@ static void poll_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 -r df221e310e2b -r 5461e2e86e98 xen/include/xen/sched.h
--- a/xen/include/xen/sched.h   Sun Jun 11 10:10:59 2006 +0100
+++ b/xen/include/xen/sched.h   Sun Jun 11 19:28:57 2006 +0100
@@ -356,7 +356,7 @@ 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? */
@@ -365,6 +365,9 @@ 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).
@@ -384,6 +387,9 @@ 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)
 {

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