minios: Fix lost events

evtchn_bind_interdomain used to clear any already pending event before
binding a handler, because else the handler may be called before it is
ready. That however leads to missed events, which I had to workaround
for the HVM case.

This changes the semantics of bind_evtchn, and thus of all the
event channel binding functions (bind_virq, evtchn_alloc_unbound,
evtchn_bind_interdomain) into not unmasking the event itself, hence
letting the caller initialize properly before unmasking the port (e.g.
record the port number in an appropriate place).

Signed-off-by: Samuel Thibault <samuel.thibault@eu.citrix.com>

1 files changed, 8 insertions, 12 deletions

diff --git a/extras/mini-os/netfront.c b/extras/mini-os/netfront.c
index 095f55ca15..9b709d9826 100644
--- a/extras/mini-os/netfront.c
+++ b/extras/mini-os/netfront.c
@@ -48,7 +48,7 @@ struct netfront_dev {
     struct netif_rx_front_ring rx;
     grant_ref_t tx_ring_ref;
     grant_ref_t rx_ring_ref;
-    evtchn_port_t evtchn, local_port;
+    evtchn_port_t evtchn;
 
     char *nodename;
     char *backend;
@@ -301,19 +301,14 @@ struct netfront_dev *init_netfront(char *nodename, void (*thenetif_rx)(unsigned
         dev->rx_buffers[i].page = (char*)alloc_page();
     }
 
-    evtchn_alloc_unbound_t op;
-    op.dom = DOMID_SELF;
     snprintf(path, sizeof(path), "%s/backend-id", nodename);
-    dev->dom = op.remote_dom = xenbus_read_integer(path);
-    HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound, &op);
-    clear_evtchn(op.port);        /* Without, handler gets invoked now! */
+    dev->dom = xenbus_read_integer(path);
 #ifdef HAVE_LIBC
     if (thenetif_rx == NETIF_SELECT_RX)
-	dev->local_port = bind_evtchn(op.port, netfront_select_handler, dev);
+        evtchn_alloc_unbound(dev->dom, netfront_select_handler, dev, &dev->evtchn);
     else
 #endif
-	dev->local_port = bind_evtchn(op.port, netfront_handler, dev);
-    dev->evtchn=op.port;
+        evtchn_alloc_unbound(dev->dom, netfront_handler, dev, &dev->evtchn);
 
     txs = (struct netif_tx_sring*) alloc_page();
     rxs = (struct netif_rx_sring *) alloc_page();
@@ -388,9 +383,9 @@ done:
     msg = xenbus_read(XBT_NIL, path, &mac);
 
     if ((dev->backend == NULL) || (mac == NULL)) {
-        struct evtchn_close op = { dev->local_port };
+        struct evtchn_close op = { dev->evtchn };
         printk("%s: backend/mac failed\n", __func__);
-        unbind_evtchn(dev->local_port);
+        unbind_evtchn(dev->evtchn);
         HYPERVISOR_event_channel_op(EVTCHNOP_close, &op);
         return NULL;
     }
@@ -412,6 +407,7 @@ done:
     printk("**************************\n");
 
     init_rx_buffers(dev);
+    unmask_evtchn(dev->evtchn);
 
         /* Special conversion specifier 'hh' needed for __ia64__. Without
            this mini-os panics with 'Unaligned reference'. */
@@ -460,7 +456,7 @@ void shutdown_netfront(struct netfront_dev *dev)
     err = xenbus_printf(XBT_NIL, nodename, "state", "%u", 6);
     xenbus_wait_for_value(path,"6");
 
-    unbind_evtchn(dev->local_port);
+    unbind_evtchn(dev->evtchn);
 
     free(nodename);
     free(dev->backend);