[PATCH] xenstored: allow guests to shutdown all of its watches using XS_RESET_WATCHES

[Olaf Hering <olaf@aepfle.de>]

# HG changeset patch
# User Olaf Hering <olaf@aepfle.de>
# Date 1313396962 -7200
# Node ID 4b483f4fa715566847b57f4c20908e5c3d38b5a2
# Parent  1f08b380d4386cdd6714786a9163e5f51aecab5d
xenstored: allow guests to shutdown all of its watches using XS_RESET_WATCHES

During kexec all old watches have to be removed, otherwise the new
kernel will receive unexpected events. Allow a guest to reset itself and
cleanup all of its watches.

Add a new XS_RESET_WATCHES command to do the reset on behalf of the guest.

Signed-off-by: Olaf Hering <olaf@aepfle.de>

diff -r 1f08b380d438 -r 4b483f4fa715 docs/misc/xenstore.txt
--- a/docs/misc/xenstore.txt
+++ b/docs/misc/xenstore.txt
@@ -217,6 +217,9 @@ WATCH_EVENT					<epath>|<token>|
 
 UNWATCH			<wpath>|<token>|?
 
+RESET_WATCHES		<dummy>
+	Reset all watches and transactions of the caller.
+
 ---------- Transactions ----------
 
 TRANSACTION_START	|			<transid>|
diff -r 1f08b380d438 -r 4b483f4fa715 tools/xenstore/xenstored_core.c
--- a/tools/xenstore/xenstored_core.c
+++ b/tools/xenstore/xenstored_core.c
@@ -120,6 +120,7 @@ static char *sockmsg_string(enum xsd_soc
 	case XS_IS_DOMAIN_INTRODUCED: return "XS_IS_DOMAIN_INTRODUCED";
 	case XS_RESUME: return "RESUME";
 	case XS_SET_TARGET: return "SET_TARGET";
+	case XS_RESET_WATCHES: return "RESET_WATCHES";
 	default:
 		return "**UNKNOWN**";
 	}
@@ -1242,6 +1243,10 @@ static void process_message(struct conne
 		do_set_target(conn, in);
 		break;
 
+	case XS_RESET_WATCHES:
+		do_reset_watches(conn);
+		break;
+
 	default:
 		eprintf("Client unknown operation %i", in->hdr.msg.type);
 		send_error(conn, ENOSYS);
diff -r 1f08b380d438 -r 4b483f4fa715 tools/xenstore/xenstored_domain.c
--- a/tools/xenstore/xenstored_domain.c
+++ b/tools/xenstore/xenstored_domain.c
@@ -537,6 +537,20 @@ void do_is_domain_introduced(struct conn
 	send_reply(conn, XS_IS_DOMAIN_INTRODUCED, result ? "T" : "F", 2);
 }
 
+/* Allow guest to reset all watches */
+void do_reset_watches(struct connection *conn)
+{
+	if (!conn->can_write) {
+		send_error(conn, EACCES);
+		return;
+	}
+
+	conn_delete_all_watches(conn);
+	conn_delete_all_transactions(conn);
+
+	send_ack(conn, XS_RESET_WATCHES);
+}
+
 static int close_xc_handle(void *_handle)
 {
 	xc_interface_close(*(xc_interface**)_handle);
diff -r 1f08b380d438 -r 4b483f4fa715 tools/xenstore/xenstored_domain.h
--- a/tools/xenstore/xenstored_domain.h
+++ b/tools/xenstore/xenstored_domain.h
@@ -40,6 +40,9 @@ void do_set_target(struct connection *co
 /* domid */
 void do_get_domain_path(struct connection *conn, const char *domid_str);
 
+/* Allow guest to reset all watches */
+void do_reset_watches(struct connection *conn);
+
 void domain_init(void);
 
 /* Returns the implicit path of a connection (only domains have this) */
diff -r 1f08b380d438 -r 4b483f4fa715 xen/include/public/io/xs_wire.h
--- a/xen/include/public/io/xs_wire.h
+++ b/xen/include/public/io/xs_wire.h
@@ -48,7 +48,8 @@ enum xsd_sockmsg_type
     XS_IS_DOMAIN_INTRODUCED,
     XS_RESUME,
     XS_SET_TARGET,
-    XS_RESTRICT
+    XS_RESTRICT,
+    XS_RESET_WATCHES
 };
 
 #define XS_WRITE_NONE "NONE"