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

[Olaf Hering <olaf@xxxxxxxxx>]

# HG changeset patch
# User Olaf Hering <olaf@xxxxxxxxx>
# 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@xxxxxxxxx>

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"

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