Add a simple mechanism to poll for a change in the property value

2 files changed, 89 insertions, 20 deletions

diff --git a/sys/dev/pv/xenstore.c b/sys/dev/pv/xenstore.c
index 1d5f5f4cab2..b55e934dfe4 100644
--- a/sys/dev/pv/xenstore.c
+++ b/sys/dev/pv/xenstore.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: xenstore.c,v 1.34 2016/12/07 15:18:02 mikeb Exp $	*/
+/*	$OpenBSD: xenstore.c,v 1.35 2016/12/07 15:21:04 mikeb Exp $	*/
 
 /*
  * Copyright (c) 2015 Mike Belopuhov
@@ -936,6 +936,62 @@ xs_setprop(void *xsc, const char *path, const char *property, char *value,
 }
 
 int
+xs_cmpprop(void *xsc, const char *path, const char *property, const char *value,
+    int *result)
+{
+	struct xen_softc *sc = xsc;
+	struct xs_transaction xst;
+	struct iovec *iovp = NULL;
+	char key[256];
+	int error, ret, iov_cnt = 0;
+
+	if (!property)
+		return (EINVAL);
+
+	memset(&xst, 0, sizeof(xst));
+	xst.xst_id = 0;
+	xst.xst_cookie = sc->sc_xs;
+	if (cold)
+		xst.xst_flags = XST_POLL;
+
+	if (path)
+		ret = snprintf(key, sizeof(key), "%s/%s", path, property);
+	else
+		ret = snprintf(key, sizeof(key), "%s", property);
+	if (ret == -1 || ret >= sizeof(key))
+		return (EINVAL);
+
+	if ((error = xs_cmd(&xst, XS_READ, key, &iovp, &iov_cnt)) != 0)
+		return (error);
+
+	if (*result)
+		*result = strcmp(value, (char *)iovp->iov_base);
+
+	xs_resfree(&xst, iovp, iov_cnt);
+
+	return (0);
+}
+
+int
+xs_await_transition(void *xsc, const char *path, const char *property,
+    const char *value, int timo)
+{
+	struct xen_softc *sc = xsc;
+	int error, res;
+
+	do {
+		error = xs_cmpprop(xsc, path, property, value, &res);
+		if (error)
+			return (error);
+		if (timo && --timo == 0)
+			return (ETIMEDOUT);
+		xs_poll(sc->sc_xs, cold);
+	} while (res != 0);
+
+	return (0);
+}
+
+int
 xs_kvop(void *xsc, int op, char *key, char *value, size_t valuelen)
 {
 	struct xen_softc *sc = xsc;
diff --git a/sys/dev/pv/xenvar.h b/sys/dev/pv/xenvar.h
index 8378d1db0a2..5d7bf147a7c 100644
--- a/sys/dev/pv/xenvar.h
+++ b/sys/dev/pv/xenvar.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: xenvar.h,v 1.41 2016/11/29 14:55:04 mikeb Exp $	*/
+/*	$OpenBSD: xenvar.h,v 1.42 2016/12/07 15:21:04 mikeb Exp $	*/
 
 /*
  * Copyright (c) 2015 Mike Belopuhov
@@ -27,6 +27,24 @@
 #define DPRINTF(x...)
 #endif
 
+static inline void
+clear_bit(u_int b, volatile void *p)
+{
+	atomic_clearbits_int(((volatile u_int *)p) + (b >> 5), 1 << (b & 0x1f));
+}
+
+static inline void
+set_bit(u_int b, volatile void *p)
+{
+	atomic_setbits_int(((volatile u_int *)p) + (b >> 5), 1 << (b & 0x1f));
+}
+
+static inline int
+test_bit(u_int b, volatile void *p)
+{
+	return !!(((volatile u_int *)p)[b >> 5] & (1 << (b & 0x1f)));
+}
+
 struct xen_intsrc {
 	SLIST_ENTRY(xen_intsrc)	 xi_entry;
 	struct evcount		 xi_evcnt;
@@ -153,24 +171,6 @@ struct xs_transaction {
 	void			*xst_cookie;
 };
 
-static __inline void
-clear_bit(u_int b, volatile void *p)
-{
-	atomic_clearbits_int(((volatile u_int *)p) + (b >> 5), 1 << (b & 0x1f));
-}
-
-static __inline void
-set_bit(u_int b, volatile void *p)
-{
-	atomic_setbits_int(((volatile u_int *)p) + (b >> 5), 1 << (b & 0x1f));
-}
-
-static __inline int
-test_bit(u_int b, volatile void *p)
-{
-	return !!(((volatile u_int *)p)[b >> 5] & (1 << (b & 0x1f)));
-}
-
 int	xs_cmd(struct xs_transaction *, int, const char *, struct iovec **,
 	    int *);
 void	xs_resfree(struct xs_transaction *, struct iovec *, int);
@@ -180,4 +180,17 @@ int	xs_getprop(void *, const char *, const char *, char *, int);
 int	xs_setprop(void *, const char *, const char *, char *, int);
 int	xs_kvop(void *, int, char *, char *, size_t);
 
+#define XEN_STATE_UNKNOWN	"0"
+#define XEN_STATE_INITIALIZING	"1"
+#define XEN_STATE_INITWAIT	"2"
+#define XEN_STATE_INITIALIZED	"3"
+#define XEN_STATE_CONNECTED	"4"
+#define XEN_STATE_CLOSING	"5"
+#define XEN_STATE_CLOSED	"6"
+#define XEN_STATE_RECONFIGURING	"7"
+#define XEN_STATE_RECONFIGURED	"8"
+
+int	xs_await_transition(void *, const char *, const char *,
+	    const char *, int);
+
 #endif	/* _DEV_PV_XENVAR_H_ */