xenstored now supports multiple concurrent transactions per

connection, plus interleaving of transactional and
non-transactional accesses. A transaction identifier is added
to the xsd_sockmsg header structure (0 means 'not in context
of a transaction'). The user and kernel xs interfaces accept
a pointer to a transaction handle where appropriate --
currently this is directly cast to an integer identifier in
the client library / kernel driver, but will allow for keeping
extra dynamic client-side state in future if we need to.

The transaction mutex has now gone. It's replaced with a
read-write mutex, but this is only acquired for exclusive
access during suspend/resume, to ensure there are no in-progress
transactions.

Signed-off-by: Keir Fraser <keir@xensource.com>

1 files changed, 30 insertions, 0 deletions

diff --git a/tools/xenstore/utils.h b/tools/xenstore/utils.h
index 5fbfceeaa9..df82c1c5ef 100644
--- a/tools/xenstore/utils.h
+++ b/tools/xenstore/utils.h
@@ -55,4 +55,34 @@ void xprintf(const char *fmt, ...);
 #define dprintf(_fmt, _args...) ((void)0)
 #endif
 
+/*
+ * Mux errno values onto returned pointers.
+ */
+
+static inline void *ERR_PTR(long error)
+{
+	return (void *)error;
+}
+
+static inline long PTR_ERR(const void *ptr)
+{
+	return (long)ptr;
+}
+
+static inline long IS_ERR(const void *ptr)
+{
+	return ((unsigned long)ptr > (unsigned long)-1000L);
+}
+
+
 #endif /* _UTILS_H */
+
+/*
+ * Local variables:
+ *  c-file-style: "linux"
+ *  indent-tabs-mode: t
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ *  tab-width: 8
+ * End:
+ */