Currently, xenstore clients default to socket communication mode and only
fallback to xenbus if the former is not present. This is a reasonable choice
for both normal hosts (Dom0) and normal VMs (DomU), but it would cause troubles
for SDK/DDK VMs which are playing both host and VM roles. In such VMs, xenstore
clients sometimes need to talk with the xenstored running inside the VM as a
Dom0 client via socket, and sometimes need to talk with the xenstored running
on the real host as a DomU client via xenbus (e.g. as guest agent to report
information back to the real host). With current design, the xenstore clients
in a SDK/DDK VM will always talk to its own xenstored running inside the VM,
and there is no option for us to enforce xenbus communication when necessary.
In this patch, we add an extra flag XS_OPEN_XENBUSONLY (and also a command line
option "-b") corresponding to the current XS_OPEN_SOCKETONLY flag (and the "-s"
option). The algorithm of choosing communication method becomes:
* As before, XENSTORED_PATH environment variable still has the highest priority
over any other options
* If XS_OPEN_SOCKETONLY flag is set, xenstore clients will always use socket
communication and will not try xenbus communication even if socket
communication is not feasible
* If XS_OPEN_XENBUSONLY flag is set, xenstore clients will always use xenbus
communication and will not try socket communication even if xenbus
communication is not feasible
* If both options are unset or both options are set, socket communication will
have the higher priority, and xenbus communication will take place only when
the socket communication is not feasible.
To avoid having to add these switches everywhere, three environment variables
of the same name i.e. "XS_OPEN_XXXONLY" are added and will have the same effect
(in addition to) as passing explicit flags/options to the xs_open primitive if
not empty.
Signed-off-by: Zheng Li <zheng.li@xxxxxxxxxxxxx>
----
diff --git a/tools/python/xen/lowlevel/xs/xs.c
b/tools/python/xen/lowlevel/xs/xs.c
--- a/tools/python/xen/lowlevel/xs/xs.c
+++ b/tools/python/xen/lowlevel/xs/xs.c
@@ -898,15 +898,21 @@ fail:
static int
xshandle_init(XsHandle *self, PyObject *args, PyObject *kwds)
{
- static char *kwd_spec[] = { "readonly", NULL };
- static char *arg_spec = "|i";
- int readonly = 0;
+ static char *kwd_spec[] = { "readonly", "socket", "xenbus", NULL };
+ static char *arg_spec = "|iii";
+ int readonly = 0, socket = 0, xenbus = 0;
+ unsigned long flags = 0;
if (!PyArg_ParseTupleAndKeywords(args, kwds, arg_spec, kwd_spec,
- &readonly))
+ &readonly, &socket, &xenbus))
goto fail;
- self->xh = (readonly ? xs_daemon_open_readonly() : xs_daemon_open());
+ flags |= (readonly ? XS_OPEN_READONLY : 0);
+ flags |= (socket ? XS_OPEN_SOCKETONLY : 0);
+ flags |= (xenbus ? XS_OPEN_XENBUSONLY : 0);
+
+ self->xh = xs_open(flags);
+
if (!self->xh)
goto fail;
diff --git a/tools/xenstore/xenstore_client.c b/tools/xenstore/xenstore_client.c
--- a/tools/xenstore/xenstore_client.c
+++ b/tools/xenstore/xenstore_client.c
@@ -78,24 +78,24 @@ usage(enum mode mode, int incl_mode, con
errx(1, "Usage: %s <mode> [-h] [...]", progname);
case MODE_read:
mstr = incl_mode ? "read " : "";
- errx(1, "Usage: %s %s[-h] [-p] [-s] key [...]", progname, mstr);
+ errx(1, "Usage: %s %s[-h] [-p] [-s|-b] key [...]", progname, mstr);
case MODE_write:
mstr = incl_mode ? "write " : "";
- errx(1, "Usage: %s %s[-h] [-s] key value [...]", progname, mstr);
+ errx(1, "Usage: %s %s[-h] [-s|-b] key value [...]", progname, mstr);
case MODE_rm:
mstr = incl_mode ? "rm " : "";
- errx(1, "Usage: %s %s[-h] [-s] [-t] key [...]", progname, mstr);
+ errx(1, "Usage: %s %s[-h] [-s|-b] [-t] key [...]", progname, mstr);
case MODE_exists:
mstr = incl_mode ? "exists " : "";
case MODE_list:
mstr = mstr ? : incl_mode ? "list " : "";
- errx(1, "Usage: %s %s[-h] [-p] [-s] key [...]", progname, mstr);
+ errx(1, "Usage: %s %s[-h] [-p] [-s|-b] key [...]", progname, mstr);
case MODE_ls:
mstr = mstr ? : incl_mode ? "ls " : "";
- errx(1, "Usage: %s %s[-h] [-f] [-p] [-s] [path]", progname, mstr);
+ errx(1, "Usage: %s %s[-h] [-f] [-p] [-s|-b] [path]", progname, mstr);
case MODE_chmod:
mstr = incl_mode ? "chmod " : "";
- errx(1, "Usage: %s %s[-h] [-u] [-r] [-s] key <mode [modes...]>",
progname, mstr);
+ errx(1, "Usage: %s %s[-h] [-u] [-r] [-s|-b] key <mode [modes...]>",
progname, mstr);
case MODE_watch:
mstr = incl_mode ? "watch " : "";
errx(1, "Usage: %s %s[-h] [-n NR] key", progname, mstr);
@@ -496,7 +496,8 @@ main(int argc, char **argv)
{
struct xs_handle *xsh;
xs_transaction_t xth = XBT_NULL;
- int ret = 0, socket = 0;
+ int ret = 0;
+ unsigned long flags = 0;
int prefix = 0;
int tidy = 0;
int upto = 0;
@@ -531,6 +532,7 @@ main(int argc, char **argv)
{"help", 0, 0, 'h'},
{"flat", 0, 0, 'f'}, /* MODE_ls */
{"socket", 0, 0, 's'},
+ {"xenbus", 0, 0, 'b'},
{"prefix", 0, 0, 'p'}, /* MODE_read || MODE_list || MODE_ls */
{"tidy", 0, 0, 't'}, /* MODE_rm */
{"upto", 0, 0, 'u'}, /* MODE_chmod */
@@ -539,7 +541,7 @@ main(int argc, char **argv)
{0, 0, 0, 0}
};
- c = getopt_long(argc - switch_argv, argv + switch_argv, "hfspturn:",
+ c = getopt_long(argc - switch_argv, argv + switch_argv, "hfsbpturn:",
long_options, &index);
if (c == -1)
break;
@@ -557,9 +559,12 @@ main(int argc, char **argv)
usage(mode, switch_argv, argv[0]);
}
break;
- case 's':
- socket = 1;
- break;
+ case 's':
+ flags |= XS_OPEN_SOCKETONLY;
+ break;
+ case 'b':
+ flags |= XS_OPEN_XENBUSONLY;
+ break;
case 'p':
if ( mode == MODE_read || mode == MODE_list || mode == MODE_ls )
prefix = 1;
@@ -633,7 +638,7 @@ main(int argc, char **argv)
max_width = ws.ws_col - 2;
}
- xsh = xs_open(socket ? XS_OPEN_SOCKETONLY : 0);
+ xsh = xs_open(flags);
if (xsh == NULL) err(1, "xs_open");
again:
diff --git a/tools/xenstore/xs.c b/tools/xenstore/xs.c
--- a/tools/xenstore/xs.c
+++ b/tools/xenstore/xs.c
@@ -257,12 +257,18 @@ struct xs_handle *xs_open(unsigned long
{
struct xs_handle *xsh = NULL;
- if (flags & XS_OPEN_READONLY)
- xsh = get_handle(xs_daemon_socket_ro(), flags);
- else
- xsh = get_handle(xs_daemon_socket(), flags);
+ flags |= (getenv("XS_OPEN_READONLY") ? XS_OPEN_READONLY : 0);
+ flags |= (getenv("XS_OPEN_SOCKETONLY") ? XS_OPEN_SOCKETONLY : 0);
+ flags |= (getenv("XS_OPEN_XENBUSONLY") ? XS_OPEN_XENBUSONLY : 0);
+
+ if ((flags & XS_OPEN_SOCKETONLY) || !(flags & XS_OPEN_XENBUSONLY)) {
+ if (flags & XS_OPEN_READONLY)
+ xsh = get_handle(xs_daemon_socket_ro(), flags);
+ else
+ xsh = get_handle(xs_daemon_socket(), flags);
+ }
- if (!xsh && !(flags & XS_OPEN_SOCKETONLY))
+ if (!xsh && ((flags & XS_OPEN_XENBUSONLY) || !(flags &
XS_OPEN_SOCKETONLY)))
xsh = get_handle(xs_domain_dev(), flags);
return xsh;
diff --git a/tools/xenstore/xs.h b/tools/xenstore/xs.h
--- a/tools/xenstore/xs.h
+++ b/tools/xenstore/xs.h
@@ -26,6 +26,7 @@
#define XS_OPEN_READONLY 1UL<<0
#define XS_OPEN_SOCKETONLY 1UL<<1
+#define XS_OPEN_XENBUSONLY 1UL<<2
struct xs_handle;
typedef uint32_t xs_transaction_t;
tools/python/xen/lowlevel/xs/xs.c | 16 +++++++++++-----
tools/xenstore/xenstore_client.c | 29 +++++++++++++++++------------
tools/xenstore/xs.c | 16 +++++++++++-----
tools/xenstore/xs.h | 1 +
4 files changed, 40 insertions(+), 22 deletions(-)
xen-unstable-3.patch
Description: Text Data
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