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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH 15/19] libxl: suspend: Async xenstore pvcontrol wait
When negotiating guest suspend via the xenstore pvcontrol protocol
(ie when the guest does NOT support the evtchn fast suspend protocol):
Replace the use of loops and usleep with a call to libxl__xswait.
Also, replace the xenstore transaction loop with one using
libxl__xs_transaction_start et al.
There is not intended to be any semantic change, other than to make
the algorithm properly asynchronous.
Signed-off-by: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
CC: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
CC: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
tools/libxl/libxl_dom.c | 93 ++++++++++++++++++++++++++----------------
tools/libxl/libxl_internal.h | 1 +
2 files changed, 59 insertions(+), 35 deletions(-)
diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
index 8aceba9..dde7e33 100644
--- a/tools/libxl/libxl_dom.c
+++ b/tools/libxl/libxl_dom.c
@@ -1028,6 +1028,8 @@ static void domain_suspend_common_wait_guest(libxl__egc
*egc,
libxl__domain_suspend_state *dss);
static void domain_suspend_common_guest_suspended(libxl__egc *egc,
libxl__domain_suspend_state *dss);
+static void domain_suspend_common_pvcontrol_suspending(libxl__egc *egc,
+ libxl__xswait_state *xswa, int rc, const char *state);
static void domain_suspend_common_failed(libxl__egc *egc,
libxl__domain_suspend_state *dss);
static void domain_suspend_common_done(libxl__egc *egc,
@@ -1047,10 +1049,6 @@ static void domain_suspend_callback_common(libxl__egc
*egc,
STATE_AO_GC(dss->ao);
unsigned long hvm_s_state = 0, hvm_pvdrv = 0;
int ret;
- char *state = "suspend";
- int watchdog;
- xs_transaction_t t;
- int rc;
/* Convenience aliases */
const uint32_t domid = dss->domid;
@@ -1096,59 +1094,81 @@ static void domain_suspend_callback_common(libxl__egc
*egc,
libxl__domain_pvcontrol_write(gc, XBT_NULL, domid, "suspend");
- LOG(DEBUG, "wait for the guest to acknowledge suspend request");
- watchdog = 60;
- while (!domain_suspend_pvcontrol_acked(state) && watchdog > 0) {
- usleep(100000);
+ dss->pvcontrol.path = libxl__domain_pvcontrol_xspath(gc, domid);
+ if (!dss->pvcontrol.path) goto err;
- state = libxl__domain_pvcontrol_read(gc, XBT_NULL, domid);
+ dss->pvcontrol.ao = ao;
+ dss->pvcontrol.what = "guest acknowledgement of suspend request";
+ dss->pvcontrol.timeout_ms = 60 * 1000;
+ dss->pvcontrol.callback = domain_suspend_common_pvcontrol_suspending;
+ libxl__xswait_start(gc, &dss->pvcontrol);
+ return;
- watchdog--;
- }
+ err:
+ domain_suspend_common_failed(egc, dss);
+}
- /*
- * Guest appears to not be responding. Cancel the suspend
- * request.
- *
- * We re-read the suspend node and clear it within a
- * transaction in order to handle the case where we race
- * against the guest catching up and acknowledging the request
- * at the last minute.
- */
- if (!domain_suspend_pvcontrol_acked(state)) {
- LOG(ERROR, "guest didn't acknowledge suspend, cancelling request");
+static void domain_suspend_common_pvcontrol_suspending(libxl__egc *egc,
+ libxl__xswait_state *xswa, int rc, const char *state)
+{
+ libxl__domain_suspend_state *dss = CONTAINER_OF(xswa, *dss, pvcontrol);
+ STATE_AO_GC(dss->ao);
+ xs_transaction_t t = 0;
+
+ if (!rc && !domain_suspend_pvcontrol_acked(state))
+ /* keep waiting */
+ return;
+
+ libxl__xswait_stop(gc, &dss->pvcontrol);
+
+ if (rc == ERROR_TIMEDOUT) {
+ /*
+ * Guest appears to not be responding. Cancel the suspend
+ * request.
+ *
+ * We re-read the suspend node and clear it within a
+ * transaction in order to handle the case where we race
+ * against the guest catching up and acknowledging the request
+ * at the last minute.
+ */
for (;;) {
rc = libxl__xs_transaction_start(gc, &t);
if (rc) goto err;
- state = libxl__domain_pvcontrol_read(gc, t, domid);
+ rc = libxl__xs_read_checked(gc, t, xswa->path, &state);
+ if (rc) goto err;
+
+ if (domain_suspend_pvcontrol_acked(state))
+ break;
- if (!domain_suspend_pvcontrol_acked(state))
- libxl__domain_pvcontrol_write(gc, t, domid, "");
+ rc = libxl__xs_write_checked(gc, t, xswa->path, "");
+ if (rc) goto err;
rc = libxl__xs_transaction_commit(gc, &t);
- if (!rc) break;
+ if (!rc) {
+ LOG(ERROR,
+ "guest didn't acknowledge suspend, cancelling request");
+ goto err;
+ }
if (rc<0) goto err;
}
- }
-
- /*
- * Final check for guest acknowledgement. The guest may have
- * acknowledged while we were cancelling the request in which
- * case we lost the race while cancelling and should continue.
- */
- if (!domain_suspend_pvcontrol_acked(state)) {
- LOG(ERROR, "guest didn't acknowledge suspend, request cancelled");
+ } else if (rc) {
+ /* some error in xswait's read of xenstore, already logged */
goto err;
}
+ assert(domain_suspend_pvcontrol_acked(state));
LOG(DEBUG, "guest acknowledged suspend request");
+
+ libxl__xs_transaction_abort(gc, &t);
dss->guest_responded = 1;
domain_suspend_common_wait_guest(egc,dss);
return;
err:
+ libxl__xs_transaction_abort(gc, &t);
domain_suspend_common_failed(egc, dss);
+ return;
}
static void domain_suspend_common_wait_guest(libxl__egc *egc,
@@ -1215,6 +1235,8 @@ static void domain_suspend_common_done(libxl__egc *egc,
libxl__domain_suspend_state *dss,
bool ok)
{
+ EGC_GC;
+ assert(!libxl__xswait_inuse(&dss->pvcontrol));
dss->callback_common_done(egc, dss, ok);
}
@@ -1400,6 +1422,7 @@ void libxl__domain_suspend(libxl__egc *egc,
libxl__domain_suspend_state *dss)
&dss->shs.callbacks.save.a;
logdirty_init(&dss->logdirty);
+ libxl__xswait_init(&dss->pvcontrol);
switch (type) {
case LIBXL_DOMAIN_TYPE_HVM: {
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 97dbd8e..5ac02cb 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -2422,6 +2422,7 @@ struct libxl__domain_suspend_state {
int hvm;
int xcflags;
int guest_responded;
+ libxl__xswait_state pvcontrol;
const char *dm_savefile;
int interval; /* checkpoint interval (for Remus) */
libxl__save_helper_state shs;
--
1.7.10.4
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