# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1259848243 0
# Node ID aa01a13d750b81e2b816bb0799d124698a7de88d
# Parent 9b6b398464b7bf1afd3f6cbac02e7590b9d1d516
Remus: fall back to xenstore if necessary
This is primarily for pvops until it gets a dedicated suspend
event channel.
Signed-off-by: Brendan Cully <brendan@xxxxxxxxx>
---
tools/python/xen/lowlevel/checkpoint/libcheckpoint.c | 259 +++++++++++--------
1 files changed, 153 insertions(+), 106 deletions(-)
diff -r 9b6b398464b7 -r aa01a13d750b
tools/python/xen/lowlevel/checkpoint/libcheckpoint.c
--- a/tools/python/xen/lowlevel/checkpoint/libcheckpoint.c Thu Dec 03
13:50:14 2009 +0000
+++ b/tools/python/xen/lowlevel/checkpoint/libcheckpoint.c Thu Dec 03
13:50:43 2009 +0000
@@ -20,9 +20,12 @@ static int setup_suspend_evtchn(checkpoi
static int setup_suspend_evtchn(checkpoint_state* s);
static void release_suspend_evtchn(checkpoint_state *s);
static int setup_shutdown_watch(checkpoint_state* s);
-static int check_shutdown_watch(checkpoint_state* s);
+static int check_shutdown(checkpoint_state* s);
static void release_shutdown_watch(checkpoint_state* s);
-static int poll_evtchn(checkpoint_state* s);
+
+static int evtchn_suspend(checkpoint_state* s);
+static int compat_suspend(checkpoint_state* s);
+static int pollfd(checkpoint_state* s, int fd);
static int switch_qemu_logdirty(checkpoint_state* s, int enable);
static int suspend_hvm(checkpoint_state* s);
@@ -118,11 +121,10 @@ int checkpoint_open(checkpoint_state* s,
}
if (s->domtype == dt_pv) {
- if (setup_suspend_evtchn(s) < 0) {
- checkpoint_close(s);
-
- return -1;
- }
+ if (setup_suspend_evtchn(s) < 0) {
+ fprintf(stderr, "WARNING: suspend event channel unavailable, "
+ "falling back to slow xenstore signalling\n");
+ }
} else if (s->domtype == dt_pvhvm) {
checkpoint_close(s);
s->errstr = "PV-on-HVM is unsupported";
@@ -158,7 +160,6 @@ void checkpoint_close(checkpoint_state*
s->domid = 0;
s->fd = -1;
- s->suspend_evtchn = -1;
}
/* we toggle logdirty ourselves around the xc_domain_save call --
@@ -207,38 +208,14 @@ int checkpoint_suspend(checkpoint_state*
fprintf(stderr, "PROF: suspending at %lu.%06lu\n", (unsigned long)tv.tv_sec,
(unsigned long)tv.tv_usec);
- if (s->domtype == dt_hvm) {
- return suspend_hvm(s) < 0 ? 0 : 1;
- }
-
- rc = xc_evtchn_notify(s->xce, s->suspend_evtchn);
- if (rc < 0) {
- snprintf(errbuf, sizeof(errbuf),
- "failed to notify suspend event channel: %d", rc);
- s->errstr = errbuf;
-
- return 0;
- }
-
- do {
- rc = poll_evtchn(s);
- } while (rc >= 0 && rc != s->suspend_evtchn);
- if (rc <= 0) {
- snprintf(errbuf, sizeof(errbuf),
- "failed to receive suspend notification: %d", rc);
- s->errstr = errbuf;
-
- return 0;
- }
- if (xc_evtchn_unmask(s->xce, s->suspend_evtchn) < 0) {
- snprintf(errbuf, sizeof(errbuf),
- "failed to unmask suspend notification channel: %d", rc);
- s->errstr = errbuf;
-
- return 0;
- }
-
- return 1;
+ if (s->suspend_evtchn >= 0)
+ rc = evtchn_suspend(s);
+ else if (s->domtype == dt_hvm)
+ rc = suspend_hvm(s);
+ else
+ rc = compat_suspend(s);
+
+ return rc < 0 ? 0 : 1;
}
/* wait for a suspend to be triggered by another thread */
@@ -368,10 +345,8 @@ static int setup_suspend_evtchn(checkpoi
s->suspend_evtchn = xc_suspend_evtchn_init(s->xch, s->xce, s->domid, port);
if (s->suspend_evtchn < 0) {
- snprintf(errbuf, sizeof(errbuf), "failed to bind suspend event channel");
- s->errstr = errbuf;
-
- return -1;
+ s->errstr = "failed to bind suspend event channel";
+ return -1;
}
fprintf(stderr, "bound to suspend event channel %u:%d as %d\n", s->domid,
port,
@@ -384,9 +359,9 @@ static void release_suspend_evtchn(check
static void release_suspend_evtchn(checkpoint_state *s)
{
/* TODO: teach xen to clean up if port is unbound */
- if (s->xce >= 0 && s->suspend_evtchn > 0) {
+ if (s->xce >= 0 && s->suspend_evtchn >= 0) {
xc_suspend_evtchn_release(s->xce, s->suspend_evtchn);
- s->suspend_evtchn = 0;
+ s->suspend_evtchn = -1;
}
}
@@ -402,81 +377,153 @@ static int setup_shutdown_watch(checkpoi
}
/* watch fires once on registration */
s->watching_shutdown = 1;
- check_shutdown_watch(s);
+ check_shutdown(s);
return 0;
}
-static int check_shutdown_watch(checkpoint_state* s) {
- unsigned int count;
- char **vec;
- char buf[16];
-
- vec = xs_read_watch(s->xsh, &count);
- if (s->watching_shutdown == 1) {
- s->watching_shutdown = 2;
- return 0;
- }
- if (!vec) {
- fprintf(stderr, "empty watch fired\n");
- return 0;
- }
- snprintf(buf, sizeof(buf), "%d", s->domid);
- if (!strcmp(vec[XS_WATCH_TOKEN], buf)) {
- fprintf(stderr, "domain %d shut down\n", s->domid);
- return -1;
- }
-
- return 0;
+/* returns -1 on error or death, 0 if domain is running, 1 if suspended */
+static int check_shutdown(checkpoint_state* s) {
+ unsigned int count;
+ int xsfd;
+ char **vec;
+ char buf[16];
+ xc_dominfo_t info;
+
+ xsfd = xs_fileno(s->xsh);
+
+ /* loop on watch if it fires for another domain */
+ while (1) {
+ if (pollfd(s, xsfd) < 0)
+ return -1;
+
+ vec = xs_read_watch(s->xsh, &count);
+ if (s->watching_shutdown == 1) {
+ s->watching_shutdown = 2;
+ return 0;
+ }
+ if (!vec) {
+ fprintf(stderr, "empty watch fired\n");
+ continue;
+ }
+ snprintf(buf, sizeof(buf), "%d", s->domid);
+ if (!strcmp(vec[XS_WATCH_TOKEN], buf))
+ break;
+ }
+
+ if (xc_domain_getinfo(s->xch, s->domid, 1, &info) != 1
+ || info.domid != s->domid) {
+ snprintf(errbuf, sizeof(errbuf),
+ "error getting info for domain %u", s->domid);
+ s->errstr = errbuf;
+ return -1;
+ }
+ if (!info.shutdown) {
+ snprintf(errbuf, sizeof(errbuf),
+ "domain %u not shut down", s->domid);
+ s->errstr = errbuf;
+ return 0;
+ }
+
+ if (info.shutdown_reason != SHUTDOWN_suspend)
+ return -1;
+
+ return 1;
}
static void release_shutdown_watch(checkpoint_state* s) {
char buf[16];
if (!s->xsh)
- return;
-
+ return;
if (!s->watching_shutdown)
return;
snprintf(buf, sizeof(buf), "%u", s->domid);
if (!xs_unwatch(s->xsh, "@releaseDomain", buf))
fprintf(stderr, "Could not release shutdown watch\n");
-}
-
-/* wrapper around xc_evtchn_pending which detects errors */
-static int poll_evtchn(checkpoint_state* s)
-{
- int fd, xsfd, maxfd;
- fd_set rfds, efds;
- struct timeval tv;
- int rc;
-
- fd = xc_evtchn_fd(s->xce);
- xsfd = xs_fileno(s->xsh);
- maxfd = fd > xsfd ? fd : xsfd;
- FD_ZERO(&rfds);
- FD_ZERO(&efds);
- FD_SET(fd, &rfds);
- FD_SET(xsfd, &rfds);
- FD_SET(fd, &efds);
- FD_SET(xsfd, &efds);
-
- /* give it 500 ms to respond */
- tv.tv_sec = 0;
- tv.tv_usec = 500000;
-
- rc = select(maxfd + 1, &rfds, NULL, &efds, &tv);
- if (rc < 0)
- fprintf(stderr, "error polling event channel: %s\n", strerror(errno));
- else if (!rc)
- fprintf(stderr, "timeout waiting for event channel\n");
- else if (FD_ISSET(fd, &rfds))
- return xc_evtchn_pending(s->xce);
- else if (FD_ISSET(xsfd, &rfds))
- return check_shutdown_watch(s);
-
- return -1;
+
+ s->watching_shutdown = 0;
+}
+
+static int evtchn_suspend(checkpoint_state* s)
+{
+ int rc;
+
+ rc = xc_evtchn_notify(s->xce, s->suspend_evtchn);
+ if (rc < 0) {
+ snprintf(errbuf, sizeof(errbuf),
+ "failed to notify suspend event channel: %d", rc);
+ s->errstr = errbuf;
+
+ return -1;
+ }
+
+ do
+ if (!(rc = pollfd(s, xc_evtchn_fd(s->xce))))
+ rc = xc_evtchn_pending(s->xce);
+ while (rc >= 0 && rc != s->suspend_evtchn);
+ if (rc <= 0)
+ return -1;
+
+ if (xc_evtchn_unmask(s->xce, s->suspend_evtchn) < 0) {
+ snprintf(errbuf, sizeof(errbuf),
+ "failed to unmask suspend notification channel: %d", rc);
+ s->errstr = errbuf;
+
+ return -1;
+ }
+
+ return 0;
+}
+
+/* suspend through xenstore if suspend event channel is unavailable */
+static int compat_suspend(checkpoint_state* s)
+{
+ char path[128];
+
+ sprintf(path, "/local/domain/%u/control/shutdown", s->domid);
+
+ if (!xs_write(s->xsh, XBT_NULL, path, "suspend", 7)) {
+ s->errstr = "error signalling qemu logdirty";
+ return -1;
+ }
+
+ if (check_shutdown(s) != 1)
+ return -1;
+
+ return 0;
+}
+
+/* returns -1 if fd does not become readable within timeout */
+static int pollfd(checkpoint_state* s, int fd)
+{
+ fd_set rfds;
+ struct timeval tv;
+ int rc;
+
+ FD_ZERO(&rfds);
+ FD_SET(fd, &rfds);
+
+ tv.tv_sec = 0;
+ tv.tv_usec = 500000;
+
+ rc = select(fd + 1, &rfds, NULL, NULL, &tv);
+
+ if (rc < 0) {
+ snprintf(errbuf, sizeof(errbuf),
+ "error polling fd: %s", strerror(errno));
+ s->errstr = errbuf;
+ } else if (!rc) {
+ snprintf(errbuf, sizeof(errbuf), "timeout polling fd");
+ s->errstr = errbuf;
+ } else if (! FD_ISSET(fd, &rfds)) {
+ snprintf(errbuf, sizeof(errbuf), "unknown error polling fd");
+ s->errstr = errbuf;
+ } else
+ return 0;
+
+ return -1;
}
/* adapted from the eponymous function in xc_save */
@@ -537,7 +584,7 @@ static int suspend_hvm(checkpoint_state
}
fprintf(stderr, "suspend hypercall returned %d\n", rc);
- if (check_shutdown_watch(s) >= 0)
+ if (check_shutdown(s) != 1)
return -1;
rc = suspend_qemu(s);
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