On 2014/10/4 1:47, Dr. David Alan Gilbert (git) wrote:
From: "Dr. David Alan Gilbert" <dgilb...@redhat.com>
Open a return path, and handle messages that are received upon it.
Signed-off-by: Dr. David Alan Gilbert <dgilb...@redhat.com>
---
include/migration/migration.h | 10 +++
migration.c | 181 +++++++++++++++++++++++++++++++++++++++++-
2 files changed, 190 insertions(+), 1 deletion(-)
diff --git a/include/migration/migration.h b/include/migration/migration.h
index 12e640d..b87c289 100644
--- a/include/migration/migration.h
+++ b/include/migration/migration.h
@@ -47,6 +47,14 @@ enum mig_rpcomm_cmd {
MIG_RPCOMM_ACK, /* data (seq: be32 ) */
MIG_RPCOMM_AFTERLASTVALID
};
+
+/* Source side RP state */
+struct MigrationRetPathState {
+ uint32_t latest_ack;
+ QemuThread rp_thread;
+ bool error;
+};
+
typedef struct MigrationState MigrationState;
/* State for the incoming migration */
@@ -69,9 +77,11 @@ struct MigrationState
QemuThread thread;
QEMUBH *cleanup_bh;
QEMUFile *file;
+ QEMUFile *return_path;
int state;
MigrationParams params;
+ struct MigrationRetPathState rp_state;
double mbps;
int64_t total_time;
int64_t downtime;
diff --git a/migration.c b/migration.c
index 5ba8f3e..ee6db1d 100644
--- a/migration.c
+++ b/migration.c
@@ -246,6 +246,23 @@ MigrationCapabilityStatusList
*qmp_query_migrate_capabilities(Error **errp)
return head;
}
+/*
+ * Return true if we're already in the middle of a migration
+ * (i.e. any of the active or setup states)
+ */
+static bool migration_already_active(MigrationState *ms)
+{
+ switch (ms->state) {
+ case MIG_STATE_ACTIVE:
+ case MIG_STATE_SETUP:
+ return true;
+
+ default:
+ return false;
+
+ }
+}
+
static void get_xbzrle_cache_stats(MigrationInfo *info)
{
if (migrate_use_xbzrle()) {
@@ -371,6 +388,21 @@ static void migrate_set_state(MigrationState *s, int
old_state, int new_state)
}
}
+static void migrate_fd_cleanup_src_rp(MigrationState *ms)
+{
+ QEMUFile *rp = ms->return_path;
+
+ /*
+ * When stuff goes wrong (e.g. failing destination) on the rp, it can get
+ * cleaned up from a few threads; make sure not to do it twice in parallel
+ */
+ rp = atomic_cmpxchg(&ms->return_path, rp, NULL);
+ if (rp) {
+ DPRINTF("cleaning up return path\n");
+ qemu_fclose(rp);
+ }
+}
+
static void migrate_fd_cleanup(void *opaque)
{
MigrationState *s = opaque;
@@ -378,6 +410,8 @@ static void migrate_fd_cleanup(void *opaque)
qemu_bh_delete(s->cleanup_bh);
s->cleanup_bh = NULL;
+ migrate_fd_cleanup_src_rp(s);
+
if (s->file) {
trace_migrate_fd_cleanup();
qemu_mutex_unlock_iothread();
@@ -414,6 +448,11 @@ static void migrate_fd_cancel(MigrationState *s)
int old_state ;
trace_migrate_fd_cancel();
+ if (s->return_path) {
+ /* shutdown the rp socket, so causing the rp thread to shutdown */
+ qemu_file_shutdown(s->return_path);
+ }
+
do {
old_state = s->state;
if (old_state != MIG_STATE_SETUP && old_state != MIG_STATE_ACTIVE) {
@@ -655,8 +694,148 @@ int64_t migrate_xbzrle_cache_size(void)
return s->xbzrle_cache_size;
}
-/* migration thread support */
+/*
+ * Something bad happened to the RP stream, mark an error
+ * The caller shall print something to indicate why
+ */
+static void source_return_path_bad(MigrationState *s)
+{
+ s->rp_state.error = true;
+ migrate_fd_cleanup_src_rp(s);
+}
+/*
+ * Handles messages sent on the return path towards the source VM
+ *
+ */
+static void *source_return_path_thread(void *opaque)
+{
+ MigrationState *ms = opaque;
+ QEMUFile *rp = ms->return_path;
+ uint16_t expected_len, header_len, header_com;
+ const int max_len = 512;
+ uint8_t buf[max_len];
+ uint32_t tmp32;
+ int res;
+
+ DPRINTF("RP: %s entry", __func__);
+ while (rp && !qemu_file_get_error(rp) &&
+ migration_already_active(ms)) {
+ DPRINTF("RP: %s top of loop", __func__);
+ header_com = qemu_get_be16(rp);
+ header_len = qemu_get_be16(rp);
+
+ switch (header_com) {
+ case MIG_RPCOMM_SHUT:
+ case MIG_RPCOMM_ACK:
+ expected_len = 4;
+ break;
+
+ default:
+ error_report("RP: Received invalid cmd 0x%04x length 0x%04x",
+ header_com, header_len);
+ source_return_path_bad(ms);
+ goto out;
+ }
+
+ if (header_len > expected_len) {
+ error_report("RP: Received command 0x%04x with"
+ "incorrect length %d expecting %d",
+ header_com, header_len,
+ expected_len);
+ source_return_path_bad(ms);
+ goto out;
+ }
+
+ /* We know we've got a valid header by this point */
+ res = qemu_get_buffer(rp, buf, header_len);
+ if (res != header_len) {
+ DPRINTF("RP: Failed to read command data");
+ source_return_path_bad(ms);
+ goto out;
+ }
+
+ /* OK, we have the command and the data */
+ switch (header_com) {
+ case MIG_RPCOMM_SHUT:
+ tmp32 = be32_to_cpup((uint32_t *)buf);
+ if (tmp32) {
+ error_report("RP: Sibling indicated error %d", tmp32);
+ source_return_path_bad(ms);
+ } else {
+ DPRINTF("RP: SHUT received");
+ }
+ /*
+ * We'll let the main thread deal with closing the RP
+ * we could do a shutdown(2) on it, but we're the only user
+ * anyway, so there's nothing gained.
+ */
+ goto out;
+
+ case MIG_RPCOMM_ACK:
+ tmp32 = be32_to_cpup((uint32_t *)buf);
+ DPRINTF("RP: Received ACK 0x%x", tmp32);
+ atomic_xchg(&ms->rp_state.latest_ack, tmp32);
I didn't see *ms->rp_state.latest_ack* been used elsewhere, what's it used
for?;)
+ break;
+
+ default:
+ /* This shouldn't happen because we should catch this above */
+ DPRINTF("RP: Bad header_com in dispatch");
+ }
+ /* Latest command processed, now leave a gap for the next one */
+ header_com = MIG_RPCOMM_INVALID;
+ }
+ if (rp && qemu_file_get_error(rp)) {
+ DPRINTF("%s: rp bad at end", __func__);
+ source_return_path_bad(ms);
+ }
+
+ DPRINTF("%s: Bottom exit", __func__);
+
+out:
+ return NULL;
+}
+
+__attribute__ (( unused )) /* Until later in patch series */
+static int open_outgoing_return_path(MigrationState *ms)
+{
+
+ ms->return_path = qemu_file_get_return_path(ms->file);
+ if (!ms->return_path) {
+ return -1;
+ }
+
+ DPRINTF("%s: starting thread", __func__);
+ qemu_thread_create(&ms->rp_state.rp_thread, "return path",
+ source_return_path_thread, ms, QEMU_THREAD_JOINABLE);
+
+ DPRINTF("%s: continuing", __func__);
+
+ return 0;
+}
+
+__attribute__ (( unused )) /* Until later in patch series */
+static void await_outgoing_return_path_close(MigrationState *ms)
+{
+ /*
+ * If this is a normal exit then the destination will send a SHUT and the
+ * rp_thread will exit, however if there's an error we need to cause
+ * it to exit, which we can do by a shutdown.
+ * (canceling must also shutdown to stop us getting stuck here if
+ * the destination died at just the wrong place)
+ */
+ if (qemu_file_get_error(ms->file) && ms->return_path) {
+ qemu_file_shutdown(ms->return_path);
+ }
+ DPRINTF("%s: Joining", __func__);
+ qemu_thread_join(&ms->rp_state.rp_thread);
+ DPRINTF("%s: Exit", __func__);
+}
+
+/*
+ * Master migration thread on the source VM.
+ * It drives the migration and pumps the data down the outgoing channel.
+ */
static void *migration_thread(void *opaque)
{
MigrationState *s = opaque;
