[kvm-unit-tests PATCH v4 4/8] migration: Support multiple migrations

[Nicholas Piggin <npiggin@gmail.com>]

Support multiple migrations by flipping dest file/socket variables to
source after the migration is complete, ready to start again. A new
destination is created if the test outputs the migrate line again.
Test cases may now switch to calling migrate() one or more times.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 lib/migrate.c         |  8 ++--
 lib/migrate.h         |  1 +
 scripts/arch-run.bash | 86 ++++++++++++++++++++++++++++++++++++-------
 3 files changed, 77 insertions(+), 18 deletions(-)

diff --git a/lib/migrate.c b/lib/migrate.c
index 527e63ae..b7721659 100644
--- a/lib/migrate.c
+++ b/lib/migrate.c
@@ -8,8 +8,10 @@
 #include <libcflat.h>
 #include "migrate.h"
 
-/* static for now since we only support migrating exactly once per test. */
-static void migrate(void)
+/*
+ * Initiate migration and wait for it to complete.
+ */
+void migrate(void)
 {
 	puts("Now migrate the VM, then press a key to continue...\n");
 	(void)getchar();
@@ -19,8 +21,6 @@ static void migrate(void)
 /*
  * Initiate migration and wait for it to complete.
  * If this function is called more than once, it is a no-op.
- * Since migrate_cmd can only migrate exactly once this function can
- * simplify the control flow, especially when skipping tests.
  */
 void migrate_once(void)
 {
diff --git a/lib/migrate.h b/lib/migrate.h
index 3c94e6af..2af06a72 100644
--- a/lib/migrate.h
+++ b/lib/migrate.h
@@ -6,4 +6,5 @@
  * Author: Nico Boehr <nrb@linux.ibm.com>
  */
 
+void migrate(void);
 void migrate_once(void);
diff --git a/scripts/arch-run.bash b/scripts/arch-run.bash
index 9a5aaddc..c2002d7a 100644
--- a/scripts/arch-run.bash
+++ b/scripts/arch-run.bash
@@ -129,12 +129,16 @@ run_migration ()
 		return 77
 	fi
 
+	migcmdline=$@
+
 	trap 'trap - TERM ; kill 0 ; exit 2' INT TERM
-	trap 'rm -f ${migout1} ${migout_fifo1} ${migsock} ${qmp1} ${qmp2} ${fifo}' RETURN EXIT
+	trap 'rm -f ${migout1} ${migout2} ${migout_fifo1} ${migout_fifo2} ${migsock} ${qmp1} ${qmp2} ${fifo}' RETURN EXIT
 
 	migsock=$(mktemp -u -t mig-helper-socket.XXXXXXXXXX)
 	migout1=$(mktemp -t mig-helper-stdout1.XXXXXXXXXX)
 	migout_fifo1=$(mktemp -u -t mig-helper-fifo-stdout1.XXXXXXXXXX)
+	migout2=$(mktemp -t mig-helper-stdout2.XXXXXXXXXX)
+	migout_fifo2=$(mktemp -u -t mig-helper-fifo-stdout2.XXXXXXXXXX)
 	qmp1=$(mktemp -u -t mig-helper-qmp1.XXXXXXXXXX)
 	qmp2=$(mktemp -u -t mig-helper-qmp2.XXXXXXXXXX)
 	fifo=$(mktemp -u -t mig-helper-fifo.XXXXXXXXXX)
@@ -142,20 +146,54 @@ run_migration ()
 	qmpout2=/dev/null
 
 	mkfifo ${migout_fifo1}
-	eval "$@" -chardev socket,id=mon1,path=${qmp1},server=on,wait=off \
+	mkfifo ${migout_fifo2}
+
+	eval "$migcmdline" \
+		-chardev socket,id=mon1,path=${qmp1},server=on,wait=off \
 		-mon chardev=mon1,mode=control > ${migout_fifo1} &
 	live_pid=$!
 	cat ${migout_fifo1} | tee ${migout1} &
 
-	# We have to use cat to open the named FIFO, because named FIFO's, unlike
-	# pipes, will block on open() until the other end is also opened, and that
-	# totally breaks QEMU...
+	# Start the first destination QEMU machine in advance of the test
+	# reaching the migration point, since we expect at least one migration.
+	# Then destination machines are started after the test outputs
+	# subsequent "Now migrate the VM" messages.
+	do_migration || return $?
+
+	while ps -p ${live_pid} > /dev/null ; do
+		# Wait for test exit or further migration messages.
+		if ! grep -q -i "Now migrate the VM" < ${migout1} ; then
+			sleep 0.1
+		else
+			do_migration || return $?
+		fi
+	done
+
+	wait ${live_pid}
+	ret=$?
+
+	while (( $(jobs -r | wc -l) > 0 )); do
+		sleep 0.1
+	done
+
+	return $ret
+}
+
+do_migration ()
+{
+	# We have to use cat to open the named FIFO, because named FIFO's,
+	# unlike pipes, will block on open() until the other end is also
+	# opened, and that totally breaks QEMU...
 	mkfifo ${fifo}
-	eval "$@" -chardev socket,id=mon2,path=${qmp2},server=on,wait=off \
-		-mon chardev=mon2,mode=control -incoming unix:${migsock} < <(cat ${fifo}) &
+	eval "$migcmdline" \
+		-chardev socket,id=mon2,path=${qmp2},server=on,wait=off \
+		-mon chardev=mon2,mode=control -incoming unix:${migsock} \
+		< <(cat ${fifo}) > ${migout_fifo2} &
 	incoming_pid=$!
+	cat ${migout_fifo2} | tee ${migout2} &
 
-	# The test must prompt the user to migrate, so wait for the "migrate" keyword
+	# The test must prompt the user to migrate, so wait for the
+	# "Now migrate VM" console message.
 	while ! grep -q -i "Now migrate the VM" < ${migout1} ; do
 		if ! ps -p ${live_pid} > /dev/null ; then
 			echo "ERROR: Test exit before migration point." >&2
@@ -164,7 +202,7 @@ run_migration ()
 			qmp ${qmp2} '"quit"'> ${qmpout2} 2>/dev/null
 			return 3
 		fi
-		sleep 1
+		sleep 0.1
 	done
 
 	# Wait until the destination has created the incoming and qmp sockets
@@ -176,7 +214,7 @@ run_migration ()
 	# Wait for the migration to complete
 	migstatus=`qmp ${qmp1} '"query-migrate"' | grep return`
 	while ! grep -q '"completed"' <<<"$migstatus" ; do
-		sleep 1
+		sleep 0.1
 		if ! migstatus=`qmp ${qmp1} '"query-migrate"'`; then
 			echo "ERROR: Querying migration state failed." >&2
 			echo > ${fifo}
@@ -192,14 +230,34 @@ run_migration ()
 			return 2
 		fi
 	done
+
 	qmp ${qmp1} '"quit"'> ${qmpout1} 2>/dev/null
+
+	# keypress to dst so getchar completes and test continues
 	echo > ${fifo}
-	wait $incoming_pid
+	rm ${fifo}
+
+	# Ensure the incoming socket is removed, ready for next destination
+	if [ -S ${migsock} ] ; then
+		echo "ERROR: Incoming migration socket not removed after migration." >& 2
+		qmp ${qmp2} '"quit"'> ${qmpout2} 2>/dev/null
+		return 2
+	fi
+
+	wait ${live_pid}
 	ret=$?
 
-	while (( $(jobs -r | wc -l) > 0 )); do
-		sleep 0.5
-	done
+	# Now flip the variables because dest becomes source
+	live_pid=${incoming_pid}
+	tmp=${migout1}
+	migout1=${migout2}
+	migout2=${tmp}
+	tmp=${migout_fifo1}
+	migout_fifo1=${migout_fifo2}
+	migout_fifo2=${tmp}
+	tmp=${qmp1}
+	qmp1=${qmp2}
+	qmp2=${tmp}
 
 	return $ret
 }
-- 
2.42.0