Merge remote-tracking branch 'remotes/stefanha/tags/block-pull-reques…

…t' into staging

Pull request

Changelog: No user-visible changes.

# gpg: Signature made Thu 24 Jan 2019 10:28:53 GMT
# gpg:                using RSA key 9CA4ABB381AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>"
# gpg:                 aka "Stefan Hajnoczi <stefanha@gmail.com>"
# Primary key fingerprint: 8695 A8BF D3F9 7CDA AC35  775A 9CA4 ABB3 81AB 73C8

* remotes/stefanha/tags/block-pull-request:
  qemu-coroutine-sleep: drop CoSleepCB
  iotests: add 238 for throttling tgm unregister iothread segfault
  throttle-groups: fix restart coroutine iothread race

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

block/throttle-groups.c

@@ -415,6 +415,9 @@ static void coroutine_fn throttle_group_restart_queue_entry(void *opaque)
     }
 
     g_free(data);
+
+    atomic_dec(&tgm->restart_pending);
+    aio_wait_kick();
 }
 
 static void throttle_group_restart_queue(ThrottleGroupMember *tgm, bool is_write)
@@ -430,6 +433,8 @@ static void throttle_group_restart_queue(ThrottleGroupMember *tgm, bool is_write
      * be no timer pending on this tgm at this point */
     assert(!timer_pending(tgm->throttle_timers.timers[is_write]));
 
+    atomic_inc(&tgm->restart_pending);
+
     co = qemu_coroutine_create(throttle_group_restart_queue_entry, rd);
     aio_co_enter(tgm->aio_context, co);
 }
@@ -538,6 +543,7 @@ void throttle_group_register_tgm(ThrottleGroupMember *tgm,
 
     tgm->throttle_state = ts;
     tgm->aio_context = ctx;
+    atomic_set(&tgm->restart_pending, 0);
 
     qemu_mutex_lock(&tg->lock);
     /* If the ThrottleGroup is new set this ThrottleGroupMember as the token */
@@ -584,6 +590,9 @@ void throttle_group_unregister_tgm(ThrottleGroupMember *tgm)
         return;
     }
 
+    /* Wait for throttle_group_restart_queue_entry() coroutines to finish */
+    AIO_WAIT_WHILE(tgm->aio_context, atomic_read(&tgm->restart_pending) > 0);
+
     qemu_mutex_lock(&tg->lock);
     for (i = 0; i < 2; i++) {
         assert(tgm->pending_reqs[i] == 0);

include/block/throttle-groups.h

@@ -43,6 +43,11 @@ typedef struct ThrottleGroupMember {
      */
     unsigned int io_limits_disabled;
 
+    /* Number of pending throttle_group_restart_queue_entry() coroutines.
+     * Accessed with atomic operations.
+     */
+    unsigned int restart_pending;
+
     /* The following fields are protected by the ThrottleGroup lock.
      * See the ThrottleGroup documentation for details.
      * throttle_state tells us if I/O limits are configured. */

tests/qemu-iotests/238

@@ -0,0 +1,47 @@
+#!/usr/bin/env python
+#
+# Regression test for throttle group member unregister segfault with iothread
+#
+# Copyright (c) 2019 Red Hat, Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+import sys
+import os
+import iotests
+from iotests import log
+
+sys.path.append(os.path.join(os.path.dirname(__file__), '..', '..', 'scripts'))
+
+from qemu import QEMUMachine
+
+if iotests.qemu_default_machine == 's390-ccw-virtio':
+    virtio_scsi_device = 'virtio-scsi-ccw'
+else:
+    virtio_scsi_device = 'virtio-scsi-pci'
+
+vm = QEMUMachine(iotests.qemu_prog)
+vm.add_args('-machine', 'accel=kvm')
+vm.launch()
+
+log(vm.qmp('blockdev-add', node_name='hd0', driver='null-co'))
+log(vm.qmp('object-add', qom_type='iothread', id='iothread0'))
+log(vm.qmp('device_add', id='scsi0', driver=virtio_scsi_device, iothread='iothread0'))
+log(vm.qmp('device_add', id='scsi-hd0', driver='scsi-hd', drive='hd0'))
+log(vm.qmp('block_set_io_throttle', id='scsi-hd0', bps=0, bps_rd=0, bps_wr=0,
+           iops=1000, iops_rd=0, iops_wr=0, conv_keys=False))
+log(vm.qmp('device_del', id='scsi-hd0'))
+
+vm.shutdown()

tests/qemu-iotests/238.out

@@ -0,0 +1,6 @@
+{"return": {}}
+{"return": {}}
+{"return": {}}
+{"return": {}}
+{"return": {}}
+{"return": {}}

tests/qemu-iotests/group

@@ -234,3 +234,4 @@
 234 auto quick migration
 235 auto quick
 236 auto quick
+238 auto quick

util/qemu-coroutine-sleep.c

@@ -17,38 +17,31 @@
 #include "qemu/timer.h"
 #include "block/aio.h"
 
-typedef struct CoSleepCB {
-    QEMUTimer *ts;
-    Coroutine *co;
-} CoSleepCB;
-
 static void co_sleep_cb(void *opaque)
 {
-    CoSleepCB *sleep_cb = opaque;
+    Coroutine *co = opaque;
 
     /* Write of schedule protected by barrier write in aio_co_schedule */
-    atomic_set(&sleep_cb->co->scheduled, NULL);
-    aio_co_wake(sleep_cb->co);
+    atomic_set(&co->scheduled, NULL);
+    aio_co_wake(co);
 }
 
 void coroutine_fn qemu_co_sleep_ns(QEMUClockType type, int64_t ns)
 {
     AioContext *ctx = qemu_get_current_aio_context();
-    CoSleepCB sleep_cb = {
-        .co = qemu_coroutine_self(),
-    };
+    QEMUTimer *ts;
+    Coroutine *co = qemu_coroutine_self();
 
-    const char *scheduled = atomic_cmpxchg(&sleep_cb.co->scheduled, NULL,
-                                           __func__);
+    const char *scheduled = atomic_cmpxchg(&co->scheduled, NULL, __func__);
     if (scheduled) {
         fprintf(stderr,
                 "%s: Co-routine was already scheduled in '%s'\n",
                 __func__, scheduled);
         abort();
     }
-    sleep_cb.ts = aio_timer_new(ctx, type, SCALE_NS, co_sleep_cb, &sleep_cb);
-    timer_mod(sleep_cb.ts, qemu_clock_get_ns(type) + ns);
+    ts = aio_timer_new(ctx, type, SCALE_NS, co_sleep_cb, co);
+    timer_mod(ts, qemu_clock_get_ns(type) + ns);
     qemu_coroutine_yield();
-    timer_del(sleep_cb.ts);
-    timer_free(sleep_cb.ts);
+    timer_del(ts);
+    timer_free(ts);
 }