From: Yu Kuai <yukuai3@xxxxxxxxxx>
Currently, for idle and frozen, action_store will hold 'reconfig_mutex'
and call md_reap_sync_thread() to stop sync thread, however, this will
cause deadlock (explained in the next patch). In order to fix the
problem, following patch will release 'reconfig_mutex' and wait on
'resync_wait', like md_set_readonly() and do_md_stop() does.
Consider that action_store() will set/clear 'MD_RECOVERY_FROZEN'
unconditionally, which might cause unexpected problems, for example,
frozen just set 'MD_RECOVERY_FROZEN' and is still in progress, while
'idle' clear 'MD_RECOVERY_FROZEN' and new sync thread is started, which
might starve in progress frozen.
This patch add a mutex to synchronize idle and frozen from
action_store().
Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
---
drivers/md/md.c | 5 +++++
drivers/md/md.h | 3 +++
2 files changed, 8 insertions(+)
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 076936fee65a..223c03149852 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -656,6 +656,7 @@ void mddev_init(struct mddev *mddev)
mutex_init(&mddev->open_mutex);
mutex_init(&mddev->reconfig_mutex);
mutex_init(&mddev->bitmap_info.mutex);
+ mutex_init(&mddev->sync_mutex);
INIT_LIST_HEAD(&mddev->disks);
INIT_LIST_HEAD(&mddev->all_mddevs);
timer_setup(&mddev->safemode_timer, md_safemode_timeout, 0);
@@ -4783,14 +4784,18 @@ static void stop_sync_thread(struct mddev *mddev)
static void idle_sync_thread(struct mddev *mddev)
{
+ mutex_lock(&mddev->sync_mutex);
clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
stop_sync_thread(mddev);
+ mutex_unlock(&mddev->sync_mutex);
}
static void frozen_sync_thread(struct mddev *mddev)
{
+ mutex_lock(&mddev->sync_mutex);
set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
stop_sync_thread(mddev);
+ mutex_unlock(&mddev->sync_mutex);
}
static ssize_t
diff --git a/drivers/md/md.h b/drivers/md/md.h
index e148e3c83b0d..64474e458545 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -534,6 +534,9 @@ struct mddev {
bool has_superblocks:1;
bool fail_last_dev:1;
bool serialize_policy:1;
+
+ /* Used to synchronize idle and frozen for action_store() */
+ struct mutex sync_mutex;
};
enum recovery_flags {
--
2.31.1
