[PATCH 3/7] md: test for MD_RECOVERY_DONE in stop_sync_thread

[Mikulas Patocka]

stop_sync_thread sets MD_RECOVERY_INTR and then waits for
MD_RECOVERY_RUNNING to be cleared. However, md_do_sync will not clear
MD_RECOVERY_RUNNING when exiting, it will set MD_RECOVERY_DONE instead.

So, we must wait for MD_RECOVERY_DONE to be set as well.

This patch fixes a deadlock in the LVM2 test shell/integrity-caching.sh.

sysrq: Show Blocked State
task:lvm             state:D stack:0     pid:11422  tgid:11422 ppid:1374   
flags:0x00004002
Call Trace:
 <TASK>
 __schedule+0x228/0x570
 schedule+0x29/0xa0
 schedule_timeout+0x6a/0xd0
 ? timer_shutdown_sync+0x10/0x10
 stop_sync_thread+0x141/0x180 [md_mod]
 ? housekeeping_test_cpu+0x30/0x30
 __md_stop_writes+0x10/0xd0 [md_mod]
 md_stop+0x9/0x20 [md_mod]
 raid_dtr+0x1e/0x60 [dm_raid]
 dm_table_destroy+0x53/0x110 [dm_mod]
 __dm_destroy+0x10b/0x1e0 [dm_mod]
 ? table_clear+0xa0/0xa0 [dm_mod]
 dev_remove+0xd4/0x110 [dm_mod]
 ctl_ioctl+0x2e1/0x570 [dm_mod]
 dm_ctl_ioctl+0x5/0x10 [dm_mod]
 __x64_sys_ioctl+0x85/0xa0
 do_syscall_64+0x5d/0x1a0
 entry_SYSCALL_64_after_hwframe+0x46/0x4e

Signed-off-by: Mikulas Patocka <mpato...@redhat.com>
Cc: sta...@vger.kernel.org      # v6.7
Fixes: 130443d60b1b ("md: refactor idle/frozen_sync_thread() to fix deadlock")

---
 drivers/md/md.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

Index: linux-2.6/drivers/md/md.c
===================================================================
--- linux-2.6.orig/drivers/md/md.c
+++ linux-2.6/drivers/md/md.c
@@ -4881,7 +4881,8 @@ static void stop_sync_thread(struct mdde
        if (check_seq)
                sync_seq = atomic_read(&mddev->sync_seq);
 
-       if (!test_bit(MD_RECOVERY_RUNNING, &mddev->recovery)) {
+       if (!test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
+           test_bit(MD_RECOVERY_DONE, &mddev->recovery)) {
                if (!locked)
                        mddev_unlock(mddev);
                return;
@@ -4901,6 +4902,7 @@ retry:
 
        if (!wait_event_timeout(resync_wait,
                   !test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
+                  test_bit(MD_RECOVERY_DONE, &mddev->recovery) ||
                   (check_seq && sync_seq != atomic_read(&mddev->sync_seq)),
                   HZ / 10))
                goto retry;