This is patch to fix the race occurs between bus detach and alua_rtpg. It fluses the all pending workqueue in bus detach handler, so it can avoid race between alua_bus_detach and alua_rtpg. Here is call trace where race got detected. multipathd call stack: [exception RIP: native_queued_spin_lock_slowpath+100] --- <NMI exception stack> --- native_queued_spin_lock_slowpath at ffffffff89307f54 queued_spin_lock_slowpath at ffffffff89307c18 _raw_spin_lock_irq at ffffffff89bd797b alua_bus_detach at ffffffff8984dcc8 scsi_dh_release_device at ffffffff8984b6f2 scsi_device_dev_release_usercontext at ffffffff89846edf execute_in_process_context at ffffffff892c3e60 scsi_device_dev_release at ffffffff8984637c device_release at ffffffff89800fbc kobject_cleanup at ffffffff89bb1196 kobject_put at ffffffff89bb12ea put_device at ffffffff89801283 scsi_device_put at ffffffff89838d5b scsi_disk_put at ffffffffc051f650 [sd_mod] sd_release at ffffffffc051f8a2 [sd_mod] __blkdev_put at ffffffff8952c79e blkdev_put at ffffffff8952c80c blkdev_close at ffffffff8952c8b5 __fput at ffffffff894e55e6 ____fput at ffffffff894e57ee task_work_run at ffffffff892c94dc exit_to_usermode_loop at ffffffff89204b12 do_syscall_64 at ffffffff892044da entry_SYSCALL_64_after_hwframe at ffffffff89c001b8 kworker: [exception RIP: alua_rtpg+2003] account_entity_dequeue at ffffffff892e42c1 alua_rtpg_work at ffffffff8984f097 process_one_work at ffffffff892c4c29 worker_thread at ffffffff892c5a4f kthread at ffffffff892cb135 ret_from_fork at ffffffff89c00354 Signed-off-by: Jitendra Khasdev <jitendra.khasdev@xxxxxxxxxx> --- drivers/scsi/device_handler/scsi_dh_alua.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c index f32da0c..024a752 100644 --- a/drivers/scsi/device_handler/scsi_dh_alua.c +++ b/drivers/scsi/device_handler/scsi_dh_alua.c @@ -1144,6 +1144,9 @@ static void alua_bus_detach(struct scsi_device *sdev) struct alua_dh_data *h = sdev->handler_data; struct alua_port_group *pg; + sdev_printk(KERN_INFO, sdev, "%s: flushing workqueues\n", ALUA_DH_NAME); + flush_workqueue(kaluad_wq); + spin_lock(&h->pg_lock); pg = rcu_dereference_protected(h->pg, lockdep_is_held(&h->pg_lock)); rcu_assign_pointer(h->pg, NULL); -- 1.8.3.1
