From 91c36919a456589f4f073671474a1f899e0d3c2b Mon Sep 17 00:00:00 2001 From: Peter Oberparleiter Date: Thu, 21 Aug 2008 19:46:39 +0200 Subject: [PATCH] [S390] cio: call ccw driver notify function with lock held Calling a ccw driver's notify function without the ccw device lock held opens up a race window between discovery and handling of a change in the device operational state. As a result, the device driver may encounter unexpected device malfunction, leading to out-of-retry situations or similar. Remove race by extending the ccw device lock from state change discovery to the calling of the notify function. Signed-off-by: Peter Oberparleiter Signed-off-by: Martin Schwidefsky --- drivers/s390/block/dasd.c | 5 +---- drivers/s390/cio/css.c | 1 - drivers/s390/cio/device.c | 40 +++++++++++++++++------------------ drivers/s390/cio/device.h | 2 +- drivers/s390/cio/device_fsm.c | 31 ++++++++++++++++----------- 5 files changed, 41 insertions(+), 38 deletions(-) diff --git a/drivers/s390/block/dasd.c b/drivers/s390/block/dasd.c index 1b6c52ef73..acb78017e7 100644 --- a/drivers/s390/block/dasd.c +++ b/drivers/s390/block/dasd.c @@ -2333,13 +2333,11 @@ int dasd_generic_notify(struct ccw_device *cdev, int event) { struct dasd_device *device; struct dasd_ccw_req *cqr; - unsigned long flags; int ret; - device = dasd_device_from_cdev(cdev); + device = dasd_device_from_cdev_locked(cdev); if (IS_ERR(device)) return 0; - spin_lock_irqsave(get_ccwdev_lock(cdev), flags); ret = 0; switch (event) { case CIO_GONE: @@ -2369,7 +2367,6 @@ int dasd_generic_notify(struct ccw_device *cdev, int event) ret = 1; break; } - spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags); dasd_put_device(device); return ret; } diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c index 46c021d880..51489eff6b 100644 --- a/drivers/s390/cio/css.c +++ b/drivers/s390/cio/css.c @@ -477,7 +477,6 @@ void css_schedule_eval_all(void) void css_wait_for_slow_path(void) { - flush_workqueue(ccw_device_notify_work); flush_workqueue(slow_path_wq); } diff --git a/drivers/s390/cio/device.c b/drivers/s390/cio/device.c index e818d0c54c..28221030b8 100644 --- a/drivers/s390/cio/device.c +++ b/drivers/s390/cio/device.c @@ -150,7 +150,6 @@ static struct css_driver io_subchannel_driver = { }; struct workqueue_struct *ccw_device_work; -struct workqueue_struct *ccw_device_notify_work; wait_queue_head_t ccw_device_init_wq; atomic_t ccw_device_init_count; @@ -168,11 +167,6 @@ init_ccw_bus_type (void) ccw_device_work = create_singlethread_workqueue("cio"); if (!ccw_device_work) return -ENOMEM; /* FIXME: better errno ? */ - ccw_device_notify_work = create_singlethread_workqueue("cio_notify"); - if (!ccw_device_notify_work) { - ret = -ENOMEM; /* FIXME: better errno ? */ - goto out_err; - } slow_path_wq = create_singlethread_workqueue("kslowcrw"); if (!slow_path_wq) { ret = -ENOMEM; /* FIXME: better errno ? */ @@ -192,8 +186,6 @@ init_ccw_bus_type (void) out_err: if (ccw_device_work) destroy_workqueue(ccw_device_work); - if (ccw_device_notify_work) - destroy_workqueue(ccw_device_notify_work); if (slow_path_wq) destroy_workqueue(slow_path_wq); return ret; @@ -204,7 +196,6 @@ cleanup_ccw_bus_type (void) { css_driver_unregister(&io_subchannel_driver); bus_unregister(&ccw_bus_type); - destroy_workqueue(ccw_device_notify_work); destroy_workqueue(ccw_device_work); } @@ -1496,11 +1487,22 @@ static void device_set_disconnected(struct ccw_device *cdev) ccw_device_schedule_recovery(); } +void ccw_device_set_notoper(struct ccw_device *cdev) +{ + struct subchannel *sch = to_subchannel(cdev->dev.parent); + + CIO_TRACE_EVENT(2, "notoper"); + CIO_TRACE_EVENT(2, sch->dev.bus_id); + ccw_device_set_timeout(cdev, 0); + cio_disable_subchannel(sch); + cdev->private->state = DEV_STATE_NOT_OPER; +} + static int io_subchannel_sch_event(struct subchannel *sch, int slow) { int event, ret, disc; unsigned long flags; - enum { NONE, UNREGISTER, UNREGISTER_PROBE, REPROBE } action; + enum { NONE, UNREGISTER, UNREGISTER_PROBE, REPROBE, DISC } action; struct ccw_device *cdev; spin_lock_irqsave(sch->lock, flags); @@ -1535,16 +1537,11 @@ static int io_subchannel_sch_event(struct subchannel *sch, int slow) } /* fall through */ case CIO_GONE: - /* Prevent unwanted effects when opening lock. */ - cio_disable_subchannel(sch); - device_set_disconnected(cdev); /* Ask driver what to do with device. */ - action = UNREGISTER; - spin_unlock_irqrestore(sch->lock, flags); - ret = io_subchannel_notify(sch, event); - spin_lock_irqsave(sch->lock, flags); - if (ret) - action = NONE; + if (io_subchannel_notify(sch, event)) + action = DISC; + else + action = UNREGISTER; break; case CIO_REVALIDATE: /* Device will be removed, so no notify necessary. */ @@ -1565,6 +1562,7 @@ static int io_subchannel_sch_event(struct subchannel *sch, int slow) switch (action) { case UNREGISTER: case UNREGISTER_PROBE: + ccw_device_set_notoper(cdev); /* Unregister device (will use subchannel lock). */ spin_unlock_irqrestore(sch->lock, flags); css_sch_device_unregister(sch); @@ -1577,6 +1575,9 @@ static int io_subchannel_sch_event(struct subchannel *sch, int slow) case REPROBE: ccw_device_trigger_reprobe(cdev); break; + case DISC: + device_set_disconnected(cdev); + break; default: break; } @@ -1828,5 +1829,4 @@ EXPORT_SYMBOL(ccw_driver_unregister); EXPORT_SYMBOL(get_ccwdev_by_busid); EXPORT_SYMBOL(ccw_bus_type); EXPORT_SYMBOL(ccw_device_work); -EXPORT_SYMBOL(ccw_device_notify_work); EXPORT_SYMBOL_GPL(ccw_device_get_subchannel_id); diff --git a/drivers/s390/cio/device.h b/drivers/s390/cio/device.h index 9800a8335a..6f5c3f2b35 100644 --- a/drivers/s390/cio/device.h +++ b/drivers/s390/cio/device.h @@ -72,7 +72,6 @@ dev_fsm_final_state(struct ccw_device *cdev) } extern struct workqueue_struct *ccw_device_work; -extern struct workqueue_struct *ccw_device_notify_work; extern wait_queue_head_t ccw_device_init_wq; extern atomic_t ccw_device_init_count; @@ -120,6 +119,7 @@ int ccw_device_stlck(struct ccw_device *); void ccw_device_trigger_reprobe(struct ccw_device *); void ccw_device_kill_io(struct ccw_device *); int ccw_device_notify(struct ccw_device *, int); +void ccw_device_set_notoper(struct ccw_device *cdev); /* qdio needs this. */ void ccw_device_set_timeout(struct ccw_device *, int); diff --git a/drivers/s390/cio/device_fsm.c b/drivers/s390/cio/device_fsm.c index 8b5fe57fb2..550508df95 100644 --- a/drivers/s390/cio/device_fsm.c +++ b/drivers/s390/cio/device_fsm.c @@ -337,26 +337,34 @@ int ccw_device_notify(struct ccw_device *cdev, int event) return 0; if (!cdev->online) return 0; + CIO_MSG_EVENT(2, "notify called for 0.%x.%04x, event=%d\n", + cdev->private->dev_id.ssid, cdev->private->dev_id.devno, + event); return cdev->drv->notify ? cdev->drv->notify(cdev, event) : 0; } -static void -ccw_device_oper_notify(struct work_struct *work) +static void cmf_reenable_delayed(struct work_struct *work) { struct ccw_device_private *priv; struct ccw_device *cdev; - int ret; priv = container_of(work, struct ccw_device_private, kick_work); cdev = priv->cdev; - ret = ccw_device_notify(cdev, CIO_OPER); - if (ret) { + cmf_reenable(cdev); +} + +static void ccw_device_oper_notify(struct ccw_device *cdev) +{ + if (ccw_device_notify(cdev, CIO_OPER)) { /* Reenable channel measurements, if needed. */ - cmf_reenable(cdev); - wake_up(&cdev->private->wait_q); - } else - /* Driver doesn't want device back. */ - ccw_device_do_unreg_rereg(work); + PREPARE_WORK(&cdev->private->kick_work, cmf_reenable_delayed); + queue_work(ccw_device_work, &cdev->private->kick_work); + return; + } + /* Driver doesn't want device back. */ + ccw_device_set_notoper(cdev); + PREPARE_WORK(&cdev->private->kick_work, ccw_device_do_unreg_rereg); + queue_work(ccw_device_work, &cdev->private->kick_work); } /* @@ -386,8 +394,7 @@ ccw_device_done(struct ccw_device *cdev, int state) if (cdev->private->flags.donotify) { cdev->private->flags.donotify = 0; - PREPARE_WORK(&cdev->private->kick_work, ccw_device_oper_notify); - queue_work(ccw_device_notify_work, &cdev->private->kick_work); + ccw_device_oper_notify(cdev); } wake_up(&cdev->private->wait_q); -- 2.39.5