From 9cd67421977a701272820987ff9e6f197b1b97b7 Mon Sep 17 00:00:00 2001 From: Cornelia Huck Date: Thu, 25 Dec 2008 13:39:06 +0100 Subject: [PATCH] [S390] cio: Fix reference counting for online/offline. The current code attempts to get an extra reference count for online devices by doing a get_device() in ccw_device_online() and a put_device() in ccw_device_done(). However, this - incorrectly obtains an extra reference for disconnected devices becoming available again (since they are already online) - needs special checks for css_init_done in order to handle the console device - is not obvious and - may incorretly drop a reference count in ccw_device_done() if that function is called after path verification for a device that just became not operational. So let's just get the reference in ccw_device_set_online() and drop it in ccw_device_set_offline(). (Unfortunately, we still need the special case in io_subchannel_probe().) Signed-off-by: Cornelia Huck Signed-off-by: Martin Schwidefsky --- drivers/s390/cio/device.c | 29 ++++++++++++++++++++++------- drivers/s390/cio/device_fsm.c | 5 ----- 2 files changed, 22 insertions(+), 12 deletions(-) diff --git a/drivers/s390/cio/device.c b/drivers/s390/cio/device.c index 647cbaca298e..039ef03cf217 100644 --- a/drivers/s390/cio/device.c +++ b/drivers/s390/cio/device.c @@ -376,19 +376,23 @@ int ccw_device_set_offline(struct ccw_device *cdev) dev_fsm_event(cdev, DEV_EVENT_NOTOPER); } spin_unlock_irq(cdev->ccwlock); + /* Give up reference from ccw_device_set_online(). */ + put_device(&cdev->dev); return ret; } spin_unlock_irq(cdev->ccwlock); - if (ret == 0) + if (ret == 0) { wait_event(cdev->private->wait_q, dev_fsm_final_state(cdev)); - else { + /* Give up reference from ccw_device_set_online(). */ + put_device(&cdev->dev); + } else { CIO_MSG_EVENT(0, "ccw_device_offline returned %d, " "device 0.%x.%04x\n", ret, cdev->private->dev_id.ssid, cdev->private->dev_id.devno); cdev->online = 1; } - return ret; + return ret; } /** @@ -411,6 +415,9 @@ int ccw_device_set_online(struct ccw_device *cdev) return -ENODEV; if (cdev->online || !cdev->drv) return -EINVAL; + /* Hold on to an extra reference while device is online. */ + if (!get_device(&cdev->dev)) + return -ENODEV; spin_lock_irq(cdev->ccwlock); ret = ccw_device_online(cdev); @@ -422,10 +429,15 @@ int ccw_device_set_online(struct ccw_device *cdev) "device 0.%x.%04x\n", ret, cdev->private->dev_id.ssid, cdev->private->dev_id.devno); + /* Give up online reference since onlining failed. */ + put_device(&cdev->dev); return ret; } - if (cdev->private->state != DEV_STATE_ONLINE) + if (cdev->private->state != DEV_STATE_ONLINE) { + /* Give up online reference since onlining failed. */ + put_device(&cdev->dev); return -ENODEV; + } if (!cdev->drv->set_online || cdev->drv->set_online(cdev) == 0) { cdev->online = 1; return 0; @@ -440,6 +452,8 @@ int ccw_device_set_online(struct ccw_device *cdev) "device 0.%x.%04x\n", ret, cdev->private->dev_id.ssid, cdev->private->dev_id.devno); + /* Give up online reference since onlining failed. */ + put_device(&cdev->dev); return (ret == 0) ? -ENODEV : ret; } @@ -1168,9 +1182,8 @@ static int io_subchannel_probe(struct subchannel *sch) ccw_device_register(cdev); /* * Check if the device is already online. If it is - * the reference count needs to be corrected - * (see ccw_device_online and css_init_done for the - * ugly details). + * the reference count needs to be corrected since we + * didn't obtain a reference in ccw_device_set_online. */ if (cdev->private->state != DEV_STATE_NOT_OPER && cdev->private->state != DEV_STATE_OFFLINE && @@ -1806,6 +1819,8 @@ ccw_device_remove (struct device *dev) "device 0.%x.%04x\n", ret, cdev->private->dev_id.ssid, cdev->private->dev_id.devno); + /* Give up reference obtained in ccw_device_set_online(). */ + put_device(&cdev->dev); } ccw_device_set_timeout(cdev, 0); cdev->drv = NULL; diff --git a/drivers/s390/cio/device_fsm.c b/drivers/s390/cio/device_fsm.c index 10bc03940fb3..01330cf5ae5e 100644 --- a/drivers/s390/cio/device_fsm.c +++ b/drivers/s390/cio/device_fsm.c @@ -399,9 +399,6 @@ ccw_device_done(struct ccw_device *cdev, int state) ccw_device_oper_notify(cdev); } wake_up(&cdev->private->wait_q); - - if (css_init_done && state != DEV_STATE_ONLINE) - put_device (&cdev->dev); } static int cmp_pgid(struct pgid *p1, struct pgid *p2) @@ -611,8 +608,6 @@ ccw_device_online(struct ccw_device *cdev) (cdev->private->state != DEV_STATE_BOXED)) return -EINVAL; sch = to_subchannel(cdev->dev.parent); - if (css_init_done && !get_device(&cdev->dev)) - return -ENODEV; ret = cio_enable_subchannel(sch, (u32)(addr_t)sch); if (ret != 0) { /* Couldn't enable the subchannel for i/o. Sick device. */ -- GitLab