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| author | Peter Oberparleiter <oberpar@linux.ibm.com> | 2024-04-10 12:46:19 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-04-27 18:07:09 +0300 |
| commit | 559f3a6333397ab6cd4a696edd65a70b6be62c6e (patch) | |
| tree | a3285b0a3ace7314d0818f03dedd9aaf00bae90e /drivers/s390 | |
| parent | beb3ff19a55d78d3c70f9284458c9d155818ae27 (diff) | |
| download | linux-559f3a6333397ab6cd4a696edd65a70b6be62c6e.tar.xz | |
s390/cio: fix race condition during online processing
[ Upstream commit 2d8527f2f911fab84aec04df4788c0c23af3df48 ]
A race condition exists in ccw_device_set_online() that can cause the
online process to fail, leaving the affected device in an inconsistent
state. As a result, subsequent attempts to set that device online fail
with return code ENODEV.
The problem occurs when a path verification request arrives after
a wait for final device state completed, but before the result state
is evaluated.
Fix this by ensuring that the CCW-device lock is held between
determining final state and checking result state.
Note that since:
commit 2297791c92d0 ("s390/cio: dont unregister subchannel from child-drivers")
path verification requests are much more likely to occur during boot,
resulting in an increased chance of this race condition occurring.
Fixes: 2297791c92d0 ("s390/cio: dont unregister subchannel from child-drivers")
Reviewed-by: Alexandra Winter <wintera@linux.ibm.com>
Reviewed-by: Vineeth Vijayan <vneethv@linux.ibm.com>
Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'drivers/s390')
| -rw-r--r-- | drivers/s390/cio/device.c | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/drivers/s390/cio/device.c b/drivers/s390/cio/device.c index 02813b63f90f..5666b9cc5d29 100644 --- a/drivers/s390/cio/device.c +++ b/drivers/s390/cio/device.c @@ -360,10 +360,8 @@ int ccw_device_set_online(struct ccw_device *cdev) spin_lock_irq(cdev->ccwlock); ret = ccw_device_online(cdev); - spin_unlock_irq(cdev->ccwlock); - if (ret == 0) - wait_event(cdev->private->wait_q, dev_fsm_final_state(cdev)); - else { + if (ret) { + spin_unlock_irq(cdev->ccwlock); CIO_MSG_EVENT(0, "ccw_device_online returned %d, " "device 0.%x.%04x\n", ret, cdev->private->dev_id.ssid, @@ -372,7 +370,12 @@ int ccw_device_set_online(struct ccw_device *cdev) put_device(&cdev->dev); return ret; } - spin_lock_irq(cdev->ccwlock); + /* Wait until a final state is reached */ + while (!dev_fsm_final_state(cdev)) { + spin_unlock_irq(cdev->ccwlock); + wait_event(cdev->private->wait_q, dev_fsm_final_state(cdev)); + spin_lock_irq(cdev->ccwlock); + } /* Check if online processing was successful */ if ((cdev->private->state != DEV_STATE_ONLINE) && (cdev->private->state != DEV_STATE_W4SENSE)) { |