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author | Vineeth Vijayan <vneethv@linux.ibm.com> | 2022-11-11 15:46:33 +0300 |
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committer | Heiko Carstens <hca@linux.ibm.com> | 2023-01-31 20:56:36 +0300 |
commit | 0c6924c262e819c4997b9cae0df6bd6e7b0b8754 (patch) | |
tree | 4dc69f4bdc69cb7909c41f2205072fb426bd8b19 /arch/s390/include/asm/ccwdev.h | |
parent | 05178996e1a77e2a4664536e6d101a086a905034 (diff) | |
download | linux-0c6924c262e819c4997b9cae0df6bd6e7b0b8754.tar.xz |
s390/cio: introduce locking for register/unregister functions
Unbinding an I/O subchannel with a child-CCW device in disconnected
state sometimes causes a kernel-panic. The race condition was seen
mostly during testing, when setting all the CHPIDs of a device to
offline and at the same time, the unbinding the I/O subchannel driver.
The kernel-panic occurs because of double delete, the I/O subchannel
driver calls device_del on the CCW device while another device_del
invocation for the same device is in-flight. For instance, disabling
all the CHPIDs will trigger the ccw_device_remove function, which will
call a ccw_device_unregister(), which ends up calling the device_del()
which is asynchronous via cdev's todo workqueue. And unbinding the I/O
subchannel driver calls io_subchannel_remove() function which calls the
ccw_device_unregister() and device_del().
This double delete can be prevented by serializing all CCW device
registration/unregistration calls into the driver core. This patch
introduces a mutex which will be used for this purpose.
Signed-off-by: Vineeth Vijayan <vneethv@linux.ibm.com>
Reported-by: Boris Fiuczynski <fiuczy@linux.ibm.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Diffstat (limited to 'arch/s390/include/asm/ccwdev.h')
-rw-r--r-- | arch/s390/include/asm/ccwdev.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/s390/include/asm/ccwdev.h b/arch/s390/include/asm/ccwdev.h index bd1596810cc1..91d261751d25 100644 --- a/arch/s390/include/asm/ccwdev.h +++ b/arch/s390/include/asm/ccwdev.h @@ -15,6 +15,7 @@ #include <asm/fcx.h> #include <asm/irq.h> #include <asm/schid.h> +#include <linux/mutex.h> /* structs from asm/cio.h */ struct irb; @@ -87,6 +88,7 @@ struct ccw_device { spinlock_t *ccwlock; /* private: */ struct ccw_device_private *private; /* cio private information */ + struct mutex reg_mutex; /* public: */ struct ccw_device_id id; struct ccw_driver *drv; |