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author | Stefan Weinhuber <wein@de.ibm.com> | 2011-04-20 10:15:30 +0200 |
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committer | Martin Schwidefsky <sky@mschwide.boeblingen.de.ibm.com> | 2011-04-20 10:15:43 +0200 |
commit | 65f8da475995f667af5298c644707dbd9d646ca6 (patch) | |
tree | bca8597443060e79f09a8843903bbc55b2dece52 /drivers/s390/block/dasd_int.h | |
parent | 2f666bcf757cb72549f360ef6da02f03620a48b6 (diff) | |
download | op-kernel-dev-65f8da475995f667af5298c644707dbd9d646ca6.zip op-kernel-dev-65f8da475995f667af5298c644707dbd9d646ca6.tar.gz |
[S390] dasd: fix race between open and offline
The dasd_open function uses the private_data pointer of the gendisk to
find the dasd_block structure that matches the gendisk. When a DASD
device is set offline, we set the private_data pointer of the gendisk
to NULL and later remove the dasd_block structure, but there is still
a small race window, in which dasd_open could first read a pointer
from the private_data field and then try to use it, after the structure
has already been freed.
To close this race window, we will store a pointer to the dasd_devmap
structure of the base device in the private_data field. The devmap
entries are not deleted, and we already have proper locking and
reference counting in place, so that we can safely get from a devmap
pointer to the dasd_device and dasd_block structures of the device.
Signed-off-by: Stefan Weinhuber <wein@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'drivers/s390/block/dasd_int.h')
-rw-r--r-- | drivers/s390/block/dasd_int.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/s390/block/dasd_int.h b/drivers/s390/block/dasd_int.h index df9f699..d1e4f2c 100644 --- a/drivers/s390/block/dasd_int.h +++ b/drivers/s390/block/dasd_int.h @@ -686,6 +686,9 @@ struct dasd_device *dasd_device_from_cdev(struct ccw_device *); struct dasd_device *dasd_device_from_cdev_locked(struct ccw_device *); struct dasd_device *dasd_device_from_devindex(int); +void dasd_add_link_to_gendisk(struct gendisk *, struct dasd_device *); +struct dasd_device *dasd_device_from_gendisk(struct gendisk *); + int dasd_parse(void); int dasd_busid_known(const char *); |