3.16.78-rc1 review patch. If anyone has any objections, please let me know.
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From: Stefan Haberland sth@linux.ibm.com
commit 41995342b40c418a47603e1321256d2c4a2ed0fb upstream.
After getting a storage server event that causes the DASD device driver to update its unit address configuration during a device shutdown there is the possibility of an endless loop in the device driver.
In the system log there will be ongoing DASD error messages with RC: -19.
The reason is that the loop starting the ruac request only terminates when the retry counter is decreased to 0. But in the sleep_on function there are early exit paths that do not decrease the retry counter.
Prevent an endless loop by handling those cases separately.
Remove the unnecessary do..while loop since the sleep_on function takes care of retries by itself.
Fixes: 8e09f21574ea ("[S390] dasd: add hyper PAV support to DASD device driver, part 1") Signed-off-by: Stefan Haberland sth@linux.ibm.com Reviewed-by: Jan Hoeppner hoeppner@linux.ibm.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/s390/block/dasd_alias.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-)
--- a/drivers/s390/block/dasd_alias.c +++ b/drivers/s390/block/dasd_alias.c @@ -396,6 +396,20 @@ suborder_not_supported(struct dasd_ccw_r char msg_format; char msg_no;
+ /* + * intrc values ENODEV, ENOLINK and EPERM + * will be optained from sleep_on to indicate that no + * IO operation can be started + */ + if (cqr->intrc == -ENODEV) + return 1; + + if (cqr->intrc == -ENOLINK) + return 1; + + if (cqr->intrc == -EPERM) + return 1; + sense = dasd_get_sense(&cqr->irb); if (!sense) return 0; @@ -460,12 +474,8 @@ static int read_unit_address_configurati lcu->flags &= ~NEED_UAC_UPDATE; spin_unlock_irqrestore(&lcu->lock, flags);
- do { - rc = dasd_sleep_on(cqr); - if (rc && suborder_not_supported(cqr)) - return -EOPNOTSUPP; - } while (rc && (cqr->retries > 0)); - if (rc) { + rc = dasd_sleep_on(cqr); + if (rc && !suborder_not_supported(cqr)) { spin_lock_irqsave(&lcu->lock, flags); lcu->flags |= NEED_UAC_UPDATE; spin_unlock_irqrestore(&lcu->lock, flags);