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[SRU,Cosmic,Bionic,Xenial,0/1] Fixes for LP1801686

Message ID CA+jPhpdjaPehvf3XXOyOTLGnw=sguGPcTBKvhKqrYZCL=7bvuA@mail.gmail.com
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Series Fixes for LP1801686 | expand

Message

Frank Heimes Nov. 5, 2018, 6:21 p.m. UTC 
BugLink: http://bugs.launchpad.net/bugs/1801686

== SRU Justification ==

Description: qdio: reset old sbal_state flags

Symptom:
   af_iucv socket using HiperSockets may stall.
Problem:
   When allocating a new AOB fails, handle_outbound() is
still capable of transmitting the selected buffer
(just without async completion).
But if a previous transfer on this queue slot used
async completion, its sbal_state flags field is still set
to QDIO_OUTBUF_STATE_FLAG_PENDING.
So when the upper layer driver sees this stale flag, it
expects an async completion that never happens.
Solution:
   Unconditionally clear the buffer's flags field.

== Fix ==

64e03ff72623b8c2ea89ca3cb660094e019ed4ae ("s390/qdio: reset old sbal_state
flags")

== Regression Potential ==

Low, because:
- s390x only
- further limited to qeth driver (OSA Express networking)
- changes are limited to two files and 6 lines
   - arch/s390/include/asm/qdio.h b/arch/s390/include/asm/qdio.h
   - drivers/s390/cio/qdio_main.c b/drivers/s390/cio/qdio_main.c
- error was identified at IBM/customer, fix was created there and tested
upfront
- (changes are upstream in 4.20 (according to bug description,
   but in 4.19 according to 'git tag'),
   hence will make it automatically into 'disco')

== Test Case ==

Test case / reproduction:
Error inject and then simulate out-of-memory situation.

Comments

Frank Heimes Nov. 6, 2018, 3:21 p.m. UTC | #1 
NAK because the PATCH subject only mentioned bionic - cosmic and xenial (as
stated in the main SRU mail) were missing on the patch.

resubmitting with corrections as v2