scsi: libsas: Support SATA PHY connection rate unmatch fixing during discovery

[dann frazier]

[Impact]
SATA disks may be unusable
will not be usable when:
 - The disk is connected through a SAS expander
 - Controller uses a libsas-based driver (mvsas, aic94xx, hisi_sas)
 - link rate between expander & disk is greater than link between controller and expander

This is unlikely to occur in any production environment, but has occurred in early silicon testing. Fixing this would be helpful in those environments.

[Test Case]
See conditions in "Impact"

Can be simulated with:
for f in /sys/class/sas_phy/phy-1\:*/maximum_linkrate; do
  echo "3.0 Gbit" | sudo tee $f
done

[Fix]
cec9771d2e954 scsi: libsas: Support SATA PHY connection rate unmatch fixing during discovery

[Regression Risk]
Impact is restricted to drivers that use libsas: mvsas, aic94xx & hisi_sas.
Code change is all within an "if" statement that meets these restrictions.
A bug in this code could possibly reduce the speed of an otherwise working disk connection.

[dann frazier (dannf)]

This change should qualify for an SRU. However, Canonical does not have the described hardware. We will need help from Huawei to test the SRU. Can Huawei commit to the following steps?

 1) Test a PPA build with this fix (both 4.15 and 4.18) by 2019-03-27. Canonical can prepare this PPA.
 2) After official Ubuntu kernel build, re-test both kernels to verify the fix. During the week of 2019-04-08.

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux - 5.0.0-11.12

---------------
linux (5.0.0-11.12) disco; urgency=medium

  * linux: 5.0.0-11.12 -proposed tracker (LP: #1824383)

  * hns3: PPU_PF_ABNORMAL_INT_ST over_8bd_no_fe found [error status=0x1]
    (LP: #1824194)
    - net: hns3: fix for not calculating tx bd num correctly

  * disco: unable to use iptables/enable ufw under -virtual kernel
    (LP: #1823862)
    - [Packaging] add bpfilter to linux-modules

  * Make shiftfs a module rather than built-in (LP: #1824354)
    - [Config] CONFIG_SHIFT_FS=m

  * shiftfs: chown sets untranslated ids in lower fs (LP: #1824350)
    - SAUCE: shiftfs: use translated ids when chaning lower fs attrs

  * [Hyper-V] KVP daemon fails to start on first boot of disco VM (LP: #1820063)
    - [Packaging] bind hv_kvp_daemon startup to hv_kvp device

linux (5.0.0-10.11) disco; urgency=medium

  * linux: 5.0.0-10.11 -proposed tracker (LP: #1823936)

  * Apparmor enforcement failure in lxc selftests (LP: #1823379)
    - SAUCE: apparmor: Restore Y/N in /sys for apparmor's "enabled"

  * systemd cause kernel trace "BUG: unable to handle kernel paging request at
    6db23a14" on Cosmic i386 (LP: #1813244)
    - openvswitch: fix flow actions reallocation

linux (5.0.0-9.10) disco; urgency=medium

  * linux: 5.0.0-9.10 -proposed tracker (LP: #1823228)

  * Packaging resync (LP: #1786013)
    - [Packaging] resync git-ubuntu-log
    - [Packaging] update helper scripts
    - [Packaging] resync retpoline extraction

  * Huawei Hi1822 NIC has poor performance (LP: #1820187)
    - net-next/hinic: replace disable_irq_nosync/enable_irq

  * Add uid shifting overlay filesystem (shiftfs) (LP: #1823186)
    - shiftfs: uid/gid shifting bind mount
    - shiftfs: rework and extend
    - shiftfs: support some btrfs ioctls
    - [Config] enable shiftfs

  * Cannot boot or install - have to use nomodeset (LP: #1821820)
    - Revert "drm/i915/fbdev: Actually configure untiled displays"

  * Disco update: v5.0.6 upstream stable release (LP: #1823060)
    - netfilter: nf_tables: fix set double-free in abort path
    - dccp: do not use ipv6 header for ipv4 flow
    - genetlink: Fix a memory leak on error path
    - gtp: change NET_UDP_TUNNEL dependency to select
    - ipv6: make ip6_create_rt_rcu return ip6_null_entry instead of NULL
    - mac8390: Fix mmio access size probe
    - mISDN: hfcpci: Test both vendor & device ID for Digium HFC4S
    - net: aquantia: fix rx checksum offload for UDP/TCP over IPv6
    - net: datagram: fix unbounded loop in __skb_try_recv_datagram()
    - net/packet: Set __GFP_NOWARN upon allocation in alloc_pg_vec
    - net: phy: meson-gxl: fix interrupt support
    - net: rose: fix a possible stack overflow
    - net: stmmac: fix memory corruption with large MTUs
    - net-sysfs: call dev_hold if kobject_init_and_add success
    - net: usb: aqc111: Extend HWID table by QNAP device
    - packets: Always register packet sk in the same order
    - rhashtable: Still do rehash when we get EEXIST
    - sctp: get sctphdr by offset in sctp_compute_cksum
    - sctp: use memdup_user instead of vmemdup_user
    - tcp: do not use ipv6 header for ipv4 flow
    - tipc: allow servic...