Comment 0 for bug 1854550

"[Steps to reproduce]
Enable memleak, and do as follows:
root@(none)$ echo 0 > /sys/devices/platform/HISI0162:01/host0/port-0:0/expander-0:0/port-0:0:10/phy-0:0:10/sas_phy/phy-0:0:10/enable
[ 79.857888] hisi_sas_v2_hw HISI0162:01: dev[7:1] is gone
root@(none)$ echo scan > /sys/kernel/debug/kmemleak
[ 131.656603] kmemleak: 3 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
root@(none)$ more /sys/kernel/debug/kmemleak
unreferenced object 0xffff041da5c66000 (size 256):
  comm ""kworker/u128:1"", pid 549, jiffies 4294898543 (age 113.728s)
  hex dump (first 32 bytes):
    00 5e c6 a5 1d 04 ff ff 01 00 00 00 00 00 00 00 .^..............
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
  backtrace:
    [<(____ptrval____)>] kmem_cache_alloc+0x188/0x260
    [<(____ptrval____)>] bsg_setup_queue+0x48/0x1a8
    [<(____ptrval____)>] sas_rphy_add+0x108/0x2d0
    [<(____ptrval____)>] sas_probe_devices+0x168/0x208
    [<(____ptrval____)>] sas_discover_domain+0x660/0x9c8
    [<(____ptrval____)>] process_one_work+0x3f8/0x690
    [<(____ptrval____)>] worker_thread+0x70/0x6a0
    [<(____ptrval____)>] kthread+0x1b8/0x1c0
    [<(____ptrval____)>] ret_from_fork+0x10/0x18
unreferenced object 0xffff041d8c075400 (size 128):
  comm ""kworker/u128:1"", pid 549, jiffies 4294898543 (age 113.728s)
  hex dump (first 32 bytes):
    00 40 25 97 1d 00 ff ff 00 00 00 00 00 00 00 00 .@%.............
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
  backtrace:
    [<(____ptrval____)>] __kmalloc_node+0x1a8/0x2c8
    [<(____ptrval____)>] blk_mq_realloc_tag_set_tags.part.70+0x48/0xd8
    [<(____ptrval____)>] blk_mq_alloc_tag_set+0x1dc/0x530
    [<(____ptrval____)>] bsg_setup_queue+0xe8/0x1a8
    [<(____ptrval____)>] sas_rphy_add+0x108/0x2d0
    [<(____ptrval____)>] sas_probe_devices+0x168/0x208
    [<(____ptrval____)>] sas_discover_domain+0x660/0x9c8
    [<(____ptrval____)>] process_one_work+0x3f8/0x690
    [<(____ptrval____)>] worker_thread+0x70/0x6a0
    [<(____ptrval____)>] kthread+0x1b8/0x1c0
    [<(____ptrval____)>] ret_from_fork+0x10/0x18
unreferenced object 0xffff041da5c65e00 (size 256):
  comm ""kworker/u128:1"", pid 549, jiffies 4294898543 (age 113.728s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
  backtrace:
    [<(____ptrval____)>] __kmalloc_node+0x1a8/0x2c8
    [<(____ptrval____)>] blk_mq_alloc_tag_set+0x254/0x530
    [<(____ptrval____)>] bsg_setup_queue+0xe8/0x1a8
    [<(____ptrval____)>] sas_rphy_add+0x108/0x2d0
    [<(____ptrval____)>] sas_probe_devices+0x168/0x208
    [<(____ptrval____)>] sas_discover_domain+0x660/0x9c8
    [<(____ptrval____)>] process_one_work+0x3f8/0x690
    [<(____ptrval____)>] worker_thread+0x70/0x6a0
    [<(____ptrval____)>] kthread+0x1b8/0x1c0
    [<(____ptrval____)>] ret_from_fork+0x10/0x18
root@(none)$

[solution]
Fix by doing the queue removal in one place - in sas_rphy_remove() -
instead of unregistering the queue in sas_rphy_remove() and finally
cleaning up the queue in calling blk_cleanup_queue() from
sas_end_device_release() or sas_expander_release().

Function bsg_remove_queue() can handle a NULL pointer q, so remove the
precheck in sas_rphy_remove().
"
scsi: scsi_transport_sas: Fix memory leak when removing devices