[powerpc] WARN at drivers/scsi/sg.c:2236 (sg_remove_sfp_usercontext)

[Sachin Sant]

> Can you check the debug patch below and provide output?
> When I'm right the warning should be gone and you should just get the
> "Modification triggered" instead. When I'm wrong we should at least see,
> how many references d_ref has left.
> 

With the debug patch applied, code says d_ref value is 2

# ./ioctl_sg01 
tst_test.c:1741: TINFO: LTP version: 20210524-2511-g00b497c47
tst_test.c:1625: TINFO: Timeout per run is 1h 00m 30s
ioctl_sg01.c:83: TINFO: Found SCSI device /dev/sg0
[   36.016630] ------------[ cut here ]------------
[   36.016674] WARNING: CPU: 19 PID: 460 at drivers/scsi/sg.c:2238 sg_remove_sfp_usercontext+0x270/0x298 [sg]
[   36.016707] Modules linked in: rpadlpar_io rpaphp xsk_diag nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct nft_chain_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 bonding tls rfkill ip_set nf_tables nfnetlink sunrpc binfmt_misc pseries_rng vmx_crypto xfs libcrc32c sd_mod sr_mod t10_pi crc64_rocksoft_generic cdrom crc64_rocksoft crc64 sg ibmvscsi scsi_transport_srp ibmveth fuse
[   36.016834] CPU: 19 PID: 460 Comm: kworker/19:1 Kdump: loaded Not tainted 6.9.0-rc1-next-20240328-dirty #3
[   36.016849] Hardware name: IBM,9080-HEX POWER10 (raw) 0x800200 0xf000006 of:IBM,FW1060.00 (NH1060_018) hv:phyp pSeries
[   36.016868] Workqueue: events sg_remove_sfp_usercontext [sg]
[   36.016889] NIP:  c008000015cf4110 LR: c008000015cf4000 CTR: c0000000005393b0
[   36.016903] REGS: c00000009414fae0 TRAP: 0700   Not tainted  (6.9.0-rc1-next-20240328-dirty)
[   36.016921] MSR:  800000000282b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE>  CR: 44000448  XER: 00000000
[   36.016962] CFAR: c008000015cf400c IRQMASK: 0  [   36.016962] GPR00: c008000015cf4000 c00000009414fd80 c008000015d18900 0000000000000000  [   36.016962] GPR04: 00000000c0000000 0000000000000023 c000000008dee000 0000000000000022  [   36.016962] GPR08: 000000038a6d0000 0000000000000002 0000000000000000 c008000015cf8c10  [   36.016962] GPR12: c0000000005393b0 c00000038ffe8b00 c0000000001a2bac c000000008e4e980  [   36.016962] GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000  [   36.016962] GPR20: c00000038c993b00 c000000008dea030 c000000008dea000 c0000000a2712000  [   36.016962] GPR24: 0000000000000000 c00000000c3bd380 c0000000045ab205 c000000008deb330  [   36.016962] GPR28: c00000038c993b00 c000000008dea080 c000000008deb328 c00000000c3bd418  [   36.017107] NIP [c008000015cf4110] sg_remove_sfp_usercontext+0x270/0x298 [sg]
[   36.017129] LR [c008000015cf4000] sg_remove_sfp_usercontext+0x160/0x298 [sg]
[   36.017144] Call Trace:
[   36.017148] [c00000009414fd80] [c008000015cf4000] sg_remove_sfp_usercontext+0x160/0x298 [sg] (unreliable)
[   36.017169] [c00000009414fe40] [c00000000019337c] process_one_work+0x20c/0x4f4
[   36.017189] [c00000009414fef0] [c0000000001942fc] worker_thread+0x378/0x544
[   36.017208] [c00000009414ff90] [c0000000001a2cdc] kthread+0x138/0x140
[   36.017225] [c00000009414ffe0] [c00000000000df98] start_kernel_thread+0x14/0x18
[   36.017241] Code: 3bf90098 e8c98310 3d220000 e8698010 48004509 e8410018 7ec3b378 48004b15 e8410018 81390098 2c090001 4182ff04 <0fe00000> 80990098 3d220000 78840020  [   36.017289] ---[ end trace 0000000000000000 ]---
[   36.017302] d_ref=2
ioctl_sg01.c:124: TPASS: Output buffer is empty, no data leaked
[   44.707319] d_ref=2

Summary:
passed   1
failed   0
broken   0
skipped  0
warnings 0


— Sachin