scsi: ibmvfc: Allocate/free queue resource only during probe/remove

Summary

In the Linux kernel, the following vulnerability has been resolved: scsi: ibmvfc: Allocate/free queue resource only during probe/remove Currently, the sub-queues and event pool resources are allocated/freed for every CRQ connection event such as reset and LPM. This exposes the driver to a couple issues. First the inefficiency of freeing and reallocating memory that can simply be resued after being sanitized. Further, a system under memory pressue runs the risk of allocation failures that could result in a crippled driver. Finally, there is a race window where command submission/compeletion can try to pull/return elements from/to an event pool that is being deleted or already has been deleted due to the lack of host state around freeing/allocating resources. The following is an example of list corruption following a live partition migration (LPM): Oops: Exception in kernel mode, sig: 5 [#1] LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries Modules linked in: vfat fat isofs cdrom ext4 mbcache jbd2 nft_counter nft_compat nf_tables nfnetlink rpadlpar_io rpaphp xsk_diag nfsv3 nfs_acl nfs lockd grace fscache netfs rfkill bonding tls sunrpc pseries_rng drm drm_panel_orientation_quirks xfs libcrc32c dm_service_time sd_mod t10_pi sg ibmvfc scsi_transport_fc ibmveth vmx_crypto dm_multipath dm_mirror dm_region_hash dm_log dm_mod ipmi_devintf ipmi_msghandler fuse CPU: 0 PID: 2108 Comm: ibmvfc_0 Kdump: loaded Not tainted 5.14.0-70.9.1.el9_0.ppc64le #1 NIP: c0000000007c4bb0 LR: c0000000007c4bac CTR: 00000000005b9a10 REGS: c00000025c10b760 TRAP: 0700 Not tainted (5.14.0-70.9.1.el9_0.ppc64le) MSR: 800000000282b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE> CR: 2800028f XER: 0000000f CFAR: c0000000001f55bc IRQMASK: 0 GPR00: c0000000007c4bac c00000025c10ba00 c000000002a47c00 000000000000004e GPR04: c0000031e3006f88 c0000031e308bd00 c00000025c10b768 0000000000000027 GPR08: 0000000000000000 c0000031e3009dc0 00000031e0eb0000 0000000000000000 GPR12: c0000031e2ffffa8 c000000002dd0000 c000000000187108 c00000020fcee2c0 GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 GPR20: 0000000000000000 0000000000000000 0000000000000000 c008000002f81300 GPR24: 5deadbeef0000100 5deadbeef0000122 c000000263ba6910 c00000024cc88000 GPR28: 000000000000003c c0000002430a0000 c0000002430ac300 000000000000c300 NIP [c0000000007c4bb0] __list_del_entry_valid+0x90/0x100 LR [c0000000007c4bac] __list_del_entry_valid+0x8c/0x100 Call Trace: [c00000025c10ba00] [c0000000007c4bac] __list_del_entry_valid+0x8c/0x100 (unreliable) [c00000025c10ba60] [c008000002f42284] ibmvfc_free_queue+0xec/0x210 [ibmvfc] [c00000025c10bb10] [c008000002f4246c] ibmvfc_deregister_scsi_channel+0xc4/0x160 [ibmvfc] [c00000025c10bba0] [c008000002f42580] ibmvfc_release_sub_crqs+0x78/0x130 [ibmvfc] [c00000025c10bc20] [c008000002f4f6cc] ibmvfc_do_work+0x5c4/0xc70 [ibmvfc] [c00000025c10bce0] [c008000002f4fdec] ibmvfc_work+0x74/0x1e8 [ibmvfc] [c00000025c10bda0] [c0000000001872b8] kthread+0x1b8/0x1c0 [c00000025c10be10] [c00000000000cd64] ret_from_kernel_thread+0x5c/0x64 Instruction dump: 40820034 38600001 38210060 4e800020 7c0802a6 7c641b78 3c62fe7a 7d254b78 3863b590 f8010070 4ba309cd 60000000 <0fe00000> 7c0802a6 3c62fe7a 3863b640 ---[ end trace 11a2b65a92f8b66c ]--- ibmvfc 30000003: Send warning. Receive queue closed, will retry. Add registration/deregistration helpers that are called instead during connection resets to sanitize and reconfigure the queues.