scsi: qedf: Add check for offload before flushing I/Os for target

We need to check that a fcport is offloaded before we try to flush any
requests.  No doing so could lead to undefined results and most likely a
crash.

Fixes the oops:

[  343.971886] [0000:42:00.3]:[qedf_execute_tmf:2070]:8: wait for tm_cmpl timeout!
[  343.971933] BUG: unable to handle kernel paging request at 00000000000024a8
[  343.971949] IP: [<ffffffffa06b8cc6>] qedf_flush_active_ios+0x46/0x260 [qedf]
[  343.971952] PGD 42c569067 PUD 4160fe067 PMD 0
[  343.971954] Oops: 0000 [#1] SMP
[  343.972008] Modules linked in: qedf(OEX) qed(OEX) bnx2i cnic fuse af_packet iscsi_ibft msr xfs intel_rapl sb_edac edac_core x86_pkg_temp_thermal bnx2x geneve intel_powerclamp vxlan coretemp ipmi_ssif ipmi_devintf kvm_intel kvm libiscsi joydev irqbypass crct10dif_pclmul crc32_pclmul ghash_clmulni_intel tg3 ip6_udp_tunnel udp_tunnel mdio libcrc32c iTCO_wdt scsi_transport_iscsi uio drbg iTCO_vendor_support iscsi_boot_sysfs dcdbas(X) ipmi_si ansi_cprng aesni_intel aes_x86_64 lrw gf128mul glue_helper ablk_helper ptp pps_core pcspkr libphy lpc_ich mfd_core cryptd fjes wmi ipmi_msghandler button crc8 libfcoe libfc scsi_transport_fc mei_me mei shpchp processor acpi_pad btrfs xor hid_generic usbhid raid6_pq sd_mod sr_mod cdrom mgag200 crc32c_intel i2c_algo_bit drm_kms_helper syscopyarea sysfillrect sysimgblt
[  343.972020]  fb_sys_fops ttm ahci ehci_pci libahci ehci_hcd drm libata usbcore megaraid_sas usb_common sg dm_multipath dm_mod scsi_dh_rdac scsi_dh_emc scsi_dh_alua scsi_mod autofs4 [last unloaded: qedf]
[  343.972022] Supported: Yes, External
[  343.972026] CPU: 30 PID: 12777 Comm: sg_reset Tainted: G        W  OE    X 4.4.73-5-default #1
[  343.972027] Hardware name: Dell Inc. PowerEdge R720/0X3D66, BIOS 2.1.3 11/20/2013
[  343.972029] task: ffff88018dfc0e80 ti: ffff88042bd7c000 task.ti: ffff88042bd7c000
[  343.972036] RIP: 0010:[<ffffffffa06b8cc6>]  [<ffffffffa06b8cc6>] qedf_flush_active_ios+0x46/0x260 [qedf]
[  343.972038] RSP: 0018:ffff88042bd7fbe0  EFLAGS: 00010286
[  343.972039] RAX: 0000000000000000 RBX: ffff88042ce37800 RCX: 0000000000000400
[  343.972040] RDX: 000000000000060e RSI: ffffffffa06be830 RDI: ffff8807e5072cc0
[  343.972041] RBP: 0000000000001000 R08: ffffffffa06bff4d R09: ffff88018dd84580
[  343.972042] R10: 000000000000018b R11: 0000000000000002 R12: 0000000000002003
[  343.972043] R13: 0000000000000000 R14: 0000000000000000 R15: ffff8807e5072cc0
[  343.972046] FS:  00007fc1c8809700(0000) GS:ffff88042fbc0000(0000) knlGS:0000000000000000
[  343.972048] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  343.972049] CR2: 00000000000024a8 CR3: 00000004236ec000 CR4: 00000000001406e0
[  343.972050] Stack:
[  343.972053]  504c78750607e154 ffffffff810a7d10 ffff88042ce37800 0000000000000010
[  343.972055]  0000000000002003 ffff8807ff480c48 ffff8807e5072cc0 ffffc90004ec4ff8
[  343.972057]  ffffffffa06b9b86 ffff880800000010 0000000000000282 ffff88042ce37800
[  343.972058] Call Trace:
[  343.972094]  [<ffffffffa06b9b86>] qedf_initiate_tmf+0x346/0x3e0 [qedf]
[  343.972120]  [<ffffffffa000fa06>] scsi_try_bus_device_reset+0x26/0x40 [scsi_mod]
[  343.972133]  [<ffffffffa001038e>] scsi_ioctl_reset+0x13e/0x260 [scsi_mod]
[  343.972145]  [<ffffffffa000f416>] scsi_ioctl+0x136/0x3d0 [scsi_mod]
[  343.972154]  [<ffffffff812ff6eb>] blkdev_ioctl+0x6bb/0x950
[  343.972164]  [<ffffffff8123cfed>] block_ioctl+0x3d/0x40
[  343.972170]  [<ffffffff81217e2d>] do_vfs_ioctl+0x2cd/0x4a0
[  343.972186]  [<ffffffff81218074>] SyS_ioctl+0x74/0x80
[  343.972193]  [<ffffffff8160916e>] entry_SYSCALL_64_fastpath+0x12/0x6d
[  343.975285] DWARF2 unwinder stuck at entry_SYSCALL_64_fastpath+0x12/0x6d
Signed-off-by: Chad Dupuis <chad.dupuis@cavium.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/qedf/qedf_io.c

@@ -1414,6 +1414,12 @@ void qedf_flush_active_ios(struct qedf_rport *fcport, int lun)
 	if (!fcport)
 		return;
 
+	/* Check that fcport is still offloaded */
+	if (!test_bit(QEDF_RPORT_SESSION_READY, &fcport->flags)) {
+		QEDF_ERR(NULL, "fcport is no longer offloaded.\n");
+		return;
+	}
+
 	qedf = fcport->qedf;
 	cmd_mgr = qedf->cmd_mgr;