[SCSI] qla2xxx: Explicitly tear-down vports during PCI remove_one().

During internal testing, we've seen issues (hangs) with the
'deferred' vport tear-down-processing typically accompanied with
the fc_remove_host() call. This is due to the current
implementation's back-end vport handling being performed by the
physical-HA's DPC thread where premature shutdown could lead to
latent vport requests without a processor.

This should also address a problem reported by Gal Rosen
(http://marc.info/?l=linux-scsi&m=121731664417358&w=2) where the
driver would attempt to awaken a previously torn-down DPC thread
from interrupt context by implicitly calling wake_up_process()
rather than the driver's qla2xxx_wake_dpc() helper. Rather, than
reshuffle the remove_one() device-removal code, during unload,
depend on the driver's timer to wake-up the DPC process, by
limiting wake-ups based on an 'unloading' flag.

Signed-off-by: Andrew Vasquez <[e-mail]>
Signed-off-by: James Bottomley <[e-mail]>

drivers/scsi/qla2xxx/qla_def.h

···
 #define REGISTER_FDMI_NEEDED	26
 #define FCPORT_UPDATE_NEEDED	27
 #define VP_DPC_NEEDED		28	/* wake up for VP dpc handling */
+#define UNLOADING		29
 
 	uint32_t	device_flags;
 #define DFLG_LOCAL_DEVICES		BIT_0

drivers/scsi/qla2xxx/qla_mbx.c

···
 		set_bit(VP_IDX_ACQUIRED, &vha->vp_flags);
 		set_bit(VP_DPC_NEEDED, &ha->dpc_flags);
 
-		wake_up_process(ha->dpc_thread);
+		qla2xxx_wake_dpc(ha);
 	}
 }
 

drivers/scsi/qla2xxx/qla_os.c

···
 static void
 qla2x00_remove_one(struct pci_dev *pdev)
 {
-	scsi_qla_host_t *ha;
+	scsi_qla_host_t *ha, *vha, *temp;
 
 	ha = pci_get_drvdata(pdev);
+
+	list_for_each_entry_safe(vha, temp, &ha->vp_list, vp_list)
+		fc_vport_terminate(vha->fc_vport);
+
+	set_bit(UNLOADING, &ha->dpc_flags);
 
 	qla2x00_dfs_remove(ha);
 
···
 void
 qla2xxx_wake_dpc(scsi_qla_host_t *ha)
 {
-	if (ha->dpc_thread)
-		wake_up_process(ha->dpc_thread);
+	struct task_struct *t = ha->dpc_thread;
+
+	if (!test_bit(UNLOADING, &ha->dpc_flags) && t)
+		wake_up_process(t);
 }
 
 /*