path: root/drivers/target/loopback/tcm_loop.c

/*******************************************************************************
 *
 * This file contains the Linux/SCSI LLD virtual SCSI initiator driver
 * for emulated SAS initiator ports
 *
 * © Copyright 2011 RisingTide Systems LLC.
 *
 * Licensed to the Linux Foundation under the General Public License (GPL) version 2.
 *
 * Author: Nicholas A. Bellinger <nab@risingtidesystems.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 ****************************************************************************/

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/configfs.h>
#include <scsi/scsi.h>
#include <scsi/scsi_tcq.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_cmnd.h>

#include <target/target_core_base.h>
#include <target/target_core_transport.h>
#include <target/target_core_fabric_ops.h>
#include <target/target_core_fabric_configfs.h>
#include <target/target_core_fabric_lib.h>
#include <target/target_core_configfs.h>
#include <target/target_core_device.h>
#include <target/target_core_tpg.h>
#include <target/target_core_tmr.h>

#include "tcm_loop.h"

#define to_tcm_loop_hba(hba)	container_of(hba, struct tcm_loop_hba, dev)

/* Local pointer to allocated TCM configfs fabric module */
static struct target_fabric_configfs *tcm_loop_fabric_configfs;

static struct kmem_cache *tcm_loop_cmd_cache;

static int tcm_loop_hba_no_cnt;

/*
 * Allocate a tcm_loop cmd descriptor from target_core_mod code
 *
 * Can be called from interrupt context in tcm_loop_queuecommand() below
 */
static struct se_cmd *tcm_loop_allocate_core_cmd(
	struct tcm_loop_hba *tl_hba,
	struct se_portal_group *se_tpg,
	struct scsi_cmnd *sc)
{
	struct se_cmd *se_cmd;
	struct se_session *se_sess;
	struct tcm_loop_nexus *tl_nexus = tl_hba->tl_nexus;
	struct tcm_loop_cmd *tl_cmd;
	int sam_task_attr;

	if (!tl_nexus) {
		scmd_printk(KERN_ERR, sc, "TCM_Loop I_T Nexus"
				" does not exist\n");
		set_host_byte(sc, DID_ERROR);
		return NULL;
	}
	se_sess = tl_nexus->se_sess;

	tl_cmd = kmem_cache_zalloc(tcm_loop_cmd_cache, GFP_ATOMIC);
	if (!tl_cmd) {
		printk(KERN_ERR "Unable to allocate struct tcm_loop_cmd\n");
		set_host_byte(sc, DID_ERROR);
		return NULL;
	}
	se_cmd = &tl_cmd->tl_se_cmd;
	/*
	 * Save the pointer to struct scsi_cmnd *sc
	 */
	tl_cmd->sc = sc;
	/*
	 * Locate the SAM Task Attr from struct scsi_cmnd *
	 */
	if (sc->device->tagged_supported) {
		switch (sc->tag) {
		case HEAD_OF_QUEUE_TAG:
			sam_task_attr = MSG_HEAD_TAG;
			break;
		case ORDERED_QUEUE_TAG:
			sam_task_attr = MSG_ORDERED_TAG;
			break;
		default:
			sam_task_attr = MSG_SIMPLE_TAG;
			break;
		}
	} else
		sam_task_attr = MSG_SIMPLE_TAG;

	/*
	 * Initialize struct se_cmd descriptor from target_core_mod infrastructure
	 */
	transport_init_se_cmd(se_cmd, se_tpg->se_tpg_tfo, se_sess,
			scsi_bufflen(sc), sc->sc_data_direction, sam_task_attr,
			&tl_cmd->tl_sense_buf[0]);

	/*
	 * Signal BIDI usage with T_TASK(cmd)->t_tasks_bidi
	 */
	if (scsi_bidi_cmnd(sc))
		se_cmd->t_tasks_bidi = 1;
	/*
	 * Locate the struct se_lun pointer and attach it to struct se_cmd
	 */
	if (transport_lookup_cmd_lun(se_cmd, tl_cmd->sc->device->lun) < 0) {
		kmem_cache_free(tcm_loop_cmd_cache, tl_cmd);
		set_host_byte(sc, DID_NO_CONNECT);
		return NULL;
	}

	return se_cmd;
}

/*
 * Called by struct target_core_fabric_ops->new_cmd_map()
 *
 * Always called in process context.  A non zero return value
 * here will signal to handle an exception based on the return code.
 */
static int tcm_loop_new_cmd_map(struct se_cmd *se_cmd)
{
	struct tcm_loop_cmd *tl_cmd = container_of(se_cmd,
				struct tcm_loop_cmd, tl_se_cmd);
	struct scsi_cmnd *sc = tl_cmd->sc;
	struct scatterlist *sgl_bidi = NULL;
	u32 sgl_bidi_count = 0;
	int ret;
	/*
	 * Allocate the necessary tasks to complete the received CDB+data
	 */
	ret = transport_generic_allocate_tasks(se_cmd, sc->cmnd);
	if (ret == -ENOMEM) {
		/* Out of Resources */
		return PYX_TRANSPORT_LU_COMM_FAILURE;
	} else if (ret == -EINVAL) {
		/*
		 * Handle case for SAM_STAT_RESERVATION_CONFLICT
		 */
		if (se_cmd->se_cmd_flags & SCF_SCSI_RESERVATION_CONFLICT)
			return PYX_TRANSPORT_RESERVATION_CONFLICT;
		/*
		 * Otherwise, return SAM_STAT_CHECK_CONDITION and return
		 * sense data.
		 */
		return PYX_TRANSPORT_USE_SENSE_REASON;
	}

	/*
	 * For BIDI commands, pass in the extra READ buffer
	 * to transport_generic_map_mem_to_cmd() below..
	 */
	if (se_cmd->t_tasks_bidi) {
		struct scsi_data_buffer *sdb = scsi_in(sc);

		sgl_bidi = sdb->table.sgl;
		sgl_bidi_count = sdb->table.nents;
	}

	/* Tell the core about our preallocated memory */
	ret = transport_generic_map_mem_to_cmd(se_cmd, scsi_sglist(sc),
			scsi_sg_count(sc), sgl_bidi, sgl_bidi_count);
	if (ret < 0)
		return PYX_TRANSPORT_LU_COMM_FAILURE;

	return 0;
}

/*
 * Called from struct target_core_fabric_ops->check_stop_free()
 */
static void tcm_loop_check_stop_free(struct se_cmd *se_cmd)
{
	/*
	 * Do not release struct se_cmd's containing a valid TMR
	 * pointer.  These will be released directly in tcm_loop_device_reset()
	 * with transport_generic_free_cmd().
	 */
	if (se_cmd->se_tmr_req)
		return;
	/*
	 * Release the struct se_cmd, which will make a callback to release
	 * struct tcm_loop_cmd * in tcm_loop_deallocate_core_cmd()
	 */
	transport_generic_free_cmd(se_cmd, 0, 0);
}

static void tcm_loop_release_cmd(struct se_cmd *se_cmd)
{
	struct tcm_loop_cmd *tl_cmd = container_of(se_cmd,
				struct tcm_loop_cmd, tl_se_cmd);

	kmem_cache_free(tcm_loop_cmd_cache, tl_cmd);
}

static int tcm_loop_proc_info(struct Scsi_Host *host, char *buffer,
				char **start, off_t offset,
				int length, int inout)
{
	return sprintf(buffer, "tcm_loop_proc_info()\n");
}

static int tcm_loop_driver_probe(struct device *);
static int tcm_loop_driver_remove(struct device *);

static int pseudo_lld_bus_match(struct device *dev,
				struct device_driver *dev_driver)
{
	return 1;
}

static struct bus_type tcm_loop_lld_bus = {
	.name			= "tcm_loop_bus",
	.match			= pseudo_lld_bus_match,
	.probe			= tcm_loop_driver_probe,
	.remove			= tcm_loop_driver_remove,
};

static struct device_driver tcm_loop_driverfs = {
	.name			= "tcm_loop",
	.bus			= &tcm_loop_lld_bus,
};
/*
 * Used with root_device_register() in tcm_loop_alloc_core_bus() below
 */
struct device *tcm_loop_primary;

/*
 * Copied from drivers/scsi/libfc/fc_fcp.c:fc_change_queue_depth() and
 * drivers/scsi/libiscsi.c:iscsi_change_queue_depth()
 */
static int tcm_loop_change_queue_depth(
	struct scsi_device *sdev,
	int depth,
	int reason)
{
	switch (reason) {
	case SCSI_QDEPTH_DEFAULT:
		scsi_adjust_queue_depth(sdev, scsi_get_tag_type(sdev), depth)