<commit_before>/*
 * Copyright(c) 2007 Intel Corporation. All rights reserved.
 * Copyright(c) 2008 Red Hat, Inc.  All rights reserved.
 * Copyright(c) 2008 <NAME>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope 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.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Maintained at www.Open-FCoE.org
 */

#include <linux/module.h>
#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/spinlock.h>
#include <linux/scatterlist.h>
#include <linux/err.h>
#include <linux/crc32.h>
#include <linux/slab.h>

#include <scsi/scsi_tcq.h>
#include <scsi/scsi.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_cmnd.h>

#include <scsi/fc/fc_fc2.h>

#include <scsi/libfc.h>
#include <scsi/fc_encode.h>

#include "fc_libfc.h"

static struct kmem_cache *scsi_pkt_cachep;

/* SRB state definitions */
#define FC_SRB_FREE		0		/* cmd is free */
#define FC_SRB_CMD_SENT		(1 << 0)	/* cmd has been sent */
#define FC_SRB_RCV_STATUS	(1 << 1)	/* response has arrived */
#define FC_SRB_ABORT_PENDING	(1 << 2)	/* cmd abort sent to device */
#define FC_SRB_ABORTED		(1 << 3)	/* abort acknowledged */
#define FC_SRB_DISCONTIG	(1 << 4)	/* non-sequential data recvd */
#define FC_SRB_COMPL		(1 << 5)	/* fc_io_compl has been run */
#define FC_SRB_FCP_PROCESSING_TMO (1 << 6)	/* timer function processing */

#define FC_SRB_READ		(1 << 1)
#define FC_SRB_WRITE		(1 << 0)

/* constant added to e_d_tov timeout to get rec_tov value */
#define REC_TOV_CONST		1

/*
 * The SCp.ptr should be tested and set under the scsi_pkt_queue lock
 */
#define CMD_SP(Cmnd)		    ((struct fc_fcp_pkt *)(Cmnd)->SCp.ptr)
#define CMD_ENTRY_STATUS(Cmnd)	    ((Cmnd)->SCp.have_data_in)
#define CMD_COMPL_STATUS(Cmnd)	    ((Cmnd)->SCp.this_residual)
#define CMD_SCSI_STATUS(Cmnd)	    ((Cmnd)->SCp.Status)
#define CMD_RESID_LEN(Cmnd)	    ((Cmnd)->SCp.buffers_residual)

/**
 * struct fc_fcp_internal - FCP layer internal data
 * @scsi_pkt_pool: Memory pool to draw FCP packets from
 * @scsi_queue_lock: Protects the scsi_pkt_queue
 * @scsi_pkt_queue: Current FCP packets
 * @last_can_queue_ramp_down_time: ramp down time
 * @last_can_queue_ramp_up_time: ramp up time
 * @max_can_queue: max can_queue size
 */
struct fc_fcp_internal {
	mempool_t		*scsi_pkt_pool;
	spinlock_t		scsi_queue_lock;
	struct list_head	scsi_pkt_queue;
	unsigned long		last_can_queue_ramp_down_time;
	unsigned long		last_can_queue_ramp_up_time;
	int			max_can_queue;
};

#define fc_get_scsi_internal(x)	((struct fc_fcp_internal *)(x)->scsi_priv)

/*
 * function prototypes
 * FC scsi I/O related functions
 */
static void fc_fcp_recv_data(struct fc_fcp_pkt *, struct fc_frame *);
static void fc_fcp_recv(struct fc_seq *, struct fc_frame *, void *);
static void fc_fcp_resp(struct fc_fcp_pkt *, struct fc_frame *);
static void fc_fcp_complete_locked(struct fc_fcp_pkt *);
static void fc_tm_done(struct fc_seq *, struct fc_frame *, void *);
static void fc_fcp_error(struct fc_fcp_pkt *, struct fc_frame *);
static void fc_fcp_recovery(struct fc_fcp_pkt *, u8 code);
static void fc_fcp_timeout(unsigned long);
static void fc_fcp_rec(struct fc_fcp_pkt *);
static void fc_fcp_rec_error(struct fc_fcp_pkt *, struct fc_frame *);
static void fc_fcp_rec_resp(struct fc_seq *, struct fc_frame *, void *);
static void fc_io_compl(struct fc_fcp_pkt *);

static void fc_fcp_srr(struct fc_fcp_pkt *, enum fc_rctl, u32);
static void fc_fcp_srr_resp(struct fc_seq *, struct fc_frame *, void *);
static void fc_fcp_srr_error(struct fc_fcp_pkt *, struct fc_frame *);

/*
 * command status codes
 */
#define FC_COMPLETE		0
#define FC_CMD_ABORTED		1
#define FC_CMD_RESET		2
#define FC_CMD_PLOGO		3
#define FC_SNS_RCV		4
#define FC_TRANS_ERR		5
#define FC_DATA_OVRRUN		6
#define FC_DATA_UNDRUN		7
#define FC_ERROR		8
#define FC_HRD_ERROR		9
#define FC_CRC_ERROR		10
#define FC_TIMED_OUT		11

/*
 * Error recovery timeout values.
 */
#define FC_SCSI_TM_TOV		(10 * HZ)
#define FC_HOST_RESET_TIMEOUT	(30 * HZ)
#define FC_CAN_QUEUE_PERIOD	(60 * HZ)

#define FC_MAX_ERROR_CNT	5
#define FC_MAX_RECOV_RETRY	3

#define FC_FCP_DFLT_QUEUE_DEPTH 32

/**
 * fc_fcp_pkt_alloc() - Allocate a fcp_pkt
 * @lport: The local port that the FCP packet is for
 * @gfp:   GFP flags for allocation
 *
 * Return value: fcp_pkt structure or null on allocation failure.
 * Context:	 Can be called from process context, no lock is required.
 */
static struct fc_fcp_pkt *fc_fcp_pkt_alloc(struct fc_lport *lport, gfp_t gfp)
{
	struct fc_fcp_internal *si = fc_get_scsi_internal(lport);
	struct fc_fcp_pkt *fsp;

	fsp = mempool_alloc(si->scsi_pkt_pool, gfp);
	if (fsp) {
		memset(fsp, 0, sizeof(*fsp));
		fsp->lp = lport;
		fsp->xfer_ddp = FC_XID_UNKNOWN;
		atomic_set(&fsp->ref_cnt, 1);
		init_timer(&fsp->timer);
		INIT_LIST_HEAD(&fsp->list);
		spin_lock_init(&fsp->scsi_pkt_lock);
	}
	return fsp;
}

/**
 * fc_fcp_pkt_release() - Release hold on a fcp_pkt
 * @fsp: The FCP packet to be released
 *
 * Context: Can be called from process or interrupt context,
 *	    no lock is required.
 */
static void fc_fcp_pkt_release(struct fc_fcp_pkt *fsp)
{
	if (atomic_dec_and_test(&fsp->ref_cnt)) {
		struct fc_fcp_internal *si = fc_get_scsi_internal(fsp->lp);

		mempool_free(fsp, si->scsi_pkt_pool);
	}
}

/**
 * fc_fcp_pkt_hold() - Hold a fcp_pkt
 * @fsp: The FCP packet to be held
 */
static void fc_fcp_pkt_hold(struct fc_fcp_pkt *fsp)
{
	atomic_inc(&fsp->ref_cnt);
}

/**
 * fc_fcp_pkt_destory() - Release hold on a fcp_pkt
 * @seq: The sequence that the FCP packet is on (required by destructor API)
 * @fsp: The FCP packet to be released
 *
 * This routine is called by a destructor callback in the exch_seq_send()
 * routine of the libfc Transport Template. The 'struct fc_seq' is a required
 * argument even though it is not used by this routine.
 *
 * Context: No locking required.
 */
static void fc_fcp_pkt_destroy(struct fc_seq *seq, void *fsp)
{
	fc_fcp_pkt_release(fsp);
}

/**
 * fc_fcp_lock_pkt() - Lock a fcp_pkt and increase its reference count
 * @fsp: The FCP packet to be locked and incremented
 *
 * We should only return error if we return a command to SCSI-ml before
 * getting a response. This can happen in cases where we send a abort, but
 * do not wait for the response and the abort and command can be passing
 * each other on the wire/network-layer.
 *
 * Note: this function locks the packet and gets a reference to allow
 * callers to call the completion function while the lock is held and
 * not have to worry about the packets refcount.
 *
 * TODO: Maybe we should just have callers grab/release the lock and
 * have a function that they call to verify the fsp and grab a ref if
 * needed.
 */
static inline int fc_fcp_lock_pkt(struct fc_fcp_pkt *fsp)
{
	spin_lock_bh(&fsp->scsi_pkt_lock);
	if (fsp->state & FC_SRB_COMPL) {
		spin_unlock_bh(&fsp->scsi_pkt_lock);
		return -EPERM;
	}

	fc_fcp_pkt_hold(fsp);
	return 0;
}

/**
 * fc_fcp_unlock_pkt() - Release a fcp_pkt's lock and decrement its
 *			 reference count
 * @fsp: The FCP packet to be unlocked and decremented
 */
static inline void fc_fcp_unlock_pkt(struct fc_fcp_pkt *fsp)
{
	spin_unlock_bh(&fsp->scsi_pkt_lock);
	fc_fcp_pkt_release(fsp);
}

/**
 * fc_fcp_timer_set() - Start a timer for a fcp_pkt
 * @fsp:   The FCP packet to start a timer for
 * @delay: The timeout period for the timer
 */
static void fc_fcp_timer_set(struct fc_fcp_pkt *fsp, unsigned long delay)
{
	if (!(fsp->state & FC_SRB_COMPL))
		mod_timer(&fsp->timer, jiffies + delay);
}

/**
 * fc_fcp_send_abort() - Send an abort for exchanges associated with a
 *			 fcp_pkt
 * @fsp: The FCP packet to abort exchanges on
 */
static int fc_fcp_send_abort(struct fc_fcp_pkt *fsp)
{
	if (!fsp->seq_ptr)
		return -EINVAL;

	fsp->state |= FC_SRB_ABORT_PENDING;
	return fsp->lp->tt.seq_exch_abort(fsp->seq_ptr, 0);
}

/**
 * fc_fcp_retry_cmd() - Retry a fcp_pkt
 * @fsp: The FCP packet to be retried
 *
 * Sets the status code to be FC_ERROR and then calls
 * fc_fcp_complete_locked() which in turn calls fc_io_compl().
 * fc_io_compl() will notify the SCSI-ml that the I/O is done.
 * The SCSI-ml will retry the command.
 */
static void fc_fcp_retry_cmd(struct fc_fcp_pkt *fsp)
{
	if (fsp->seq_ptr) {
		fsp->lp->tt.exch_done(fsp->seq_ptr);
		fsp->seq_ptr = NULL;
	}

	fsp->state &= ~FC_SRB_ABORT_PENDING;
	fsp->io_status = 0;
	fsp->status_code = FC_ERROR;
	fc_fcp_complete_locked(fsp);
}

/**
 * fc_fcp_ddp_setup() - Calls a LLD's ddp_setup routine to set up DDP context
 * @fsp: The FCP packet that will manage the DDP frames
 * @xid: The XID that will be used for the DDP exchange
 */
void fc_fcp_ddp_setup(struct fc_fcp_pkt *fsp, u16 xid)
{
	struct fc_lport *lport;

	lport = fsp->lp;
	if ((fsp->req_flags & FC_SRB_READ) &&
	    (lport->lro_enabled) && (lport->tt.ddp_setup)) {
		if (lport->tt.ddp_setup(lport, xid, scsi_sglist(fsp->cmd),
					scsi_sg_count(fsp->cmd)))
			fsp->xfer_ddp = xid;
	}
}

/**
 * fc_fcp_ddp_done() - Calls a LLD's ddp_done routine to release any
 *		       DDP related resources for a fcp_pkt
 * @fsp: The FCP packet that DDP had been used on
 */
static void fc_fcp_ddp_done(struct fc_fcp_pkt *fsp)
{
	struct fc_lport *lport;

	if (!fsp)
		return;

	if (fsp->xfer_ddp == FC_XID_UNKNOWN)
		return;

	lport = fsp->lp;
	if (lport->tt.ddp_done) {
		fsp->xfer_len = lport->tt.ddp_done(lport, fsp->xfer_ddp);
		fsp->xfer_ddp = FC_XID_UNKNOWN;
	}
}

/**
 * fc_fcp_can_queue_ramp_up() - increases can_queue
 * @lport: lport to ramp up can_queue
 *
 * Locking notes: Called with Scsi_Host lock held
 */
static void fc_fcp_can_queue_ramp_up(struct fc_lport *lport)
{
	struct fc_fcp_internal *si = fc_get_scsi_internal(lport);
	int can_queue;

	if (si->last_can_queue_ramp_up_time &&
	    (time_before(jiffies, si->last_can_queue_ramp_up_time +
			 FC_CAN_QUEUE_PERIOD)))
		return;

	if (time_before(jiffies, si->last_can_queue_ramp_down_time +
			FC_CAN_QUEUE_PERIOD))
		return;

	si->last_can_queue_ramp_up_time = jiffies;

	can_queue = lport->host->can_queue << 1;
	if (can_queue >= si->max_can_queue) {
		can_queue = si->max_can_queue;
		si->last_can_queue_ramp_down_time = 0;
	}
	lport->host->can_queue = can_queue;
	shost_printk(KERN_ERR, lport->host, "libfc: increased "
		     "can_queue to %d.\n", can_queue);
}

/**
 * fc_fcp_can_queue_ramp_down() - reduces can_queue
 * @lport: lport to reduce can_queue
 *
 * If we are getting memory allocation failures, then we may
 * be trying to execute too many commands. We let the running
 * commands complete or timeout, then try again with a reduced
 * can_queue. Eventually we will hit the point where we run
 * on all reserved structs.
 *
 * Locking notes: Called with Scsi_Host lock held
 */
static void fc_fcp_can_queue_ramp_down(struct fc_lport *lport)
{
	struct fc_fcp_internal *si = fc_get_scsi_internal(lport);
	int can_queue;

	if (si->last_can_queue_ramp_down_time &&
	    (time_before(jiffies, si->last_can_queue_ramp_down_time +
			 FC_CAN_QUEUE_PERIOD)))
		return;

	si->last_can_queue_ramp_down_time = jiffies;

	can_queue = lport->host->can_queue;
	can_queue >>= 1;
	if (!can_queue)
		can_queue = 1;
	lport->host->can_queue = can_queue;
	shost_printk(KERN_ERR, lport->host, "libfc: Could not allocate frame.\n"
		     "Reducing can_queue to %d.\n", can_queue);
}

/*
 * fc_fcp_frame_alloc() -  Allocates fc_frame structure and buffer.
 * @lport:	fc lport struct
 * @len:	payload length
 *
 * Allocates fc_frame structure and buffer but if fails to allocate
 * then reduce can_queue.
 */
static inline struct fc_frame *fc_fcp_frame_alloc(struct fc_lport *lport,
						  size_t len)
{
	struct fc_frame *fp;
	unsigned long flags;

	fp = fc_frame_alloc(lport, len);
	if (likely(fp))
		return fp;

	/* error case */
	spin_lock_irqsave(lport->host->host_lock, flags);
	fc_fcp_can_queue_ramp_down(lport);
	spin_unlock_irqrestore(lport->host->host_lock, flags);
	return NULL;
}

/**
 * fc_fcp_recv_data() - Handler for receiving SCSI-FCP data from a target
 * @fsp: The FCP packet the data is on
 * @fp:	 The data frame
 */
static void fc_fcp_recv_data(struct fc_fcp_pkt *fsp, struct fc_frame *fp)
{
	struct scsi_cmnd *sc = fsp->cmd;
	struct fc_lport *lport = fsp->lp;
	struct fcoe_dev_stats *stats;
	struct fc_frame_header *fh;
	size_t start_offset;
	size_t offset;
	u32 crc;
	u32 copy_len = 0;
	size_t len;
	void *buf;
	struct scatterlist *sg;
	u32 nents;
	u8 host_bcode = FC_COMPLETE;

	fh = fc_frame_header_get(fp);
	offset = ntohl(fh->fh_parm_offset);
	start_offset = offset;
	len = fr_len(fp) - sizeof(*fh);
	buf = fc_frame_payload_get(fp, 0);
<commit_msg>[SCSI] libfc: Move host_lock usage into ramp_up/down routines<commit_after>/*
 * Copyright(c) 2007 Intel Corporation. All rights reserved.
 * Copyright(c) 2008 Red Hat, Inc.  All rights reserved.
 * Copyright(c) 2008 <NAME>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope 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.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Maintained at www.Open-FCoE.org
 */

#include <linux/module.h>
#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/spinlock.h>
#include <linux/scatterlist.h>
#include <linux/err.h>
#include <linux/crc32.h>
#include <linux/slab.h>

#include <scsi/scsi_tcq.h>
#include <scsi/scsi.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_cmnd.h>

#include <scsi/fc/fc_fc2.h>

#include <scsi/libfc.h>
#include <scsi/fc_encode.h>

#include "fc_libfc.h"

static struct kmem_cache *scsi_pkt_cachep;

/* SRB state definitions */
#define FC_SRB_FREE		0		/* cmd is free */
#define FC_SRB_CMD_SENT		(1 << 0)	/* cmd has been sent */
#define FC_SRB_RCV_STATUS	(1 << 1)	/* response has arrived */
#define FC_SRB_ABORT_PENDING	(1 << 2)	/* cmd abort sent to device */
#define FC_SRB_ABORTED		(1 << 3)	/* abort acknowledged */
#define FC_SRB_DISCONTIG	(1 << 4)	/* non-sequential data recvd */
#define FC_SRB_COMPL		(1 << 5)	/* fc_io_compl has been run */
#define FC_SRB_FCP_PROCESSING_TMO (1 << 6)	/* timer function processing */

#define FC_SRB_READ		(1 << 1)
#define FC_SRB_WRITE		(1 << 0)

/* constant added to e_d_tov timeout to get rec_tov value */
#define REC_TOV_CONST		1

/*
 * The SCp.ptr should be tested and set under the scsi_pkt_queue lock
 */
#define CMD_SP(Cmnd)		    ((struct fc_fcp_pkt *)(Cmnd)->SCp.ptr)
#define CMD_ENTRY_STATUS(Cmnd)	    ((Cmnd)->SCp.have_data_in)
#define CMD_COMPL_STATUS(Cmnd)	    ((Cmnd)->SCp.this_residual)
#define CMD_SCSI_STATUS(Cmnd)	    ((Cmnd)->SCp.Status)
#define CMD_RESID_LEN(Cmnd)	    ((Cmnd)->SCp.buffers_residual)

/**
 * struct fc_fcp_internal - FCP layer internal data
 * @scsi_pkt_pool: Memory pool to draw FCP packets from
 * @scsi_queue_lock: Protects the scsi_pkt_queue
 * @scsi_pkt_queue: Current FCP packets
 * @last_can_queue_ramp_down_time: ramp down time
 * @last_can_queue_ramp_up_time: ramp up time
 * @max_can_queue: max can_queue size
 */
struct fc_fcp_internal {
	mempool_t		*scsi_pkt_pool;
	spinlock_t		scsi_queue_lock;
	struct list_head	scsi_pkt_queue;
	unsigned long		last_can_queue_ramp_down_time;
	unsigned long		last_can_queue_ramp_up_time;
	int			max_can_queue;
};

#define fc_get_scsi_internal(x)	((struct fc_fcp_internal *)(x)->scsi_priv)

/*
 * function prototypes
 * FC scsi I/O related functions
 */
static void fc_fcp_recv_data(struct fc_fcp_pkt *, struct fc_frame *);
static void fc_fcp_recv(struct fc_seq *, struct fc_frame *, void *);
static void fc_fcp_resp(struct fc_fcp_pkt *, struct fc_frame *);
static void fc_fcp_complete_locked(struct fc_fcp_pkt *);
static void fc_tm_done(struct fc_seq *, struct fc_frame *, void *);
static void fc_fcp_error(struct fc_fcp_pkt *, struct fc_frame *);
static void fc_fcp_recovery(struct fc_fcp_pkt *, u8 code);
static void fc_fcp_timeout(unsigned long);
static void fc_fcp_rec(struct fc_fcp_pkt *);
static void fc_fcp_rec_error(struct fc_fcp_pkt *, struct fc_frame *);
static void fc_fcp_rec_resp(struct fc_seq *, struct fc_frame *, void *);
static void fc_io_compl(struct fc_fcp_pkt *);

static void fc_fcp_srr(struct fc_fcp_pkt *, enum fc_rctl, u32);
static void fc_fcp_srr_resp(struct fc_seq *, struct fc_frame *, void *);
static void fc_fcp_srr_error(struct fc_fcp_pkt *, struct fc_frame *);

/*
 * command status codes
 */
#define FC_COMPLETE		0
#define FC_CMD_ABORTED		1
#define FC_CMD_RESET		2
#define FC_CMD_PLOGO		3
#define FC_SNS_RCV		4
#define FC_TRANS_ERR		5
#define FC_DATA_OVRRUN		6
#define FC_DATA_UNDRUN		7
#define FC_ERROR		8
#define FC_HRD_ERROR		9
#define FC_CRC_ERROR		10
#define FC_TIMED_OUT		11

/*
 * Error recovery timeout values.
 */
#define FC_SCSI_TM_TOV		(10 * HZ)
#define FC_HOST_RESET_TIMEOUT	(30 * HZ)
#define FC_CAN_QUEUE_PERIOD	(60 * HZ)

#define FC_MAX_ERROR_CNT	5
#define FC_MAX_RECOV_RETRY	3

#define FC_FCP_DFLT_QUEUE_DEPTH 32

/**
 * fc_fcp_pkt_alloc() - Allocate a fcp_pkt
 * @lport: The local port that the FCP packet is for
 * @gfp:   GFP flags for allocation
 *
 * Return value: fcp_pkt structure or null on allocation failure.
 * Context:	 Can be called from process context, no lock is required.
 */
static struct fc_fcp_pkt *fc_fcp_pkt_alloc(struct fc_lport *lport, gfp_t gfp)
{
	struct fc_fcp_internal *si = fc_get_scsi_internal(lport);
	struct fc_fcp_pkt *fsp;

	fsp = mempool_alloc(si->scsi_pkt_pool, gfp);
	if (fsp) {
		memset(fsp, 0, sizeof(*fsp));
		fsp->lp = lport;
		fsp->xfer_ddp = FC_XID_UNKNOWN;
		atomic_set(&fsp->ref_cnt, 1);
		init_timer(&fsp->timer);
		INIT_LIST_HEAD(&fsp->list);
		spin_lock_init(&fsp->scsi_pkt_lock);
	}
	return fsp;
}

/**
 * fc_fcp_pkt_release() - Release hold on a fcp_pkt
 * @fsp: The FCP packet to be released
 *
 * Context: Can be called from process or interrupt context,
 *	    no lock is required.
 */
static void fc_fcp_pkt_release(struct fc_fcp_pkt *fsp)
{
	if (atomic_dec_and_test(&fsp->ref_cnt)) {
		struct fc_fcp_internal *si = fc_get_scsi_internal(fsp->lp);

		mempool_free(fsp, si->scsi_pkt_pool);
	}
}

/**
 * fc_fcp_pkt_hold() - Hold a fcp_pkt
 * @fsp: The FCP packet to be held
 */
static void fc_fcp_pkt_hold(struct fc_fcp_pkt *fsp)
{
	atomic_inc(&fsp->ref_cnt);
}

/**
 * fc_fcp_pkt_destory() - Release hold on a fcp_pkt
 * @seq: The sequence that the FCP packet is on (required by destructor API)
 * @fsp: The FCP packet to be released
 *
 * This routine is called by a destructor callback in the exch_seq_send()
 * routine of the libfc Transport Template. The 'struct fc_seq' is a required
 * argument even though it is not used by this routine.
 *
 * Context: No locking required.
 */
static void fc_fcp_pkt_destroy(struct fc_seq *seq, void *fsp)
{
	fc_fcp_pkt_release(fsp);
}

/**
 * fc_fcp_lock_pkt() - Lock a fcp_pkt and increase its reference count
 * @fsp: The FCP packet to be locked and incremented
 *
 * We should only return error if we return a command to SCSI-ml before
 * getting a response. This can happen in cases where we send a abort, but
 * do not wait for the response and the abort and command can be passing
 * each other on the wire/network-layer.
 *
 * Note: this function locks the packet and gets a reference to allow
 * callers to call the completion function while the lock is held and
 * not have to worry about the packets refcount.
 *
 * TODO: Maybe we should just have callers grab/release the lock and
 * have a function that they call to verify the fsp and grab a ref if
 * needed.
 */
static inline int fc_fcp_lock_pkt(struct fc_fcp_pkt *fsp)
{
	spin_lock_bh(&fsp->scsi_pkt_lock);
	if (fsp->state & FC_SRB_COMPL) {
		spin_unlock_bh(&fsp->scsi_pkt_lock);
		return -EPERM;
	}

	fc_fcp_pkt_hold(fsp);
	return 0;
}

/**
 * fc_fcp_unlock_pkt() - Release a fcp_pkt's lock and decrement its
 *			 reference count
 * @fsp: The FCP packet to be unlocked and decremented
 */
static inline void fc_fcp_unlock_pkt(struct fc_fcp_pkt *fsp)
{
	spin_unlock_bh(&fsp->scsi_pkt_lock);
	fc_fcp_pkt_release(fsp);
}

/**
 * fc_fcp_timer_set() - Start a timer for a fcp_pkt
 * @fsp:   The FCP packet to start a timer for
 * @delay: The timeout period for the timer
 */
static void fc_fcp_timer_set(struct fc_fcp_pkt *fsp, unsigned long delay)
{
	if (!(fsp->state & FC_SRB_COMPL))
		mod_timer(&fsp->timer, jiffies + delay);
}

/**
 * fc_fcp_send_abort() - Send an abort for exchanges associated with a
 *			 fcp_pkt
 * @fsp: The FCP packet to abort exchanges on
 */
static int fc_fcp_send_abort(struct fc_fcp_pkt *fsp)
{
	if (!fsp->seq_ptr)
		return -EINVAL;

	fsp->state |= FC_SRB_ABORT_PENDING;
	return fsp->lp->tt.seq_exch_abort(fsp->seq_ptr, 0);
}

/**
 * fc_fcp_retry_cmd() - Retry a fcp_pkt
 * @fsp: The FCP packet to be retried
 *
 * Sets the status code to be FC_ERROR and then calls
 * fc_fcp_complete_locked() which in turn calls fc_io_compl().
 * fc_io_compl() will notify the SCSI-ml that the I/O is done.
 * The SCSI-ml will retry the command.
 */
static void fc_fcp_retry_cmd(struct fc_fcp_pkt *fsp)
{
	if (fsp->seq_ptr) {
		fsp->lp->tt.exch_done(fsp->seq_ptr);
		fsp->seq_ptr = NULL;
	}

	fsp->state &= ~FC_SRB_ABORT_PENDING;
	fsp->io_status = 0;
	fsp->status_code = FC_ERROR;
	fc_fcp_complete_locked(fsp);
}

/**
 * fc_fcp_ddp_setup() - Calls a LLD's ddp_setup routine to set up DDP context
 * @fsp: The FCP packet that will manage the DDP frames
 * @xid: The XID that will be used for the DDP exchange
 */
void fc_fcp_ddp_setup(struct fc_fcp_pkt *fsp, u16 xid)
{
	struct fc_lport *lport;

	lport = fsp->lp;
	if ((fsp->req_flags & FC_SRB_READ) &&
	    (lport->lro_enabled) && (lport->tt.ddp_setup)) {
		if (lport->tt.ddp_setup(lport, xid, scsi_sglist(fsp->cmd),
					scsi_sg_count(fsp->cmd)))
			fsp->xfer_ddp = xid;
	}
}

/**
 * fc_fcp_ddp_done() - Calls a LLD's ddp_done routine to release any
 *		       DDP related resources for a fcp_pkt
 * @fsp: The FCP packet that DDP had been used on
 */
static void fc_fcp_ddp_done(struct fc_fcp_pkt *fsp)
{
	struct fc_lport *lport;

	if (!fsp)
		return;

	if (fsp->xfer_ddp == FC_XID_UNKNOWN)
		return;

	lport = fsp->lp;
	if (lport->tt.ddp_done) {
		fsp->xfer_len = lport->tt.ddp_done(lport, fsp->xfer_ddp);
		fsp->xfer_ddp = FC_XID_UNKNOWN;
	}
}

/**
 * fc_fcp_can_queue_ramp_up() - increases can_queue
 * @lport: lport to ramp up can_queue
 */
static void fc_fcp_can_queue_ramp_up(struct fc_lport *lport)
{
	struct fc_fcp_internal *si = fc_get_scsi_internal(lport);
	unsigned long flags;
	int can_queue;

	spin_lock_irqsave(lport->host->host_lock, flags);

	if (si->last_can_queue_ramp_up_time &&
	    (time_before(jiffies, si->last_can_queue_ramp_up_time +
			 FC_CAN_QUEUE_PERIOD)))
		goto unlock;

	if (time_before(jiffies, si->last_can_queue_ramp_down_time +
			FC_CAN_QUEUE_PERIOD))
		goto unlock;

	si->last_can_queue_ramp_up_time = jiffies;

	can_queue = lport->host->can_queue << 1;
	if (can_queue >= si->max_can_queue) {
		can_queue = si->max_can_queue;
		si->last_can_queue_ramp_down_time = 0;
	}
	lport->host->can_queue = can_queue;
	shost_printk(KERN_ERR, lport->host, "libfc: increased "
		     "can_queue to %d.\n", can_queue);

unlock:
	spin_unlock_irqrestore(lport->host->host_lock, flags);
}

/**
 * fc_fcp_can_queue_ramp_down() - reduces can_queue
 * @lport: lport to reduce can_queue
 *
 * If we are getting memory allocation failures, then we may
 * be trying to execute too many commands. We let the running
 * commands complete or timeout, then try again with a reduced
 * can_queue. Eventually we will hit the point where we run
 * on all reserved structs.
 */
static void fc_fcp_can_queue_ramp_down(struct fc_lport *lport)
{
	struct fc_fcp_internal *si = fc_get_scsi_internal(lport);
	unsigned long flags;
	int can_queue;

	spin_lock_irqsave(lport->host->host_lock, flags);

	if (si->last_can_queue_ramp_down_time &&
	    (time_before(jiffies, si->last_can_queue_ramp_down_time +
			 FC_CAN_QUEUE_PERIOD)))
		goto unlock;

	si->last_can_queue_ramp_down_time = jiffies;

	can_queue = lport->host->can_queue;
	can_queue >>= 1;
	if (!can_queue)
		can_queue = 1;
	lport->host->can_queue = can_queue;
	shost_printk(KERN_ERR, lport->host, "libfc: Could not allocate frame.\n"
		     "Reducing can_queue to %d.\n", can_queue);

unlock:
	spin_unlock_irqrestore(lport->host->host_lock, flags);
}

/*
 * fc_fcp_frame_alloc() -  Allocates fc_frame structure and buffer.
 * @lport:	fc lport struct
 * @len:	payload length
 *
 * Allocates fc_frame structure and buffer but if fails to allocate
 * then reduce can_queue.
 */
static inline struct fc_frame *fc_fcp_frame_alloc(struct fc_lport *lport,
						  size_t len)
{
	struct fc_frame *fp;

	fp = fc_frame_alloc(lport, len);
	if (likely(fp))
		return fp;

	/* error case */
	fc_fcp_can_queue_ramp_down(lport);
	return NULL;
}

/**
 * fc_fcp_recv_data() - Handler for receiving SCSI-FCP data from a target
 * @fsp: The FCP packet the data is on
 * @fp:	 The data frame
 */
static void fc_fcp_recv_data(struct fc_fcp_pkt *fsp, struct fc_frame *fp)
{
	struct scsi_cmnd *sc = fsp->cmd;
	struct fc_lport *lport = fsp->lp;
	struct fcoe_dev_stats *stats;
	struct fc_frame_header *fh;
	size_t start_offset;
	size_t offset;
	u32 crc;
	u32 copy_len = 0;
	size_t len;
	void *buf;
	struct scatterlist *sg;
	u32 nents;
	u8 host_bcode = FC_COMPLETE;

	fh = fc_frame_header_get(fp);
	offset = ntohl(fh->fh_parm_offset);
	start_offset = offset;
	len = fr_len(fp) - sizeof(*fh);
	buf = fc_frame_payload_get(fp, 0);

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