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Commit bc0e17f6 authored by Vasu Dev's avatar Vasu Dev Committed by James Bottomley
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[SCSI] libfc, fcoe: fixed locking issues with lport->lp_mutex around lport->link_status 



The fcoe_xmit could call fc_pause in case the pending skb queue len is larger
than FCOE_MAX_QUEUE_DEPTH, the fc_pause was trying to grab lport->lp_muex to
change lport->link_status and that had these issues :-

1. The fcoe_xmit was getting called with bh disabled, thus causing
"BUG: scheduling while atomic" when grabbing lport->lp_muex with bh disabled.

2. fc_linkup and fc_linkdown function calls lport_enter function with
lport->lp_mutex held and these enter function in turn calls fcoe_xmit to send
lport related FC frame, e.g. fc_linkup => fc_lport_enter_flogi to send flogi
req. In this case grabbing the same lport->lp_mutex again in fc_puase from
fcoe_xmit would cause deadlock.

The lport->lp_mutex was used for setting FC_PAUSE in fcoe_xmit path but
FC_PAUSE bit was not used anywhere beside just setting and clear this
bit in lport->link_status, instead used a separate field qfull in fc_lport
to eliminate need for lport->lp_mutex to track pending queue full condition
and in turn avoid above described two locking issues.

Also added check for lp->qfull in fc_fcp_lport_queue_ready to trigger
SCSI_MLQUEUE_HOST_BUSY when lp->qfull is set to prevent more scsi-ml cmds
while lp->qfull is set.

This patch eliminated FC_LINK_UP and FC_PAUSE and instead used dedicated
fields in fc_lport for this, this simplified all related conditional
code.

Also removed fc_pause and fc_unpause functions and instead used newly added
lport->qfull directly in fcoe.

Signed-off-by: default avatarVasu Dev <vasu.dev@intel.com>
Signed-off-by: default avatarRobert Love <robert.w.love@intel.com>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@HansenPartnership.com>
parent a7e84f2b

drivers/scsi/fcoe/fcoe_sw.c

+3 −3
Original line number Diff line number Diff line
@@ -116,7 +116,8 @@ static int fcoe_sw_lport_config(struct fc_lport *lp) 
{

	int i = 0;



	lp->link_status = 0;

	lp->link_up = 0;

	lp->qfull = 0;

	lp->max_retry_count = 3;

	lp->e_d_tov = 2 * 1000;	/* FC-FS default */

	lp->r_a_tov = 2 * 2 * 1000;
@@ -181,9 +182,8 @@ static int fcoe_sw_netdev_config(struct fc_lport *lp, struct net_device *netdev) 
	if (fc_set_mfs(lp, mfs))

		return -EINVAL;



	lp->link_status = ~FC_PAUSE & ~FC_LINK_UP;

	if (!fcoe_link_ok(lp))

		lp->link_status |= FC_LINK_UP;

		lp->link_up = 1;



	/* offload features support */

	if (fc->real_dev->features & NETIF_F_SG)

drivers/scsi/fcoe/libfcoe.c

+17 −24
Original line number Diff line number Diff line
@@ -504,7 +504,7 @@ int fcoe_xmit(struct fc_lport *lp, struct fc_frame *fp) 
	if (rc) {

		fcoe_insert_wait_queue(lp, skb);

		if (fc->fcoe_pending_queue.qlen > FCOE_MAX_QUEUE_DEPTH)

			fc_pause(lp);

			lp->qfull = 1;

	}



	return 0;
@@ -718,7 +718,7 @@ static void fcoe_recv_flogi(struct fcoe_softc *fc, struct fc_frame *fp, u8 *sa) 
 * fcoe_watchdog - fcoe timer callback

 * @vp:

 *

 * This checks the pending queue length for fcoe and put fcoe to be paused state

 * This checks the pending queue length for fcoe and set lport qfull

 * if the FCOE_MAX_QUEUE_DEPTH is reached. This is done for all fc_lport on the

 * fcoe_hostlist.

 *
@@ -728,17 +728,17 @@ void fcoe_watchdog(ulong vp) 
{

	struct fc_lport *lp;

	struct fcoe_softc *fc;

	int paused = 0;

	int qfilled = 0;



	read_lock(&fcoe_hostlist_lock);

	list_for_each_entry(fc, &fcoe_hostlist, list) {

		lp = fc->lp;

		if (lp) {

			if (fc->fcoe_pending_queue.qlen > FCOE_MAX_QUEUE_DEPTH)

				paused = 1;

				qfilled = 1;

			if (fcoe_check_wait_queue(lp) <	 FCOE_MAX_QUEUE_DEPTH) {

				if (paused)

					fc_unpause(lp);

				if (qfilled)

					lp->qfull = 0;

			}

		}

	}
@@ -767,8 +767,7 @@ void fcoe_watchdog(ulong vp) 
 **/

static int fcoe_check_wait_queue(struct fc_lport *lp)

{

	int rc, unpause = 0;

	int paused = 0;

	int rc;

	struct sk_buff *skb;

	struct fcoe_softc *fc;
@@ -776,10 +775,10 @@ static int fcoe_check_wait_queue(struct fc_lport *lp) 
	spin_lock_bh(&fc->fcoe_pending_queue.lock);



	/*

	 * is this interface paused?

	 * if interface pending queue full then set qfull in lport.

	 */

	if (fc->fcoe_pending_queue.qlen > FCOE_MAX_QUEUE_DEPTH)

		paused = 1;

		lp->qfull = 1;

	if (fc->fcoe_pending_queue.qlen) {

		while ((skb = __skb_dequeue(&fc->fcoe_pending_queue)) != NULL) {

			spin_unlock_bh(&fc->fcoe_pending_queue.lock);
@@ -791,11 +790,9 @@ static int fcoe_check_wait_queue(struct fc_lport *lp) 
			spin_lock_bh(&fc->fcoe_pending_queue.lock);

		}

		if (fc->fcoe_pending_queue.qlen < FCOE_MAX_QUEUE_DEPTH)

			unpause = 1;

			lp->qfull = 0;

	}

	spin_unlock_bh(&fc->fcoe_pending_queue.lock);

	if ((unpause) && (paused))

		fc_unpause(lp);

	return fc->fcoe_pending_queue.qlen;

}
@@ -873,7 +870,7 @@ static int fcoe_device_notification(struct notifier_block *notifier, 
	struct net_device *real_dev = ptr;

	struct fcoe_softc *fc;

	struct fcoe_dev_stats *stats;

	u16 new_status;

	u32 new_link_up;

	u32 mfs;

	int rc = NOTIFY_OK;
@@ -890,17 +887,15 @@ static int fcoe_device_notification(struct notifier_block *notifier, 
		goto out;

	}



	new_status = lp->link_status;

	new_link_up = lp->link_up;

	switch (event) {

	case NETDEV_DOWN:

	case NETDEV_GOING_DOWN:

		new_status &= ~FC_LINK_UP;

		new_link_up = 0;

		break;

	case NETDEV_UP:

	case NETDEV_CHANGE:

		new_status &= ~FC_LINK_UP;

		if (!fcoe_link_ok(lp))

			new_status |= FC_LINK_UP;

		new_link_up = !fcoe_link_ok(lp);

		break;

	case NETDEV_CHANGEMTU:

		mfs = fc->real_dev->mtu -
@@ -908,17 +903,15 @@ static int fcoe_device_notification(struct notifier_block *notifier, 
			 sizeof(struct fcoe_crc_eof));

		if (mfs >= FC_MIN_MAX_FRAME)

			fc_set_mfs(lp, mfs);

		new_status &= ~FC_LINK_UP;

		if (!fcoe_link_ok(lp))

			new_status |= FC_LINK_UP;

		new_link_up = !fcoe_link_ok(lp);

		break;

	case NETDEV_REGISTER:

		break;

	default:

		FC_DBG("unknown event %ld call", event);

	}

	if (lp->link_status != new_status) {

		if ((new_status & FC_LINK_UP) == FC_LINK_UP)

	if (lp->link_up != new_link_up) {

		if (new_link_up)

			fc_linkup(lp);

		else {

			stats = lp->dev_stats[smp_processor_id()];

drivers/scsi/libfc/fc_fcp.c

+2 −2
Original line number Diff line number Diff line
@@ -1621,7 +1621,7 @@ static void fc_fcp_srr_error(struct fc_fcp_pkt *fsp, struct fc_frame *fp) 
static inline int fc_fcp_lport_queue_ready(struct fc_lport *lp)

{

	/* lock ? */

	return (lp->state == LPORT_ST_READY) && (lp->link_status & FC_LINK_UP);

	return (lp->state == LPORT_ST_READY) && lp->link_up && !lp->qfull;

}



/**
@@ -1890,7 +1890,7 @@ int fc_eh_abort(struct scsi_cmnd *sc_cmd) 
	lp = shost_priv(sc_cmd->device->host);

	if (lp->state != LPORT_ST_READY)

		return rc;

	else if (!(lp->link_status & FC_LINK_UP))

	else if (!lp->link_up)

		return rc;



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

drivers/scsi/libfc/fc_lport.c

+6 −30
Original line number Diff line number Diff line
@@ -250,7 +250,7 @@ void fc_get_host_port_state(struct Scsi_Host *shost) 
{

	struct fc_lport *lp = shost_priv(shost);



	if ((lp->link_status & FC_LINK_UP) == FC_LINK_UP)

	if (lp->link_up)

		fc_host_port_state(shost) = FC_PORTSTATE_ONLINE;

	else

		fc_host_port_state(shost) = FC_PORTSTATE_OFFLINE;
@@ -577,8 +577,8 @@ void fc_linkup(struct fc_lport *lport) 
		       fc_host_port_id(lport->host));



	mutex_lock(&lport->lp_mutex);

	if ((lport->link_status & FC_LINK_UP) != FC_LINK_UP) {

		lport->link_status |= FC_LINK_UP;

	if (!lport->link_up) {

		lport->link_up = 1;



		if (lport->state == LPORT_ST_RESET)

			fc_lport_enter_flogi(lport);
@@ -597,8 +597,8 @@ void fc_linkdown(struct fc_lport *lport) 
	FC_DEBUG_LPORT("Link is down for port (%6x)\n",

		       fc_host_port_id(lport->host));



	if ((lport->link_status & FC_LINK_UP) == FC_LINK_UP) {

		lport->link_status &= ~(FC_LINK_UP);

	if (lport->link_up) {

		lport->link_up = 0;

		fc_lport_enter_reset(lport);

		lport->tt.fcp_cleanup(lport);

	}
@@ -606,30 +606,6 @@ void fc_linkdown(struct fc_lport *lport) 
}

EXPORT_SYMBOL(fc_linkdown);



/**

 * fc_pause - Pause the flow of frames

 * @lport: The lport to be paused

 */

void fc_pause(struct fc_lport *lport)

{

	mutex_lock(&lport->lp_mutex);

	lport->link_status |= FC_PAUSE;

	mutex_unlock(&lport->lp_mutex);

}

EXPORT_SYMBOL(fc_pause);



/**

 * fc_unpause - Unpause the flow of frames

 * @lport: The lport to be unpaused

 */

void fc_unpause(struct fc_lport *lport)

{

	mutex_lock(&lport->lp_mutex);

	lport->link_status &= ~(FC_PAUSE);

	mutex_unlock(&lport->lp_mutex);

}

EXPORT_SYMBOL(fc_unpause);



/**

 * fc_fabric_logoff - Logout of the fabric

 * @lport:	      fc_lport pointer to logoff the fabric
@@ -977,7 +953,7 @@ static void fc_lport_enter_reset(struct fc_lport *lport) 
	fc_host_fabric_name(lport->host) = 0;

	fc_host_port_id(lport->host) = 0;



	if ((lport->link_status & FC_LINK_UP) == FC_LINK_UP)

	if (lport->link_up)

		fc_lport_enter_flogi(lport);

}

include/scsi/libfc.h

+2 −10
Original line number Diff line number Diff line
@@ -68,9 +68,6 @@ 
/*

 * FC HBA status

 */

#define FC_PAUSE		    (1 << 1)

#define FC_LINK_UP		    (1 << 0)



enum fc_lport_state {

	LPORT_ST_NONE = 0,

	LPORT_ST_FLOGI,
@@ -603,7 +600,8 @@ struct fc_lport { 


	/* Operational Information */

	struct libfc_function_template tt;

	u16			link_status;

	u8			link_up;

	u8			qfull;

	enum fc_lport_state	state;

	unsigned long		boot_time;
@@ -703,12 +701,6 @@ void fc_linkup(struct fc_lport *); 
 */

void fc_linkdown(struct fc_lport *);



/*

 * Pause and unpause traffic.

 */

void fc_pause(struct fc_lport *);

void fc_unpause(struct fc_lport *);



/*

 * Configure the local port.

 */