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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: Vasu Dev <vasu.dev@intel.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
This commit is contained in:
Vasu Dev 2009-02-27 10:54:57 -08:00 committed by James Bottomley
parent a7e84f2b83
commit bc0e17f691
5 changed files with 30 additions and 69 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
drivers/scsi/fcoe/fcoe_sw.c
View File

@ -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)

41
drivers/scsi/fcoe/libfcoe.c
View File

@ -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()];

4
drivers/scsi/libfc/fc_fcp.c
View File

@ -1621,7 +1621,7 @@ out:
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);

36
drivers/scsi/libfc/fc_lport.c
View File

@ -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);
}

12
include/scsi/libfc.h
View File

@ -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.
*/