[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>
diff --git a/drivers/scsi/libfc/fc_lport.c b/drivers/scsi/libfc/fc_lport.c
index 5db223c..a6ab692 100644
--- a/drivers/scsi/libfc/fc_lport.c
+++ b/drivers/scsi/libfc/fc_lport.c
@@ -250,7 +250,7 @@
{
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 @@
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 @@
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);
}
@@ -607,30 +607,6 @@
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 @@
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);
}