[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/include/scsi/libfc.h b/include/scsi/libfc.h
index 042f4ade..b9e6c1c 100644
--- a/include/scsi/libfc.h
+++ b/include/scsi/libfc.h
@@ -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 @@
/* Operational Information */
struct libfc_function_template tt;
- u16 link_status;
+ u8 link_up;
+ u8 qfull;
enum fc_lport_state state;
unsigned long boot_time;
@@ -704,12 +702,6 @@
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.
*/
int fc_lport_config(struct fc_lport *);