From: Marcus Barrow <mbarrow@redhat.com>
Date: Wed, 19 Mar 2008 23:00:24 -0400
Subject: [net] qla3xxx: have link SM use work threads
Message-id: 20080320030024.7649.88517.sendpatchset@shell.boston.redhat.com
O-Subject: [rhel 5.2 bug] qla3xxx - Move link state machine from timer thread to kernel thread to avoid CPU lockup.
Bugzilla: 409171

BZ 409171 qla3xxx - Move link state machine from timer thread to kernel thread to avoid CPU lockup

This problem can cause a panic from nmi watchdog.

The link state machine requires access to some resources that
are shared with the iSCSI function on the chip.  (See iSCSI
driver at drivers/scsi/qla4xxx)  If the interface is being
up/downed at a rapid pace this driver may need to sleep
waiting to get access to the common resources. For this we
are moving the state machine to run as a work thread.

Applies cleanly to 2.6.18-84.el5.  Tested at QLogic.

Acked-by: Alan Cox <alan@redhat.com>

diff --git a/drivers/net/qla3xxx.c b/drivers/net/qla3xxx.c
index 1600945..935f027 100644
--- a/drivers/net/qla3xxx.c
+++ b/drivers/net/qla3xxx.c
@@ -39,7 +39,7 @@
 
 #define DRV_NAME  	"qla3xxx"
 #define DRV_STRING 	"QLogic ISP3XXX Network Driver"
-#define DRV_VERSION	"v2.03.00-k4-RHEL5U2"
+#define DRV_VERSION	"v2.03.00-k4-RHEL5.2-01"
 #define PFX		DRV_NAME " "
 
 static const char ql3xxx_driver_name[] = DRV_NAME;
@@ -1657,7 +1657,7 @@ static int ql_finish_auto_neg(struct ql3_adapter *qdev)
 	return 0;
 }
 
-static void ql_link_state_machine(struct ql3_adapter *qdev)
+static void ql_link_state_machine_work(struct ql3_adapter *qdev)
 {
 	u32 curr_link_state;
 	unsigned long hw_flags;
@@ -1673,6 +1673,8 @@ static void ql_link_state_machine(struct ql3_adapter *qdev)
 			       "state.\n", qdev->ndev->name);
 
 		spin_unlock_irqrestore(&qdev->hw_lock, hw_flags);		
+		/* Restart timer on 1 second interval. */
+		mod_timer(&qdev->adapter_timer, jiffies + HZ * 1);\
 		return;
 	}
 
@@ -1717,6 +1719,8 @@ static void ql_link_state_machine(struct ql3_adapter *qdev)
 		break;
 	}
 	spin_unlock_irqrestore(&qdev->hw_lock, hw_flags);
+	/* Restart timer on 1 second interval. */
+	mod_timer(&qdev->adapter_timer, jiffies + HZ * 1);
 }
 
 /*
@@ -3977,20 +3981,7 @@ static void ql_get_board_info(struct ql3_adapter *qdev)
 static void ql3xxx_timer(unsigned long ptr)
 {
 	struct ql3_adapter *qdev = (struct ql3_adapter *)ptr;
-
-	if (test_bit(QL_RESET_ACTIVE,&qdev->flags)) {
-		printk(KERN_DEBUG PFX
-		       "%s: Reset in progress.\n",
-		       qdev->ndev->name);
-		goto end;
-	}
-
-	if (test_bit(QL_ADAPTER_UP,&qdev->flags))
-		ql_link_state_machine(qdev);
-
-	/* Restart timer on 2 second interval. */
-end:
-	mod_timer(&qdev->adapter_timer, jiffies + HZ * 1);
+	queue_work(qdev->workqueue, &qdev->link_state_work);
 }
 
 static int __devinit ql3xxx_probe(struct pci_dev *pdev,
@@ -4144,6 +4135,8 @@ static int __devinit ql3xxx_probe(struct pci_dev *pdev,
 	INIT_WORK(&qdev->reset_work, (void (*)(void *))ql_reset_work, qdev);
 	INIT_WORK(&qdev->tx_timeout_work,
 		  (void (*)(void *))ql_tx_timeout_work, qdev);
+	INIT_WORK(&qdev->link_state_work, 
+		(void (*)(void *))ql_link_state_machine_work,qdev);
 
 	init_timer(&qdev->adapter_timer);
 	qdev->adapter_timer.function = ql3xxx_timer;
diff --git a/drivers/net/qla3xxx.h b/drivers/net/qla3xxx.h
index f66466d..8f0c6eb 100644
--- a/drivers/net/qla3xxx.h
+++ b/drivers/net/qla3xxx.h
@@ -1285,6 +1285,7 @@ struct ql3_adapter {
 	struct workqueue_struct *workqueue;
 	struct work_struct reset_work;
 	struct work_struct tx_timeout_work;
+	struct work_struct link_state_work;
 	u32 max_frame_size;
 	u32 device_id;
 	u16 phyType;