From: Michal Schmidt <mschmidt@redhat.com>
Date: Mon, 29 Nov 2010 17:33:15 -0500
Subject: [net] bnx2x: force interrupt mode for iscsi unset mac
Message-id: <20101129183315.4a6b2db3@brian.englab.brq.redhat.com>
Patchwork-id: 29659
O-Subject: [RHEL5.6 PATCH v2] bnx2x: force interrupt mode for iscsi unset mac
Bugzilla: 655885
RH-Acked-by: Stefan Assmann <sassmann@redhat.com>
RH-Acked-by: David S. Miller <davem@redhat.com>

BZ: https://bugzilla.redhat.com/show_bug.cgi?id=655885

This fixes a race condition resulting in kernel panic.
bnx2x_wait_ramrod() when called from bnx2x_unregister_cnic() could
touch the RX rings while NAPI was processing them at the same time.
The bug can be reproduced by loading/unloading the cnic module while rx
traffic is going on.

The patch adds an additional argument "force_int" to the function. When
set, the function is forced to wait using an interrupt, instead of
polling the bnx2x fastpath directly, thus preventing the collision with
NAPI.

Brew build: https://brewweb.devel.redhat.com/taskinfo?taskID=2919358

Tested by me on hp-bl495cg5-01.rhts.bos.redhat.com.

Upstream status:
Fixed in upstream since commit 523224a3b3cd407ce4e6731a087194e13a90db18:
  Author: Dmitry Kravkov <dmitry@broadcom.com>
  Date:   Wed Oct 6 03:23:26 2010 +0000

      bnx2x, cnic, bnx2i: use new FW/HSI

This is a different, minimal fix.
Patch by Dmitry Kravkov.

[v1->v2: only added a comment for the force_int argument (suggested by
Dean Nelson)]

Thanks,
Michal

diff --git a/drivers/net/bnx2x/bnx2x_cmn.c b/drivers/net/bnx2x/bnx2x_cmn.c
index ae21df8..93c55a1 100644
--- a/drivers/net/bnx2x/bnx2x_cmn.c
+++ b/drivers/net/bnx2x/bnx2x_cmn.c
@@ -1414,7 +1414,7 @@ int bnx2x_nic_load(struct bnx2x *bp, int load_mode)
 		/* Set iSCSI L2 MAC */
 		mutex_lock(&bp->cnic_mutex);
 		if (bp->cnic_eth_dev.drv_state & CNIC_DRV_STATE_REGD) {
-			bnx2x_set_iscsi_eth_mac_addr(bp, 1);
+			bnx2x_set_iscsi_eth_mac_addr(bp, 1, 0);
 			bp->cnic_flags |= BNX2X_CNIC_FLAG_MAC_SET;
 			bnx2x_init_sb(bp, bp->cnic_sb, bp->cnic_sb_mapping,
 				      CNIC_SB_ID(bp));
diff --git a/drivers/net/bnx2x/bnx2x_cmn.h b/drivers/net/bnx2x/bnx2x_cmn.h
index 2e75df7..f5ee274 100644
--- a/drivers/net/bnx2x/bnx2x_cmn.h
+++ b/drivers/net/bnx2x/bnx2x_cmn.h
@@ -246,10 +246,11 @@ void bnx2x_set_eth_mac_addr_e1(struct bnx2x *bp, int set);
  *
  * @param bp driver handle
  * @param set set or clear the CAM entry
+ * @param force_int use interrupt for the wait (forbid direct polling of fp)
  *
  * @return 0 if cussess, -ENODEV if ramrod doesn't return.
  */
-int bnx2x_set_iscsi_eth_mac_addr(struct bnx2x *bp, int set);
+int bnx2x_set_iscsi_eth_mac_addr(struct bnx2x *bp, int set, int force_int);
 #endif
 
 /**
diff --git a/drivers/net/bnx2x/bnx2x_main.c b/drivers/net/bnx2x/bnx2x_main.c
index edff0d2..379acb2 100644
--- a/drivers/net/bnx2x/bnx2x_main.c
+++ b/drivers/net/bnx2x/bnx2x_main.c
@@ -4929,10 +4929,11 @@ void bnx2x_set_eth_mac_addr_e1(struct bnx2x *bp, int set)
  *
  * @param bp driver handle
  * @param set set or clear the CAM entry
+ * @param force_int use interrupt for the wait (forbid direct polling of fp)
  *
  * @return 0 if cussess, -ENODEV if ramrod doesn't return.
  */
-int bnx2x_set_iscsi_eth_mac_addr(struct bnx2x *bp, int set)
+int bnx2x_set_iscsi_eth_mac_addr(struct bnx2x *bp, int set, int force_int)
 {
 	u32 cl_bit_vec = (1 << BCM_ISCSI_ETH_CL_ID);
 
@@ -4953,7 +4954,7 @@ int bnx2x_set_iscsi_eth_mac_addr(struct bnx2x *bp, int set)
 				   cl_bit_vec, E1H_FUNC_MAX + BP_FUNC(bp));
 
 	/* Wait for a completion when setting */
-	bnx2x_wait_ramrod(bp, 0, 0, &bp->set_mac_pending, set ? 0 : 1);
+	bnx2x_wait_ramrod(bp, 0, 0, &bp->set_mac_pending, force_int ? 0 : (set ? 0 : 1));
 
 	return 0;
 }
@@ -5240,7 +5241,7 @@ void bnx2x_chip_cleanup(struct bnx2x *bp, int unload_mode)
 	/* Clear iSCSI L2 MAC */
 	mutex_lock(&bp->cnic_mutex);
 	if (bp->cnic_flags & BNX2X_CNIC_FLAG_MAC_SET) {
-		bnx2x_set_iscsi_eth_mac_addr(bp, 0);
+		bnx2x_set_iscsi_eth_mac_addr(bp, 0, 0);
 		bp->cnic_flags &= ~BNX2X_CNIC_FLAG_MAC_SET;
 	}
 	mutex_unlock(&bp->cnic_mutex);
@@ -8015,8 +8016,10 @@ static int bnx2x_register_cnic(struct net_device *dev, struct cnic_ops *ops,
 	bnx2x_init_sb(bp, bp->cnic_sb, bp->cnic_sb_mapping, CNIC_SB_ID(bp));
 
 	bnx2x_setup_cnic_irq_info(bp);
-	bnx2x_set_iscsi_eth_mac_addr(bp, 1);
+
+	bnx2x_set_iscsi_eth_mac_addr(bp, 1, 1);
 	bp->cnic_flags |= BNX2X_CNIC_FLAG_MAC_SET;
+
 	rcu_assign_pointer(bp->cnic_ops, ops);
 
 	return 0;
@@ -8030,7 +8033,7 @@ static int bnx2x_unregister_cnic(struct net_device *dev)
 	mutex_lock(&bp->cnic_mutex);
 	if (bp->cnic_flags & BNX2X_CNIC_FLAG_MAC_SET) {
 		bp->cnic_flags &= ~BNX2X_CNIC_FLAG_MAC_SET;
-		bnx2x_set_iscsi_eth_mac_addr(bp, 0);
+		bnx2x_set_iscsi_eth_mac_addr(bp, 0, 1);
 	}
 	cp->drv_state = 0;
 	rcu_assign_pointer(bp->cnic_ops, NULL);