Merge branch 'bnxt_en-rtnl-fixes'

Michael Chan says:

====================
bnxt_en: Fix RTNL lock usage in bnxt_sp_task().

There are 2 function calls from bnxt_sp_task() that have buggy RTNL
usage.  These 2 functions take RTNL lock under some conditions, but
some callers (such as open, ethtool) have already taken RTNL.  These
3 patches fix the issue by making it clear that callers must take
RTNL.  If the caller is bnxt_sp_task() which does not automatically
take RTNL, we add a common scheme for bnxt_sp_task() to call these
functions properly under RTNL.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bnxt/bnxt.c

@@ -5314,17 +5314,12 @@ static int bnxt_update_link(struct bnxt *bp, bool chng_link_state)
 	if ((link_info->support_auto_speeds | diff) !=
 	    link_info->support_auto_speeds) {
 		/* An advertised speed is no longer supported, so we need to
-		 * update the advertisement settings.  See bnxt_reset() for
-		 * comments about the rtnl_lock() sequence below.
+		 * update the advertisement settings.  Caller holds RTNL
+		 * so we can modify link settings.
 		 */
-		clear_bit(BNXT_STATE_IN_SP_TASK, &bp->state);
-		rtnl_lock();
 		link_info->advertising = link_info->support_auto_speeds;
-		if (test_bit(BNXT_STATE_OPEN, &bp->state) &&
-		    (link_info->autoneg & BNXT_AUTONEG_SPEED))
+		if (link_info->autoneg & BNXT_AUTONEG_SPEED)
 			bnxt_hwrm_set_link_setting(bp, true, false);
-		set_bit(BNXT_STATE_IN_SP_TASK, &bp->state);
-		rtnl_unlock();
 	}
 	return 0;
 }
@@ -6200,29 +6195,37 @@ static void bnxt_timer(unsigned long data)
 	mod_timer(&bp->timer, jiffies + bp->current_interval);
 }
 
-/* Only called from bnxt_sp_task() */
-static void bnxt_reset(struct bnxt *bp, bool silent)
+static void bnxt_rtnl_lock_sp(struct bnxt *bp)
 {
-	/* bnxt_reset_task() calls bnxt_close_nic() which waits
-	 * for BNXT_STATE_IN_SP_TASK to clear.
-	 * If there is a parallel dev_close(), bnxt_close() may be holding
+	/* We are called from bnxt_sp_task which has BNXT_STATE_IN_SP_TASK
+	 * set.  If the device is being closed, bnxt_close() may be holding
 	 * rtnl() and waiting for BNXT_STATE_IN_SP_TASK to clear.  So we
 	 * must clear BNXT_STATE_IN_SP_TASK before holding rtnl().
 	 */
 	clear_bit(BNXT_STATE_IN_SP_TASK, &bp->state);
 	rtnl_lock();
-	if (test_bit(BNXT_STATE_OPEN, &bp->state))
-		bnxt_reset_task(bp, silent);
+}
+
+static void bnxt_rtnl_unlock_sp(struct bnxt *bp)
+{
 	set_bit(BNXT_STATE_IN_SP_TASK, &bp->state);
 	rtnl_unlock();
 }
 
+/* Only called from bnxt_sp_task() */
+static void bnxt_reset(struct bnxt *bp, bool silent)
+{
+	bnxt_rtnl_lock_sp(bp);
+	if (test_bit(BNXT_STATE_OPEN, &bp->state))
+		bnxt_reset_task(bp, silent);
+	bnxt_rtnl_unlock_sp(bp);
+}
+
 static void bnxt_cfg_ntp_filters(struct bnxt *);
 
 static void bnxt_sp_task(struct work_struct *work)
 {
 	struct bnxt *bp = container_of(work, struct bnxt, sp_task);
-	int rc;
 
 	set_bit(BNXT_STATE_IN_SP_TASK, &bp->state);
 	smp_mb__after_atomic();
@@ -6236,16 +6239,6 @@ static void bnxt_sp_task(struct work_struct *work)
 
 	if (test_and_clear_bit(BNXT_RX_NTP_FLTR_SP_EVENT, &bp->sp_event))
 		bnxt_cfg_ntp_filters(bp);
-	if (test_and_clear_bit(BNXT_LINK_CHNG_SP_EVENT, &bp->sp_event)) {
-		if (test_and_clear_bit(BNXT_LINK_SPEED_CHNG_SP_EVENT,
-				       &bp->sp_event))
-			bnxt_hwrm_phy_qcaps(bp);
-
-		rc = bnxt_update_link(bp, true);
-		if (rc)
-			netdev_err(bp->dev, "SP task can't update link (rc: %x)\n",
-				   rc);
-	}
 	if (test_and_clear_bit(BNXT_HWRM_EXEC_FWD_REQ_SP_EVENT, &bp->sp_event))
 		bnxt_hwrm_exec_fwd_req(bp);
 	if (test_and_clear_bit(BNXT_VXLAN_ADD_PORT_SP_EVENT, &bp->sp_event)) {
@@ -6266,18 +6259,39 @@ static void bnxt_sp_task(struct work_struct *work)
 		bnxt_hwrm_tunnel_dst_port_free(
 			bp, TUNNEL_DST_PORT_FREE_REQ_TUNNEL_TYPE_GENEVE);
 	}
+	if (test_and_clear_bit(BNXT_PERIODIC_STATS_SP_EVENT, &bp->sp_event))
+		bnxt_hwrm_port_qstats(bp);
+
+	/* These functions below will clear BNXT_STATE_IN_SP_TASK.  They
+	 * must be the last functions to be called before exiting.
+	 */
+	if (test_and_clear_bit(BNXT_LINK_CHNG_SP_EVENT, &bp->sp_event)) {
+		int rc = 0;
+
+		if (test_and_clear_bit(BNXT_LINK_SPEED_CHNG_SP_EVENT,
+				       &bp->sp_event))
+			bnxt_hwrm_phy_qcaps(bp);
+
+		bnxt_rtnl_lock_sp(bp);
+		if (test_bit(BNXT_STATE_OPEN, &bp->state))
+			rc = bnxt_update_link(bp, true);
+		bnxt_rtnl_unlock_sp(bp);
+		if (rc)
+			netdev_err(bp->dev, "SP task can't update link (rc: %x)\n",
+				   rc);
+	}
+	if (test_and_clear_bit(BNXT_HWRM_PORT_MODULE_SP_EVENT, &bp->sp_event)) {
+		bnxt_rtnl_lock_sp(bp);
+		if (test_bit(BNXT_STATE_OPEN, &bp->state))
+			bnxt_get_port_module_status(bp);
+		bnxt_rtnl_unlock_sp(bp);
+	}
 	if (test_and_clear_bit(BNXT_RESET_TASK_SP_EVENT, &bp->sp_event))
 		bnxt_reset(bp, false);
 
 	if (test_and_clear_bit(BNXT_RESET_TASK_SILENT_SP_EVENT, &bp->sp_event))
 		bnxt_reset(bp, true);
 
-	if (test_and_clear_bit(BNXT_HWRM_PORT_MODULE_SP_EVENT, &bp->sp_event))
-		bnxt_get_port_module_status(bp);
-
-	if (test_and_clear_bit(BNXT_PERIODIC_STATS_SP_EVENT, &bp->sp_event))
-		bnxt_hwrm_port_qstats(bp);
-
 	smp_mb__before_atomic();
 	clear_bit(BNXT_STATE_IN_SP_TASK, &bp->state);
 }