can: c_can: Make it SMP safe

The hardware has two message control interfaces, but the code only uses the
first one. So on SMP the following can be observed:

CPU0 	       	CPU1
rx_poll()
  write IF1	xmit()
		write IF1
  write IF1

That results in corrupted message object configurations. The TX/RX is not
globally serialized it's only serialized on a core.

Simple solution: Let RX use IF1 and TX use IF2 and all is good.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

1 files changed, 21 insertions, 15 deletions

diff --git a/drivers/net/can/c_can/c_can.c b/drivers/net/can/c_can/c_can.c
index 4d08a32f27ac..38f9adaf15ac 100644
--- a/drivers/net/can/c_can/c_can.c
+++ b/drivers/net/can/c_can/c_can.c
@@ -133,6 +133,12 @@
 #define IF_MCONT_DLC_MASK       0xf
 
 /*
+ * Use IF1 for RX and IF2 for TX
+ */
+#define IF_RX                   0
+#define IF_TX                   1
+
+/*
  * IFx register masks:
  * allow easy operation on 16-bit registers when the
  * argument is 32-bit instead
@@ -420,7 +426,7 @@ static void c_can_handle_lost_msg_obj(struct net_device *dev,
         priv->write_reg(priv, C_CAN_IFACE(MSGCTRL_REG, iface),
                         IF_MCONT_CLR_MSGLST);
 
-        c_can_object_put(dev, 0, objno, IF_COMM_CONTROL);
+        c_can_object_put(dev, iface, objno, IF_COMM_CONTROL);
 
         /* create an error msg */
         skb = alloc_can_err_skb(dev, &frame);
@@ -551,7 +557,7 @@ static netdev_tx_t c_can_start_xmit(struct sk_buff *skb,
         msg_obj_no = get_tx_next_msg_obj(priv);
 
         /* prepare message object for transmission */
-        c_can_write_msg_object(dev, 0, frame, msg_obj_no);
+        c_can_write_msg_object(dev, IF_TX, frame, msg_obj_no);
         can_put_echo_skb(skb, dev, msg_obj_no - C_CAN_MSG_OBJ_TX_FIRST);
 
         /*
@@ -634,14 +640,14 @@ static void c_can_configure_msg_objects(struct net_device *dev)
 
         /* first invalidate all message objects */
         for (i = C_CAN_MSG_OBJ_RX_FIRST; i <= C_CAN_NO_OF_OBJECTS; i++)
-                c_can_inval_msg_object(dev, 0, i);
+                c_can_inval_msg_object(dev, IF_RX, i);
 
         /* setup receive message objects */
         for (i = C_CAN_MSG_OBJ_RX_FIRST; i < C_CAN_MSG_OBJ_RX_LAST; i++)
-                c_can_setup_receive_object(dev, 0, i, 0, 0,
+                c_can_setup_receive_object(dev, IF_RX, i, 0, 0,
                         (IF_MCONT_RXIE | IF_MCONT_UMASK) & ~IF_MCONT_EOB);
 
-        c_can_setup_receive_object(dev, 0, C_CAN_MSG_OBJ_RX_LAST, 0, 0,
+        c_can_setup_receive_object(dev, IF_RX, C_CAN_MSG_OBJ_RX_LAST, 0, 0,
                         IF_MCONT_EOB | IF_MCONT_RXIE | IF_MCONT_UMASK);
 }
 
@@ -792,13 +798,13 @@ static void c_can_do_tx(struct net_device *dev)
                 if (!(val & (1 << (msg_obj_no - 1)))) {
                         can_get_echo_skb(dev,
                                         msg_obj_no - C_CAN_MSG_OBJ_TX_FIRST);
-                        c_can_object_get(dev, 0, msg_obj_no, IF_COMM_ALL);
+                        c_can_object_get(dev, IF_TX, msg_obj_no, IF_COMM_ALL);
                         stats->tx_bytes += priv->read_reg(priv,
-                                        C_CAN_IFACE(MSGCTRL_REG, 0))
+                                        C_CAN_IFACE(MSGCTRL_REG, IF_TX))
                                         & IF_MCONT_DLC_MASK;
                         stats->tx_packets++;
                         can_led_event(dev, CAN_LED_EVENT_TX);
-                        c_can_inval_msg_object(dev, 0, msg_obj_no);
+                        c_can_inval_msg_object(dev, IF_TX, msg_obj_no);
                 } else {
                         break;
                 }
@@ -850,13 +856,13 @@ static int c_can_do_rx_poll(struct net_device *dev, int quota)
                 while ((msg_obj = ffs(val)) && quota > 0) {
                         val &= ~BIT(msg_obj - 1);
 
-                        c_can_object_get(dev, 0, msg_obj, IF_COMM_ALL &
+                        c_can_object_get(dev, IF_RX, msg_obj, IF_COMM_ALL &
                                         ~IF_COMM_TXRQST);
                         msg_ctrl_save = priv->read_reg(priv,
-                                        C_CAN_IFACE(MSGCTRL_REG, 0));
+                                        C_CAN_IFACE(MSGCTRL_REG, IF_RX));
 
                         if (msg_ctrl_save & IF_MCONT_MSGLST) {
-                                c_can_handle_lost_msg_obj(dev, 0, msg_obj);
+                                c_can_handle_lost_msg_obj(dev, IF_RX, msg_obj);
                                 num_rx_pkts++;
                                 quota--;
                                 continue;
@@ -869,19 +875,19 @@ static int c_can_do_rx_poll(struct net_device *dev, int quota)
                                 continue;
 
                         /* read the data from the message object */
-                        c_can_read_msg_object(dev, 0, msg_ctrl_save);
+                        c_can_read_msg_object(dev, IF_RX, msg_ctrl_save);
 
                         if (msg_obj < C_CAN_MSG_RX_LOW_LAST)
-                                c_can_mark_rx_msg_obj(dev, 0,
+                                c_can_mark_rx_msg_obj(dev, IF_RX,
                                                 msg_ctrl_save, msg_obj);
                         else if (msg_obj > C_CAN_MSG_RX_LOW_LAST)
                                 /* activate this msg obj */
-                                c_can_activate_rx_msg_obj(dev, 0,
+                                c_can_activate_rx_msg_obj(dev, IF_RX,
                                                 msg_ctrl_save, msg_obj);
                         else if (msg_obj == C_CAN_MSG_RX_LOW_LAST)
                                 /* activate all lower message objects */
                                 c_can_activate_all_lower_rx_msg_obj(dev,
-                                                0, msg_ctrl_save);
+                                                IF_RX, msg_ctrl_save);
 
                         num_rx_pkts++;
                         quota--;