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Commit 640916db authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Marc Kleine-Budde
Browse files

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: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarMarc Kleine-Budde <mkl@pengutronix.de>
parent 5bb9cbaa

drivers/net/can/c_can/c_can.c

+21 −15
Original line number Diff line number Diff line
@@ -132,6 +132,12 @@ 
#define IF_MCONT_EOB		BIT(7)

#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
@@ -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--;