linux-can-fixes-for-6.0-20220810

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Merge tag 'linux-can-fixes-for-6.0-20220810' of git://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can

Marc Kleine-Budde says:

====================
this is a pull request of 4 patches for net/master, with the
whitespace issue fixed.

Fedor Pchelkin contributes 2 fixes for the j1939 CAN protocol.

A patch by me for the ems_usb driver fixes an unaligned access
warning.

Sebastian Würl's patch for the mcp251x driver fixes a race condition
in the receive interrupt.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/can/spi/mcp251x.c

@@ -1070,9 +1070,6 @@ static irqreturn_t mcp251x_can_ist(int irq, void *dev_id)
 
 		mcp251x_read_2regs(spi, CANINTF, &intf, &eflag);
 
-		/* mask out flags we don't care about */
-		intf &= CANINTF_RX | CANINTF_TX | CANINTF_ERR;
-
 		/* receive buffer 0 */
 		if (intf & CANINTF_RX0IF) {
 			mcp251x_hw_rx(spi, 0);
@@ -1082,6 +1079,18 @@ static irqreturn_t mcp251x_can_ist(int irq, void *dev_id)
 			if (mcp251x_is_2510(spi))
 				mcp251x_write_bits(spi, CANINTF,
 						   CANINTF_RX0IF, 0x00);
+
+			/* check if buffer 1 is already known to be full, no need to re-read */
+			if (!(intf & CANINTF_RX1IF)) {
+				u8 intf1, eflag1;
+
+				/* intf needs to be read again to avoid a race condition */
+				mcp251x_read_2regs(spi, CANINTF, &intf1, &eflag1);
+
+				/* combine flags from both operations for error handling */
+				intf |= intf1;
+				eflag |= eflag1;
+			}
 		}
 
 		/* receive buffer 1 */
@@ -1092,6 +1101,9 @@ static irqreturn_t mcp251x_can_ist(int irq, void *dev_id)
 				clear_intf |= CANINTF_RX1IF;
 		}
 
+		/* mask out flags we don't care about */
+		intf &= CANINTF_RX | CANINTF_TX | CANINTF_ERR;
+
 		/* any error or tx interrupt we need to clear? */
 		if (intf & (CANINTF_ERR | CANINTF_TX))
 			clear_intf |= intf & (CANINTF_ERR | CANINTF_TX);

drivers/net/can/usb/ems_usb.c

@@ -195,7 +195,7 @@ struct __packed ems_cpc_msg {
 	__le32 ts_sec;	/* timestamp in seconds */
 	__le32 ts_nsec;	/* timestamp in nano seconds */
 
-	union {
+	union __packed {
 		u8 generic[64];
 		struct cpc_can_msg can_msg;
 		struct cpc_can_params can_params;

net/can/j1939/socket.c

@@ -178,7 +178,10 @@ activate_next:
 	if (!first)
 		return;
 
-	if (WARN_ON_ONCE(j1939_session_activate(first))) {
+	if (j1939_session_activate(first)) {
+		netdev_warn_once(first->priv->ndev,
+				 "%s: 0x%p: Identical session is already activated.\n",
+				 __func__, first);
 		first->err = -EBUSY;
 		goto activate_next;
 	} else {

net/can/j1939/transport.c

@@ -260,6 +260,8 @@ static void __j1939_session_drop(struct j1939_session *session)
 
 static void j1939_session_destroy(struct j1939_session *session)
 {
+	struct sk_buff *skb;
+
 	if (session->transmission) {
 		if (session->err)
 			j1939_sk_errqueue(session, J1939_ERRQUEUE_TX_ABORT);
@@ -274,7 +276,11 @@ static void j1939_session_destroy(struct j1939_session *session)
 	WARN_ON_ONCE(!list_empty(&session->sk_session_queue_entry));
 	WARN_ON_ONCE(!list_empty(&session->active_session_list_entry));
 
-	skb_queue_purge(&session->skb_queue);
+	while ((skb = skb_dequeue(&session->skb_queue)) != NULL) {
+		/* drop ref taken in j1939_session_skb_queue() */
+		skb_unref(skb);
+		kfree_skb(skb);
+	}
 	__j1939_session_drop(session);
 	j1939_priv_put(session->priv);
 	kfree(session);