can: mcp251x: fix endless loop in interrupt handler if CANINTF_MERRF is set

Commit d3cd15657516141adce387810be8cb377baf020e introduced a bug, the
interrupt handler would loop endlessly if the CANINTF_MERRF bit is set,
because it's not cleared.

This patch fixes the problem by masking out the CANINTF_MERRF and all other
non interesting bits.

Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 5 deletions

diff --git a/drivers/net/can/mcp251x.c b/drivers/net/can/mcp251x.c
index c664be261e98..59f40bce1ffc 100644
--- a/drivers/net/can/mcp251x.c
+++ b/drivers/net/can/mcp251x.c
@@ -125,8 +125,9 @@
 #  define CANINTF_TX0IF 0x04
 #  define CANINTF_RX1IF 0x02
 #  define CANINTF_RX0IF 0x01
-#  define CANINTF_ERR_TX \
-        (CANINTF_ERRIF | CANINTF_TX2IF | CANINTF_TX1IF | CANINTF_TX0IF)
+#  define CANINTF_RX (CANINTF_RX0IF | CANINTF_RX1IF)
+#  define CANINTF_TX (CANINTF_TX2IF | CANINTF_TX1IF | CANINTF_TX0IF)
+#  define CANINTF_ERR (CANINTF_ERRIF)
 #define EFLG          0x2d
 #  define EFLG_EWARN    0x01
 #  define EFLG_RXWAR    0x02
@@ -790,6 +791,9 @@ 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);
@@ -810,8 +814,8 @@ static irqreturn_t mcp251x_can_ist(int irq, void *dev_id)
                 }
 
                 /* any error or tx interrupt we need to clear? */
-                if (intf & CANINTF_ERR_TX)
-                        clear_intf |= intf & CANINTF_ERR_TX;
+                if (intf & (CANINTF_ERR | CANINTF_TX))
+                        clear_intf |= intf & (CANINTF_ERR | CANINTF_TX);
                 if (clear_intf)
                         mcp251x_write_bits(spi, CANINTF, clear_intf, 0x00);
 
@@ -887,7 +891,7 @@ static irqreturn_t mcp251x_can_ist(int irq, void *dev_id)
                 if (intf == 0)
                         break;
 
-                if (intf & (CANINTF_TX2IF | CANINTF_TX1IF | CANINTF_TX0IF)) {
+                if (intf & CANINTF_TX) {
                         net->stats.tx_packets++;
                         net->stats.tx_bytes += priv->tx_len - 1;
                         if (priv->tx_len) {