1 files changed, 89 insertions, 51 deletions

diff --git a/drivers/net/can/rx-offload.c b/drivers/net/can/rx-offload.c
index e6a668ee7730..e8328910a234 100644
--- a/drivers/net/can/rx-offload.c
+++ b/drivers/net/can/rx-offload.c
@@ -1,7 +1,8 @@
 // SPDX-License-Identifier: GPL-2.0-only
-/*
- * Copyright (c) 2014 David Jander, Protonic Holland
- * Copyright (C) 2014-2017 Pengutronix, Marc Kleine-Budde <kernel@pengutronix.de>
+/* Copyright (c) 2014      Protonic Holland,
+ *                         David Jander
+ * Copyright (C) 2014-2017 Pengutronix,
+ *                         Marc Kleine-Budde <kernel@pengutronix.de>
  */
 
 #include <linux/can/dev.h>
@@ -11,14 +12,17 @@ struct can_rx_offload_cb {
 	u32 timestamp;
 };
 
-static inline struct can_rx_offload_cb *can_rx_offload_get_cb(struct sk_buff *skb)
+static inline struct can_rx_offload_cb *
+can_rx_offload_get_cb(struct sk_buff *skb)
 {
 	BUILD_BUG_ON(sizeof(struct can_rx_offload_cb) > sizeof(skb->cb));
 
 	return (struct can_rx_offload_cb *)skb->cb;
 }
 
-static inline bool can_rx_offload_le(struct can_rx_offload *offload, unsigned int a, unsigned int b)
+static inline bool
+can_rx_offload_le(struct can_rx_offload *offload,
+		  unsigned int a, unsigned int b)
 {
 	if (offload->inc)
 		return a <= b;
@@ -26,7 +30,8 @@ static inline bool can_rx_offload_le(struct can_rx_offload *offload, unsigned in
 		return a >= b;
 }
 
-static inline unsigned int can_rx_offload_inc(struct can_rx_offload *offload, unsigned int *val)
+static inline unsigned int
+can_rx_offload_inc(struct can_rx_offload *offload, unsigned int *val)
 {
 	if (offload->inc)
 		return (*val)++;
@@ -36,7 +41,9 @@ static inline unsigned int can_rx_offload_inc(struct can_rx_offload *offload, un
 
 static int can_rx_offload_napi_poll(struct napi_struct *napi, int quota)
 {
-	struct can_rx_offload *offload = container_of(napi, struct can_rx_offload, napi);
+	struct can_rx_offload *offload = container_of(napi,
+						      struct can_rx_offload,
+						      napi);
 	struct net_device *dev = offload->dev;
 	struct net_device_stats *stats = &dev->stats;
 	struct sk_buff *skb;
@@ -65,8 +72,9 @@ static int can_rx_offload_napi_poll(struct napi_struct *napi, int quota)
 	return work_done;
 }
 
-static inline void __skb_queue_add_sort(struct sk_buff_head *head, struct sk_buff *new,
-					int (*compare)(struct sk_buff *a, struct sk_buff *b))
+static inline void
+__skb_queue_add_sort(struct sk_buff_head *head, struct sk_buff *new,
+		     int (*compare)(struct sk_buff *a, struct sk_buff *b))
 {
 	struct sk_buff *pos, *insert = NULL;
 
@@ -101,47 +109,70 @@ static int can_rx_offload_compare(struct sk_buff *a, struct sk_buff *b)
 	cb_a = can_rx_offload_get_cb(a);
 	cb_b = can_rx_offload_get_cb(b);
 
-	/* Substract two u32 and return result as int, to keep
+	/* Subtract two u32 and return result as int, to keep
 	 * difference steady around the u32 overflow.
 	 */
 	return cb_b->timestamp - cb_a->timestamp;
 }
 
-static struct sk_buff *can_rx_offload_offload_one(struct can_rx_offload *offload, unsigned int n)
+/**
+ * can_rx_offload_offload_one() - Read one CAN frame from HW
+ * @offload: pointer to rx_offload context
+ * @n: number of mailbox to read
+ *
+ * The task of this function is to read a CAN frame from mailbox @n
+ * from the device and return the mailbox's content as a struct
+ * sk_buff.
+ *
+ * If the struct can_rx_offload::skb_queue exceeds the maximal queue
+ * length (struct can_rx_offload::skb_queue_len_max) or no skb can be
+ * allocated, the mailbox contents is discarded by reading it into an
+ * overflow buffer. This way the mailbox is marked as free by the
+ * driver.
+ *
+ * Return: A pointer to skb containing the CAN frame on success.
+ *
+ *         NULL if the mailbox @n is empty.
+ *
+ *         ERR_PTR() in case of an error
+ */
+static struct sk_buff *
+can_rx_offload_offload_one(struct can_rx_offload *offload, unsigned int n)
 {
-	struct sk_buff *skb = NULL;
+	struct sk_buff *skb;
 	struct can_rx_offload_cb *cb;
-	struct can_frame *cf;
-	int ret;
+	bool drop = false;
+	u32 timestamp;
 
-	/* If queue is full or skb not available, read to discard mailbox */
-	if (likely(skb_queue_len(&offload->skb_queue) <=
-		   offload->skb_queue_len_max))
-		skb = alloc_can_skb(offload->dev, &cf);
+	/* If queue is full drop frame */
+	if (unlikely(skb_queue_len(&offload->skb_queue) >
+		     offload->skb_queue_len_max))
+		drop = true;
 
-	if (!skb) {
-		struct can_frame cf_overflow;
-		u32 timestamp;
+	skb = offload->mailbox_read(offload, n, &timestamp, drop);
+	/* Mailbox was empty. */
+	if (unlikely(!skb))
+		return NULL;
 
-		ret = offload->mailbox_read(offload, &cf_overflow,
-					    &timestamp, n);
-		if (ret)
-			offload->dev->stats.rx_dropped++;
+	/* There was a problem reading the mailbox, propagate
+	 * error value.
+	 */
+	if (unlikely(IS_ERR(skb))) {
+		offload->dev->stats.rx_dropped++;
+		offload->dev->stats.rx_fifo_errors++;
 
-		return NULL;
+		return skb;
 	}
 
+	/* Mailbox was read. */
 	cb = can_rx_offload_get_cb(skb);
-	ret = offload->mailbox_read(offload, cf, &cb->timestamp, n);
-	if (!ret) {
-		kfree_skb(skb);
-		return NULL;
-	}
+	cb->timestamp = timestamp;
 
 	return skb;
 }
 
-int can_rx_offload_irq_offload_timestamp(struct can_rx_offload *offload, u64 pending)
+int can_rx_offload_irq_offload_timestamp(struct can_rx_offload *offload,
+					 u64 pending)
 {
 	struct sk_buff_head skb_queue;
 	unsigned int i;
@@ -157,8 +188,8 @@ int can_rx_offload_irq_offload_timestamp(struct can_rx_offload *offload, u64 pen
 			continue;
 
 		skb = can_rx_offload_offload_one(offload, i);
-		if (!skb)
-			break;
+		if (IS_ERR_OR_NULL(skb))
+			continue;
 
 		__skb_queue_add_sort(&skb_queue, skb, can_rx_offload_compare);
 	}
@@ -171,8 +202,8 @@ int can_rx_offload_irq_offload_timestamp(struct can_rx_offload *offload, u64 pen
 		skb_queue_splice_tail(&skb_queue, &offload->skb_queue);
 		spin_unlock_irqrestore(&offload->skb_queue.lock, flags);
 
-		if ((queue_len = skb_queue_len(&offload->skb_queue)) >
-		    (offload->skb_queue_len_max / 8))
+		queue_len = skb_queue_len(&offload->skb_queue);
+		if (queue_len > offload->skb_queue_len_max / 8)
 			netdev_dbg(offload->dev, "%s: queue_len=%d\n",
 				   __func__, queue_len);
 
@@ -188,7 +219,13 @@ int can_rx_offload_irq_offload_fifo(struct can_rx_offload *offload)
 	struct sk_buff *skb;
 	int received = 0;
 
-	while ((skb = can_rx_offload_offload_one(offload, 0))) {
+	while (1) {
+		skb = can_rx_offload_offload_one(offload, 0);
+		if (IS_ERR(skb))
+			continue;
+		if (!skb)
+			break;
+
 		skb_queue_tail(&offload->skb_queue, skb);
 		received++;
 	}
@@ -207,8 +244,10 @@ int can_rx_offload_queue_sorted(struct can_rx_offload *offload,
 	unsigned long flags;
 
 	if (skb_queue_len(&offload->skb_queue) >
-	    offload->skb_queue_len_max)
-		return -ENOMEM;
+	    offload->skb_queue_len_max) {
+		kfree_skb(skb);
+		return -ENOBUFS;
+	}
 
 	cb = can_rx_offload_get_cb(skb);
 	cb->timestamp = timestamp;
@@ -250,8 +289,10 @@ int can_rx_offload_queue_tail(struct can_rx_offload *offload,
 			      struct sk_buff *skb)
 {
 	if (skb_queue_len(&offload->skb_queue) >
-	    offload->skb_queue_len_max)
-		return -ENOMEM;
+	    offload->skb_queue_len_max) {
+		kfree_skb(skb);
+		return -ENOBUFS;
+	}
 
 	skb_queue_tail(&offload->skb_queue, skb);
 	can_rx_offload_schedule(offload);
@@ -260,7 +301,9 @@ int can_rx_offload_queue_tail(struct can_rx_offload *offload,
 }
 EXPORT_SYMBOL_GPL(can_rx_offload_queue_tail);
 
-static int can_rx_offload_init_queue(struct net_device *dev, struct can_rx_offload *offload, unsigned int weight)
+static int can_rx_offload_init_queue(struct net_device *dev,
+				     struct can_rx_offload *offload,
+				     unsigned int weight)
 {
 	offload->dev = dev;
 
@@ -269,7 +312,6 @@ static int can_rx_offload_init_queue(struct net_device *dev, struct can_rx_offlo
 	offload->skb_queue_len_max *= 4;
 	skb_queue_head_init(&offload->skb_queue);
 
-	can_rx_offload_reset(offload);
 	netif_napi_add(dev, &offload->napi, can_rx_offload_napi_poll, weight);
 
 	dev_dbg(dev->dev.parent, "%s: skb_queue_len_max=%d\n",
@@ -278,7 +320,8 @@ static int can_rx_offload_init_queue(struct net_device *dev, struct can_rx_offlo
 	return 0;
 }
 
-int can_rx_offload_add_timestamp(struct net_device *dev, struct can_rx_offload *offload)
+int can_rx_offload_add_timestamp(struct net_device *dev,
+				 struct can_rx_offload *offload)
 {
 	unsigned int weight;
 
@@ -298,7 +341,8 @@ int can_rx_offload_add_timestamp(struct net_device *dev, struct can_rx_offload *
 }
 EXPORT_SYMBOL_GPL(can_rx_offload_add_timestamp);
 
-int can_rx_offload_add_fifo(struct net_device *dev, struct can_rx_offload *offload, unsigned int weight)
+int can_rx_offload_add_fifo(struct net_device *dev,
+			    struct can_rx_offload *offload, unsigned int weight)
 {
 	if (!offload->mailbox_read)
 		return -EINVAL;
@@ -309,7 +353,6 @@ EXPORT_SYMBOL_GPL(can_rx_offload_add_fifo);
 
 void can_rx_offload_enable(struct can_rx_offload *offload)
 {
-	can_rx_offload_reset(offload);
 	napi_enable(&offload->napi);
 }
 EXPORT_SYMBOL_GPL(can_rx_offload_enable);
@@ -320,8 +363,3 @@ void can_rx_offload_del(struct can_rx_offload *offload)
 	skb_queue_purge(&offload->skb_queue);
 }
 EXPORT_SYMBOL_GPL(can_rx_offload_del);
-
-void can_rx_offload_reset(struct can_rx_offload *offload)
-{
-}
-EXPORT_SYMBOL_GPL(can_rx_offload_reset);