diff options
| -rw-r--r-- | drivers/net/can/rx-offload.c | 86 |
1 files changed, 73 insertions, 13 deletions
diff --git a/drivers/net/can/rx-offload.c b/drivers/net/can/rx-offload.c index 16af09c71cfe..1b3ce70c55bc 100644 --- a/drivers/net/can/rx-offload.c +++ b/drivers/net/can/rx-offload.c @@ -116,39 +116,95 @@ static int can_rx_offload_compare(struct sk_buff *a, struct sk_buff *b) 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 = NULL, *skb_error = NULL; struct can_rx_offload_cb *cb; struct can_frame *cf; int ret; - /* 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)) + offload->skb_queue_len_max)) { skb = alloc_can_skb(offload->dev, &cf); + if (unlikely(!skb)) + skb_error = ERR_PTR(-ENOMEM); /* skb alloc failed */ + } else { + skb_error = ERR_PTR(-ENOBUFS); /* skb_queue is full */ + } - if (!skb) { + /* If queue is full or skb not available, drop by reading into + * overflow buffer. + */ + if (unlikely(skb_error)) { struct can_frame cf_overflow; u32 timestamp; ret = offload->mailbox_read(offload, &cf_overflow, ×tamp, n); - if (ret) { - offload->dev->stats.rx_dropped++; - offload->dev->stats.rx_fifo_errors++; - } - return NULL; + /* Mailbox was empty. */ + if (unlikely(!ret)) + return NULL; + + /* Mailbox has been read and we're dropping it or + * there was a problem reading the mailbox. + * + * Increment error counters in any case. + */ + offload->dev->stats.rx_dropped++; + offload->dev->stats.rx_fifo_errors++; + + /* There was a problem reading the mailbox, propagate + * error value. + */ + if (unlikely(ret < 0)) + return ERR_PTR(ret); + + return skb_error; } cb = can_rx_offload_get_cb(skb); ret = offload->mailbox_read(offload, cf, &cb->timestamp, n); - if (!ret) { + + /* Mailbox was empty. */ + if (unlikely(!ret)) { kfree_skb(skb); return NULL; } + /* There was a problem reading the mailbox, propagate error value. */ + if (unlikely(ret < 0)) { + kfree_skb(skb); + + offload->dev->stats.rx_dropped++; + offload->dev->stats.rx_fifo_errors++; + + return ERR_PTR(ret); + } + + /* Mailbox was read. */ return skb; } @@ -168,7 +224,7 @@ 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) + if (IS_ERR_OR_NULL(skb)) break; __skb_queue_add_sort(&skb_queue, skb, can_rx_offload_compare); @@ -199,7 +255,11 @@ 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_OR_NULL(skb)) + break; + skb_queue_tail(&offload->skb_queue, skb); received++; } |