firewire: net: replace lists by counters
The current transmit code does not at all make use of - fwnet_device.packet_list and only very limited use of - fwnet_device.broadcasted_list, - fwnet_device.queued_packets. Their current function is to track whether the TX soft-IRQ finished dealing with an skb when the AT-req tasklet takes over, and to discard pending tx datagrams (if there are any) when the local node is removed. The latter does actually contain a race condition bug with TX soft-IRQ and AT-req tasklet. Instead of these lists and the corresponding link in fwnet_packet_task, - a flag in fwnet_packet_task to track whether fwnet_tx is done, - a counter of queued datagrams in fwnet_device do the job as well. The above mentioned theoretic race condition is resolved by letting fwnet_remove sleep until all datagrams were flushed. It may sleep almost arbitrarily long since fwnet_remove is executed in the context of a multithreaded (concurrency managed) workqueue. The type of max_payload is changed to u16 here to avoid waste in struct fwnet_packet_task. This value cannot exceed 4096 per IEEE 1394:2008 table 16-18 (or 32678 per specification of packet headers, if there is ever going to be something else than beta mode). Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
This commit is contained in:
Stefan Richter
parent
7ee11fa8d0
commit
48553011ce
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@ -7,6 +7,7 @@
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*/
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#include <linux/bug.h>
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#include <linux/delay.h>
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#include <linux/device.h>
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#include <linux/firewire.h>
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#include <linux/firewire-constants.h>
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@ -169,15 +170,8 @@ struct fwnet_device {
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struct fw_address_handler handler;
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u64 local_fifo;
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/* List of packets to be sent */
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struct list_head packet_list;
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/*
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* List of packets that were broadcasted. When we get an ISO interrupt
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* one of them has been sent
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*/
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struct list_head broadcasted_list;
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/* List of packets that have been sent but not yet acked */
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struct list_head sent_list;
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/* Number of tx datagrams that have been queued but not yet acked */
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int queued_datagrams;
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struct list_head peer_list;
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struct fw_card *card;
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@ -195,7 +189,7 @@ struct fwnet_peer {
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unsigned pdg_size; /* pd_list size */
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u16 datagram_label; /* outgoing datagram label */
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unsigned max_payload; /* includes RFC2374_FRAG_HDR_SIZE overhead */
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u16 max_payload; /* includes RFC2374_FRAG_HDR_SIZE overhead */
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int node_id;
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int generation;
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unsigned speed;
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@ -203,22 +197,18 @@ struct fwnet_peer {
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/* This is our task struct. It's used for the packet complete callback. */
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struct fwnet_packet_task {
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/*
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* ptask can actually be on dev->packet_list, dev->broadcasted_list,
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* or dev->sent_list depending on its current state.
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*/
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struct list_head pt_link;
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struct fw_transaction transaction;
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struct rfc2734_header hdr;
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struct sk_buff *skb;
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struct fwnet_device *dev;
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int outstanding_pkts;
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unsigned max_payload;
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u64 fifo_addr;
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u16 dest_node;
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u16 max_payload;
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u8 generation;
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u8 speed;
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u8 enqueued;
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};
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/*
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@ -915,9 +905,9 @@ static void fwnet_transmit_packet_done(struct fwnet_packet_task *ptask)
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ptask->outstanding_pkts--;
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/* Check whether we or the networking TX soft-IRQ is last user. */
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free = (ptask->outstanding_pkts == 0 && !list_empty(&ptask->pt_link));
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free = (ptask->outstanding_pkts == 0 && ptask->enqueued);
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if (free)
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list_del(&ptask->pt_link);
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dev->queued_datagrams--;
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if (ptask->outstanding_pkts == 0) {
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dev->netdev->stats.tx_packets++;
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@ -986,9 +976,9 @@ static void fwnet_transmit_packet_failed(struct fwnet_packet_task *ptask)
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ptask->outstanding_pkts = 0;
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/* Check whether we or the networking TX soft-IRQ is last user. */
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free = !list_empty(&ptask->pt_link);
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free = ptask->enqueued;
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if (free)
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list_del(&ptask->pt_link);
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dev->queued_datagrams--;
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dev->netdev->stats.tx_dropped++;
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dev->netdev->stats.tx_errors++;
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@ -1069,9 +1059,11 @@ static int fwnet_send_packet(struct fwnet_packet_task *ptask)
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spin_lock_irqsave(&dev->lock, flags);
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/* If the AT tasklet already ran, we may be last user. */
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free = (ptask->outstanding_pkts == 0 && list_empty(&ptask->pt_link));
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free = (ptask->outstanding_pkts == 0 && !ptask->enqueued);
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if (!free)
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list_add_tail(&ptask->pt_link, &dev->broadcasted_list);
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ptask->enqueued = true;
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else
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dev->queued_datagrams--;
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spin_unlock_irqrestore(&dev->lock, flags);
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@ -1086,9 +1078,11 @@ static int fwnet_send_packet(struct fwnet_packet_task *ptask)
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spin_lock_irqsave(&dev->lock, flags);
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/* If the AT tasklet already ran, we may be last user. */
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free = (ptask->outstanding_pkts == 0 && list_empty(&ptask->pt_link));
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free = (ptask->outstanding_pkts == 0 && !ptask->enqueued);
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if (!free)
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list_add_tail(&ptask->pt_link, &dev->sent_list);
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ptask->enqueued = true;
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else
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dev->queued_datagrams--;
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spin_unlock_irqrestore(&dev->lock, flags);
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@ -1350,10 +1344,12 @@ static netdev_tx_t fwnet_tx(struct sk_buff *skb, struct net_device *net)
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max_payload += RFC2374_FRAG_HDR_SIZE;
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}
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dev->queued_datagrams++;
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spin_unlock_irqrestore(&dev->lock, flags);
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ptask->max_payload = max_payload;
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INIT_LIST_HEAD(&ptask->pt_link);
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ptask->enqueued = 0;
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fwnet_send_packet(ptask);
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@ -1487,14 +1483,9 @@ static int fwnet_probe(struct device *_dev)
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dev->broadcast_rcv_context = NULL;
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dev->broadcast_xmt_max_payload = 0;
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dev->broadcast_xmt_datagramlabel = 0;
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dev->local_fifo = FWNET_NO_FIFO_ADDR;
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INIT_LIST_HEAD(&dev->packet_list);
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INIT_LIST_HEAD(&dev->broadcasted_list);
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INIT_LIST_HEAD(&dev->sent_list);
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dev->queued_datagrams = 0;
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INIT_LIST_HEAD(&dev->peer_list);
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dev->card = card;
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dev->netdev = net;
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@ -1552,7 +1543,7 @@ static int fwnet_remove(struct device *_dev)
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struct fwnet_peer *peer = dev_get_drvdata(_dev);
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struct fwnet_device *dev = peer->dev;
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struct net_device *net;
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struct fwnet_packet_task *ptask, *pt_next;
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int i;
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mutex_lock(&fwnet_device_mutex);
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@ -1570,21 +1561,9 @@ static int fwnet_remove(struct device *_dev)
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dev->card);
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fw_iso_context_destroy(dev->broadcast_rcv_context);
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}
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list_for_each_entry_safe(ptask, pt_next,
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&dev->packet_list, pt_link) {
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dev_kfree_skb_any(ptask->skb);
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kmem_cache_free(fwnet_packet_task_cache, ptask);
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}
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list_for_each_entry_safe(ptask, pt_next,
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&dev->broadcasted_list, pt_link) {
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dev_kfree_skb_any(ptask->skb);
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kmem_cache_free(fwnet_packet_task_cache, ptask);
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}
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list_for_each_entry_safe(ptask, pt_next,
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&dev->sent_list, pt_link) {
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dev_kfree_skb_any(ptask->skb);
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kmem_cache_free(fwnet_packet_task_cache, ptask);
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}
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for (i = 0; dev->queued_datagrams && i < 5; i++)
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ssleep(1);
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WARN_ON(dev->queued_datagrams);
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list_del(&dev->dev_link);
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free_netdev(net);
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