Re: [openib-general] [PATCH 04/13] Connection Manager

Bryan O'Sullivan
2006-11-17T18:07:34Z

Steve Wise wrote:

> +static void release_tid(struct t3cdev *tdev, u32 hwtid, struct sk_buff *skb)
> +{
> + struct cpl_tid_release *req;
> +
> + skb = get_skb(skb, sizeof *req, GFP_KERNEL);
> + if (!skb) {
> + return;
> + }

Style micronit: no curlies for single-statement blocks.

> +void __free_ep(struct iwch_ep_common *epc)
> +{
> + PDBG("%s ep %p, &refcnt %p state %s, refcnt %d\n",
> + __FUNCTION__, epc, &epc->refcnt,
> + states[state_read(epc)], atomic_read(&epc->refcnt));
> +
> + if (atomic_read(&epc->refcnt) == 1) {
> + goto out;
> + }
> + if (!atomic_dec_and_test(&epc->refcnt)) {
> + return;
> + }
> +out:
> + PDBG("free ep %p\n", epc);
> + kfree(epc);
> +}

Whatever you're trying to do with refcounting and atomics here looks
extremely dodgy and race-prone to me. Why are you using atomic ops in
such a scary manner, instead of just slapping a spinlock around this?

Anyway, please drop this atomic refcounting stuff and use embedded krefs
instead. You're tunnelling into a bug mine.

By the way, it would be more consistent with normal kernel naming
conventions to name these refcount-diddling routines ep_get and ep_put,
since __ep_free doesn't actually free an object unless it feels like it.

> +int __init iwch_cm_init(void)
> +{
> + skb_queue_head_init(&rxq);
> +
> + workq = create_singlethread_workqueue("iw_cxgb3");
> + if (!workq)
> + return -ENOMEM;
> +
> + /*
> + * All upcalls from the T3 Core go to sched() to
> + * schedule the processing on a work queue.
> + */
> + t3c_handlers[CPL_ACT_ESTABLISH] = sched;
> + t3c_handlers[CPL_ACT_OPEN_RPL] = sched;
> + t3c_handlers[CPL_RX_DATA] = sched;
> + t3c_handlers[CPL_TX_DMA_ACK] = sched;
> + t3c_handlers[CPL_ABORT_RPL_RSS] = sched;
> + t3c_handlers[CPL_ABORT_RPL] = sched;
> + t3c_handlers[CPL_PASS_OPEN_RPL] = sched;
> + t3c_handlers[CPL_CLOSE_LISTSRV_RPL] = sched;
> + t3c_handlers[CPL_PASS_ACCEPT_REQ] = sched;
> + t3c_handlers[CPL_PASS_ESTABLISH] = sched;
> + t3c_handlers[CPL_PEER_CLOSE] = sched;
> + t3c_handlers[CPL_CLOSE_CON_RPL] = sched;
> + t3c_handlers[CPL_ABORT_REQ_RSS] = sched;
> + t3c_handlers[CPL_RDMA_TERMINATE] = sched;
> + t3c_handlers[CPL_RDMA_EC_STATUS] = sched;
> +
> + /*
> + * These are the real handlers that are called from a
> + * work queue.
> + */
> + work_handlers[CPL_ACT_ESTABLISH] = act_establish;
> + work_handlers[CPL_ACT_OPEN_RPL] = act_open_rpl;
> + work_handlers[CPL_RX_DATA] = rx_data;
> + work_handlers[CPL_TX_DMA_ACK] = tx_ack;
> + work_handlers[CPL_ABORT_RPL_RSS] = abort_rpl;
> + work_handlers[CPL_ABORT_RPL] = abort_rpl;
> + work_handlers[CPL_PASS_OPEN_RPL] = pass_open_rpl;
> + work_handlers[CPL_CLOSE_LISTSRV_RPL] = close_listsrv_rpl;
> + work_handlers[CPL_PASS_ACCEPT_REQ] = pass_accept_req;
> + work_handlers[CPL_PASS_ESTABLISH] = pass_establish;
> + work_handlers[CPL_PEER_CLOSE] = peer_close;
> + work_handlers[CPL_ABORT_REQ_RSS] = peer_abort;
> + work_handlers[CPL_CLOSE_CON_RPL] = close_con_rpl;
> + work_handlers[CPL_RDMA_TERMINATE] = terminate;
> + work_handlers[CPL_RDMA_EC_STATUS] = ec_status;
> + return 0;
> +}

This seems mighty peculiar. Why aren't you keeping this stuff in
structs, instead of faking up structs via arrays?

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