Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751430Ab3HSUhr (ORCPT ); Mon, 19 Aug 2013 16:37:47 -0400 Received: from mga09.intel.com ([134.134.136.24]:9009 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751169Ab3HSUhd (ORCPT ); Mon, 19 Aug 2013 16:37:33 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.89,914,1367996400"; d="scan'208";a="389732126" Date: Mon, 19 Aug 2013 13:37:31 -0700 From: Jon Mason To: Dan Williams Cc: Linux Kernel Mailing List , Vinod Koul , Dave Jiang Subject: Re: [PATCH 09/15] NTB: Use DMA Engine to Transmit and Receive Message-ID: <20130819203730.GB22169@jonmason-lab> References: <1375464944-27914-1-git-send-email-jon.mason@intel.com> <1375464944-27914-10-git-send-email-jon.mason@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 24778 Lines: 639 On Mon, Aug 19, 2013 at 03:01:54AM -0700, Dan Williams wrote: > On Fri, Aug 2, 2013 at 10:35 AM, Jon Mason wrote: > > Allocate and use a DMA engine channel to transmit and receive data over > > NTB. If none is allocated, fall back to using the CPU to transfer data. > > > > Cc: Dan Williams > > Cc: Vinod Koul > > Cc: Dave Jiang > > Signed-off-by: Jon Mason > > --- > > drivers/ntb/ntb_hw.c | 17 +++ > > drivers/ntb/ntb_hw.h | 1 + > > drivers/ntb/ntb_transport.c | 285 ++++++++++++++++++++++++++++++++++++------- > > 3 files changed, 258 insertions(+), 45 deletions(-) > > > > diff --git a/drivers/ntb/ntb_hw.c b/drivers/ntb/ntb_hw.c > > index 1d8e551..014222c 100644 > > --- a/drivers/ntb/ntb_hw.c > > +++ b/drivers/ntb/ntb_hw.c > > @@ -350,6 +350,23 @@ int ntb_read_remote_spad(struct ntb_device *ndev, unsigned int idx, u32 *val) > > } > > > > /** > > + * ntb_get_mw_base() - get addr for the NTB memory window > > + * @ndev: pointer to ntb_device instance > > + * @mw: memory window number > > + * > > + * This function provides the base address of the memory window specified. > > + * > > + * RETURNS: address, or NULL on error. > > + */ > > +resource_size_t ntb_get_mw_base(struct ntb_device *ndev, unsigned int mw) > > +{ > > + if (mw >= ntb_max_mw(ndev)) > > + return 0; > > + > > + return pci_resource_start(ndev->pdev, MW_TO_BAR(mw)); > > +} > > + > > +/** > > * ntb_get_mw_vbase() - get virtual addr for the NTB memory window > > * @ndev: pointer to ntb_device instance > > * @mw: memory window number > > diff --git a/drivers/ntb/ntb_hw.h b/drivers/ntb/ntb_hw.h > > index b03de80..ab5f768 100644 > > --- a/drivers/ntb/ntb_hw.h > > +++ b/drivers/ntb/ntb_hw.h > > @@ -240,6 +240,7 @@ int ntb_write_local_spad(struct ntb_device *ndev, unsigned int idx, u32 val); > > int ntb_read_local_spad(struct ntb_device *ndev, unsigned int idx, u32 *val); > > int ntb_write_remote_spad(struct ntb_device *ndev, unsigned int idx, u32 val); > > int ntb_read_remote_spad(struct ntb_device *ndev, unsigned int idx, u32 *val); > > +resource_size_t ntb_get_mw_base(struct ntb_device *ndev, unsigned int mw); > > void __iomem *ntb_get_mw_vbase(struct ntb_device *ndev, unsigned int mw); > > u64 ntb_get_mw_size(struct ntb_device *ndev, unsigned int mw); > > void ntb_ring_sdb(struct ntb_device *ndev, unsigned int idx); > > diff --git a/drivers/ntb/ntb_transport.c b/drivers/ntb/ntb_transport.c > > index f7380e9..73a35e4 100644 > > --- a/drivers/ntb/ntb_transport.c > > +++ b/drivers/ntb/ntb_transport.c > > @@ -47,6 +47,7 @@ > > */ > > #include > > #include > > +#include > > #include > > #include > > #include > > @@ -68,6 +69,10 @@ static unsigned char max_num_clients; > > module_param(max_num_clients, byte, 0644); > > MODULE_PARM_DESC(max_num_clients, "Maximum number of NTB transport clients"); > > > > +static unsigned int copy_bytes = 1024; > > +module_param(copy_bytes, uint, 0644); > > +MODULE_PARM_DESC(copy_bytes, "Threshold under which NTB will use the CPU to copy instead of DMA"); > > + > > struct ntb_queue_entry { > > /* ntb_queue list reference */ > > struct list_head entry; > > @@ -76,6 +81,13 @@ struct ntb_queue_entry { > > void *buf; > > unsigned int len; > > unsigned int flags; > > + > > + struct ntb_transport_qp *qp; > > + union { > > + struct ntb_payload_header __iomem *tx_hdr; > > + struct ntb_payload_header *rx_hdr; > > + }; > > + unsigned int index; > > }; > > > > struct ntb_rx_info { > > @@ -86,6 +98,7 @@ struct ntb_transport_qp { > > struct ntb_transport *transport; > > struct ntb_device *ndev; > > void *cb_data; > > + struct dma_chan *dma_chan; > > > > bool client_ready; > > bool qp_link; > > @@ -99,6 +112,7 @@ struct ntb_transport_qp { > > struct list_head tx_free_q; > > spinlock_t ntb_tx_free_q_lock; > > void __iomem *tx_mw; > > + dma_addr_t tx_mw_raw; > > unsigned int tx_index; > > unsigned int tx_max_entry; > > unsigned int tx_max_frame; > > @@ -114,6 +128,7 @@ struct ntb_transport_qp { > > unsigned int rx_index; > > unsigned int rx_max_entry; > > unsigned int rx_max_frame; > > + dma_cookie_t last_cookie; > > > > void (*event_handler) (void *data, int status); > > struct delayed_work link_work; > > @@ -129,9 +144,14 @@ struct ntb_transport_qp { > > u64 rx_err_no_buf; > > u64 rx_err_oflow; > > u64 rx_err_ver; > > + u64 rx_memcpy; > > + u64 rx_async; > > u64 tx_bytes; > > u64 tx_pkts; > > u64 tx_ring_full; > > + u64 tx_err_no_buf; > > + u64 tx_memcpy; > > + u64 tx_async; > > }; > > > > struct ntb_transport_mw { > > @@ -381,7 +401,7 @@ static ssize_t debugfs_read(struct file *filp, char __user *ubuf, size_t count, > > char *buf; > > ssize_t ret, out_offset, out_count; > > > > - out_count = 600; > > + out_count = 1000; > > > > buf = kmalloc(out_count, GFP_KERNEL); > > if (!buf) > > @@ -396,6 +416,10 @@ static ssize_t debugfs_read(struct file *filp, char __user *ubuf, size_t count, > > out_offset += snprintf(buf + out_offset, out_count - out_offset, > > "rx_pkts - \t%llu\n", qp->rx_pkts); > > out_offset += snprintf(buf + out_offset, out_count - out_offset, > > + "rx_memcpy - \t%llu\n", qp->rx_memcpy); > > + out_offset += snprintf(buf + out_offset, out_count - out_offset, > > + "rx_async - \t%llu\n", qp->rx_async); > > + out_offset += snprintf(buf + out_offset, out_count - out_offset, > > "rx_ring_empty - %llu\n", qp->rx_ring_empty); > > out_offset += snprintf(buf + out_offset, out_count - out_offset, > > "rx_err_no_buf - %llu\n", qp->rx_err_no_buf); > > @@ -415,8 +439,14 @@ static ssize_t debugfs_read(struct file *filp, char __user *ubuf, size_t count, > > out_offset += snprintf(buf + out_offset, out_count - out_offset, > > "tx_pkts - \t%llu\n", qp->tx_pkts); > > out_offset += snprintf(buf + out_offset, out_count - out_offset, > > + "tx_memcpy - \t%llu\n", qp->tx_memcpy); > > + out_offset += snprintf(buf + out_offset, out_count - out_offset, > > + "tx_async - \t%llu\n", qp->tx_async); > > + out_offset += snprintf(buf + out_offset, out_count - out_offset, > > "tx_ring_full - \t%llu\n", qp->tx_ring_full); > > out_offset += snprintf(buf + out_offset, out_count - out_offset, > > + "tx_err_no_buf - %llu\n", qp->tx_err_no_buf); > > + out_offset += snprintf(buf + out_offset, out_count - out_offset, > > "tx_mw - \t%p\n", qp->tx_mw); > > out_offset += snprintf(buf + out_offset, out_count - out_offset, > > "tx_index - \t%u\n", qp->tx_index); > > @@ -488,11 +518,11 @@ static void ntb_transport_setup_qp_mw(struct ntb_transport *nt, > > num_qps_mw = nt->max_qps / mw_max; > > > > rx_size = (unsigned int) nt->mw[mw_num].size / num_qps_mw; > > - qp->remote_rx_info = nt->mw[mw_num].virt_addr + > > - (qp_num / mw_max * rx_size); > > + qp->rx_buff = nt->mw[mw_num].virt_addr + qp_num / mw_max * rx_size; > > rx_size -= sizeof(struct ntb_rx_info); > > > > - qp->rx_buff = qp->remote_rx_info + 1; > > + qp->remote_rx_info = qp->rx_buff + rx_size; > > + > > /* Due to housekeeping, there must be atleast 2 buffs */ > > qp->rx_max_frame = min(transport_mtu, rx_size / 2); > > qp->rx_max_entry = rx_size / qp->rx_max_frame; > > @@ -802,6 +832,7 @@ static void ntb_transport_init_queue(struct ntb_transport *nt, > > struct ntb_transport_qp *qp; > > unsigned int num_qps_mw, tx_size; > > u8 mw_num, mw_max; > > + u64 qp_offset; > > > > mw_max = ntb_max_mw(nt->ndev); > > mw_num = QP_TO_MW(nt->ndev, qp_num); > > @@ -820,11 +851,12 @@ static void ntb_transport_init_queue(struct ntb_transport *nt, > > num_qps_mw = nt->max_qps / mw_max; > > > > tx_size = (unsigned int) ntb_get_mw_size(qp->ndev, mw_num) / num_qps_mw; > > - qp->rx_info = ntb_get_mw_vbase(nt->ndev, mw_num) + > > - (qp_num / mw_max * tx_size); > > + qp_offset = qp_num / mw_max * tx_size; > > + qp->tx_mw = ntb_get_mw_vbase(nt->ndev, mw_num) + qp_offset; > > + qp->tx_mw_raw = ntb_get_mw_base(qp->ndev, mw_num) + qp_offset; > > Just a quibble with the name, why "raw" instead of "phys"? What's in a name? ;-) phys is fine. > > > tx_size -= sizeof(struct ntb_rx_info); > > + qp->rx_info = qp->tx_mw + tx_size; > > > > - qp->tx_mw = qp->rx_info + 1; > > /* Due to housekeeping, there must be atleast 2 buffs */ > > qp->tx_max_frame = min(transport_mtu, tx_size / 2); > > qp->tx_max_entry = tx_size / qp->tx_max_frame; > > @@ -956,13 +988,22 @@ void ntb_transport_free(void *transport) > > kfree(nt); > > } > > > > -static void ntb_rx_copy_task(struct ntb_transport_qp *qp, > > - struct ntb_queue_entry *entry, void *offset) > > +static void ntb_rx_copy_callback(void *data) > > { > > + struct ntb_queue_entry *entry = data; > > + struct ntb_transport_qp *qp = entry->qp; > > void *cb_data = entry->cb_data; > > unsigned int len = entry->len; > > + struct ntb_payload_header *hdr = entry->rx_hdr; > > + > > + wmb(); > > What is this barrier paired with? You will see a wmb being removed from ntb_process_rxc below. It is VERY necessary to be here. > > + hdr->flags = 0; > > > > - memcpy(entry->buf, offset, entry->len); > > + /* If the callbacks come out of order, the writing of the index to the > > + * last completed will be out of order. This may result in the the > > + * receive stalling forever. > > + */ > > Is this for the case where we are bouncing back and forth between > sync/async? Otherwise I do not see how transactions could get out of > order given you allocate a channel once per queue. Is this comment > saying that the iowrite32 is somehow a fix, or is this comment a > FIXME? There is a case for a mix, the "copy_bytes" variable above switches to CPU for small transfers (which greatly increases throughput on small transfers). The caveat to it is the need to flush the DMA engine to prevent out-of-order. This comment is mainly an reminder of this issue. > > + iowrite32(entry->index, &qp->rx_info->entry); > > > > ntb_list_add(&qp->ntb_rx_free_q_lock, &entry->entry, &qp->rx_free_q); > > > > @@ -970,6 +1011,80 @@ static void ntb_rx_copy_task(struct ntb_transport_qp *qp, > > qp->rx_handler(qp, qp->cb_data, cb_data, len); > > } > > > > +static void ntb_memcpy_rx(struct ntb_queue_entry *entry, void *offset) > > +{ > > + void *buf = entry->buf; > > + size_t len = entry->len; > > + > > + memcpy(buf, offset, len); > > + > > + ntb_rx_copy_callback(entry); > > +} > > + > > +static void ntb_async_rx(struct ntb_queue_entry *entry, void *offset, > > + size_t len) > > +{ > > + struct dma_async_tx_descriptor *txd; > > + struct ntb_transport_qp *qp = entry->qp; > > + struct dma_chan *chan = qp->dma_chan; > > + struct dma_device *device; > > + dma_addr_t src, dest; > > + dma_cookie_t cookie; > > + void *buf = entry->buf; > > + unsigned long flags; > > + > > + entry->len = len; > > + > > + if (!chan) > > + goto err; > > + > > + device = chan->device; > > + > > + if (len < copy_bytes || > > + !is_dma_copy_aligned(device, __pa(offset), __pa(buf), len)) > > __pa()'s necessary here? I don't think the alignment requirements > will ever cross PAGE_OFFSET. The __pa calls cast the void* to an unsigned long, thus keeping is_dma_copy_aligned happy. > > + goto err1; > > + > > + dest = dma_map_single(device->dev, buf, len, DMA_FROM_DEVICE); > > + if (dma_mapping_error(device->dev, dest)) > > + goto err1; > > + > > + src = dma_map_single(device->dev, offset, len, DMA_TO_DEVICE); > > + if (dma_mapping_error(device->dev, src)) > > + goto err2; > > + > > + flags = DMA_COMPL_DEST_UNMAP_SINGLE | DMA_COMPL_SRC_UNMAP_SINGLE | > > + DMA_PREP_INTERRUPT; > > + txd = device->device_prep_dma_memcpy(chan, dest, src, len, flags); > > + if (!txd) > > + goto err3; > > + > > + txd_clear_parent(txd); > > + txd_clear_next(txd); > > Neither of these should be necessary. I had crashes in early versions of the code without them, but a quick test with the removed doesn't show any issues. Good catch. > > + txd->callback = ntb_rx_copy_callback; > > + txd->callback_param = entry; > > + > > + cookie = dmaengine_submit(txd); > > + if (dma_submit_error(cookie)) > > + goto err3; > > + > > + qp->last_cookie = cookie; > > + > > + dma_async_issue_pending(chan); > > hmm... can this go in ntb_process_rx() so that the submission is > batched? Cuts down on mmio. I moved it down to ntb_transport_rx (after the calls to ntb_process_rxc), and the performance seems to be roughly the same. > > + qp->rx_async++; > > + > > + return; > > + > > +err3: > > + dma_unmap_single(device->dev, src, len, DMA_TO_DEVICE); > > +err2: > > + dma_unmap_single(device->dev, dest, len, DMA_FROM_DEVICE); > > +err1: > > + dma_sync_wait(chan, qp->last_cookie); > > +err: > > + ntb_memcpy_rx(entry, offset); > > + qp->rx_memcpy++; > > +} > > + > > static int ntb_process_rxc(struct ntb_transport_qp *qp) > > { > > struct ntb_payload_header *hdr; > > @@ -1008,41 +1123,44 @@ static int ntb_process_rxc(struct ntb_transport_qp *qp) > > if (hdr->flags & LINK_DOWN_FLAG) { > > ntb_qp_link_down(qp); > > > > - ntb_list_add(&qp->ntb_rx_pend_q_lock, &entry->entry, > > - &qp->rx_pend_q); > > - goto out; > > + goto err; > > } > > > > dev_dbg(&ntb_query_pdev(qp->ndev)->dev, > > "rx offset %u, ver %u - %d payload received, buf size %d\n", > > qp->rx_index, hdr->ver, hdr->len, entry->len); > > > > - if (hdr->len <= entry->len) { > > - entry->len = hdr->len; > > - ntb_rx_copy_task(qp, entry, offset); > > - } else { > > - ntb_list_add(&qp->ntb_rx_pend_q_lock, &entry->entry, > > - &qp->rx_pend_q); > > + qp->rx_bytes += hdr->len; > > + qp->rx_pkts++; > > > > + if (hdr->len > entry->len) { > > qp->rx_err_oflow++; > > dev_dbg(&ntb_query_pdev(qp->ndev)->dev, > > "RX overflow! Wanted %d got %d\n", > > hdr->len, entry->len); > > + > > + goto err; > > } > > > > - qp->rx_bytes += hdr->len; > > - qp->rx_pkts++; > > + entry->index = qp->rx_index; > > + entry->rx_hdr = hdr; > > > > -out: > > - /* Ensure that the data is fully copied out before clearing the flag */ > > - wmb(); > > - hdr->flags = 0; > > - iowrite32(qp->rx_index, &qp->rx_info->entry); > > + ntb_async_rx(entry, offset, hdr->len); > > > > +out: > > qp->rx_index++; > > qp->rx_index %= qp->rx_max_entry; > > > > return 0; > > + > > +err: > > + ntb_list_add(&qp->ntb_rx_pend_q_lock, &entry->entry, > > + &qp->rx_pend_q); > > + wmb(); > > + hdr->flags = 0; > > + iowrite32(qp->rx_index, &qp->rx_info->entry); > > + > > + goto out; > > } > > > > static void ntb_transport_rx(unsigned long data) > > @@ -1070,19 +1188,12 @@ static void ntb_transport_rxc_db(void *data, int db_num) > > tasklet_schedule(&qp->rx_work); > > } > > > > -static void ntb_tx_copy_task(struct ntb_transport_qp *qp, > > - struct ntb_queue_entry *entry, > > - void __iomem *offset) > > +static void ntb_tx_copy_callback(void *data) > > { > > - struct ntb_payload_header __iomem *hdr; > > - > > - memcpy_toio(offset, entry->buf, entry->len); > > - > > - hdr = offset + qp->tx_max_frame - sizeof(struct ntb_payload_header); > > - iowrite32(entry->len, &hdr->len); > > - iowrite32((u32) qp->tx_pkts, &hdr->ver); > > + struct ntb_queue_entry *entry = data; > > + struct ntb_transport_qp *qp = entry->qp; > > + struct ntb_payload_header __iomem *hdr = entry->tx_hdr; > > > > - /* Ensure that the data is fully copied out before setting the flag */ > > wmb(); > > iowrite32(entry->flags | DESC_DONE_FLAG, &hdr->flags); > > > > @@ -1103,15 +1214,79 @@ static void ntb_tx_copy_task(struct ntb_transport_qp *qp, > > ntb_list_add(&qp->ntb_tx_free_q_lock, &entry->entry, &qp->tx_free_q); > > } > > > > -static int ntb_process_tx(struct ntb_transport_qp *qp, > > - struct ntb_queue_entry *entry) > > +static void ntb_memcpy_tx(struct ntb_queue_entry *entry, void __iomem *offset) > > +{ > > + memcpy_toio(offset, entry->buf, entry->len); > > + > > + ntb_tx_copy_callback(entry); > > +} > > + > > +static void ntb_async_tx(struct ntb_transport_qp *qp, > > + struct ntb_queue_entry *entry) > > { > > + struct dma_async_tx_descriptor *txd; > > + struct dma_chan *chan = qp->dma_chan; > > + struct dma_device *device; > > + dma_addr_t src, dest; > > + dma_cookie_t cookie; > > + struct ntb_payload_header __iomem *hdr; > > void __iomem *offset; > > + size_t len = entry->len; > > + void *buf = entry->buf; > > + unsigned long flags; > > > > offset = qp->tx_mw + qp->tx_max_frame * qp->tx_index; > > + hdr = offset + qp->tx_max_frame - sizeof(struct ntb_payload_header); > > + entry->tx_hdr = hdr; > > + > > + iowrite32(entry->len, &hdr->len); > > + iowrite32((u32) qp->tx_pkts, &hdr->ver); > > + > > + if (!chan) > > + goto err; > > > > - dev_dbg(&ntb_query_pdev(qp->ndev)->dev, "%lld - offset %p, tx %u, entry len %d flags %x buff %p\n", > > - qp->tx_pkts, offset, qp->tx_index, entry->len, entry->flags, > > + device = chan->device; > > + > > + dest = qp->tx_mw_raw + qp->tx_max_frame * qp->tx_index; > > + > > + if (len < copy_bytes || > > + !is_dma_copy_aligned(device, __pa(buf), dest, len)) > > ditto on the use of __pa here. > > > + goto err; > > + > > + src = dma_map_single(device->dev, buf, len, DMA_TO_DEVICE); > > + if (dma_mapping_error(device->dev, src)) > > + goto err; > > + > > + flags = DMA_COMPL_SRC_UNMAP_SINGLE | DMA_PREP_INTERRUPT; > > + txd = device->device_prep_dma_memcpy(chan, dest, src, len, flags); > > + if (!txd) > > + goto err1; > > + > > + txd_clear_parent(txd); > > + txd_clear_next(txd); > > ...again not needed. > > > + txd->callback = ntb_tx_copy_callback; > > + txd->callback_param = entry; > > + > > + cookie = dmaengine_submit(txd); > > + if (dma_submit_error(cookie)) > > + goto err1; > > + > > + dma_async_issue_pending(chan); > > + qp->tx_async++; > > + > > + return; > > +err1: > > + dma_unmap_single(device->dev, src, len, DMA_TO_DEVICE); > > +err: > > + ntb_memcpy_tx(entry, offset); > > + qp->tx_memcpy++; > > +} > > + > > +static int ntb_process_tx(struct ntb_transport_qp *qp, > > + struct ntb_queue_entry *entry) > > +{ > > + dev_dbg(&ntb_query_pdev(qp->ndev)->dev, "%lld - tx %u, entry len %d flags %x buff %p\n", > > + qp->tx_pkts, qp->tx_index, entry->len, entry->flags, > > entry->buf); > > if (qp->tx_index == qp->remote_rx_info->entry) { > > qp->tx_ring_full++; > > @@ -1127,7 +1302,7 @@ static int ntb_process_tx(struct ntb_transport_qp *qp, > > return 0; > > } > > > > - ntb_tx_copy_task(qp, entry, offset); > > + ntb_async_tx(qp, entry); > > > > qp->tx_index++; > > qp->tx_index %= qp->tx_max_entry; > > @@ -1213,11 +1388,16 @@ ntb_transport_create_queue(void *data, struct pci_dev *pdev, > > qp->tx_handler = handlers->tx_handler; > > qp->event_handler = handlers->event_handler; > > > > + qp->dma_chan = dma_find_channel(DMA_MEMCPY); > > + if (!qp->dma_chan) > > + dev_info(&pdev->dev, "Unable to allocate private DMA channel, using CPU instead\n"); > > You can drop "private" since this is a public allocation. Good catch > > + > > for (i = 0; i < NTB_QP_DEF_NUM_ENTRIES; i++) { > > entry = kzalloc(sizeof(struct ntb_queue_entry), GFP_ATOMIC); > > if (!entry) > > goto err1; > > > > + entry->qp = qp; > > ntb_list_add(&qp->ntb_rx_free_q_lock, &entry->entry, > > &qp->rx_free_q); > > } > > @@ -1227,6 +1407,7 @@ ntb_transport_create_queue(void *data, struct pci_dev *pdev, > > if (!entry) > > goto err2; > > > > + entry->qp = qp; > > ntb_list_add(&qp->ntb_tx_free_q_lock, &entry->entry, > > &qp->tx_free_q); > > } > > @@ -1272,11 +1453,14 @@ void ntb_transport_free_queue(struct ntb_transport_qp *qp) > > > > pdev = ntb_query_pdev(qp->ndev); > > > > - cancel_delayed_work_sync(&qp->link_work); > > + if (qp->dma_chan) > > + dmaengine_terminate_all(qp->dma_chan); > > Do you need this or can you just wait for all outstanding tx / rx to quiesce? I'd prefer not to spin in the shutdown code waiting for the channel to quiesce. I suppose I could be nice and give it a small time to do so, before I smash it in the head with a rock. > > ntb_unregister_db_callback(qp->ndev, qp->qp_num); > > tasklet_disable(&qp->rx_work); > > > > + cancel_delayed_work_sync(&qp->link_work); > > + > > while ((entry = ntb_list_rm(&qp->ntb_rx_free_q_lock, &qp->rx_free_q))) > > kfree(entry); > > > > @@ -1382,8 +1566,10 @@ int ntb_transport_tx_enqueue(struct ntb_transport_qp *qp, void *cb, void *data, > > return -EINVAL; > > > > entry = ntb_list_rm(&qp->ntb_tx_free_q_lock, &qp->tx_free_q); > > - if (!entry) > > + if (!entry) { > > + qp->tx_err_no_buf++; > > return -ENOMEM; > > + } > > > > entry->cb_data = cb; > > entry->buf = data; > > @@ -1499,9 +1685,18 @@ EXPORT_SYMBOL_GPL(ntb_transport_qp_num); > > */ > > unsigned int ntb_transport_max_size(struct ntb_transport_qp *qp) > > { > > + unsigned int max; > > + > > if (!qp) > > return 0; > > > > - return qp->tx_max_frame - sizeof(struct ntb_payload_header); > > + if (!qp->dma_chan) > > + return qp->tx_max_frame - sizeof(struct ntb_payload_header); > > + > > + /* If DMA engine usage is possible, try to find the max size for that */ > > + max = qp->tx_max_frame - sizeof(struct ntb_payload_header); > > + max -= max % (1 << qp->dma_chan->device->copy_align); > > Unless I missed it you need a dmaengine_get() dmaengine_put() pair in > your driver setup/teardown. dmaengine_get() notifies dmaengine of a > dma_find_channel() user. Good catch. Thanks for the review! I'll make the changes and do another spin of the patch. Thanks, Jon -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/