Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751823Ab3HTAHs (ORCPT ); Mon, 19 Aug 2013 20:07:48 -0400 Received: from mga09.intel.com ([134.134.136.24]:56878 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751728Ab3HTAHr (ORCPT ); Mon, 19 Aug 2013 20:07:47 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.89,915,1367996400"; d="scan'208";a="389816304" Date: Mon, 19 Aug 2013 17:07:35 -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: <20130820000734.GD22169@jonmason-lab> References: <20130819203730.GB22169@jonmason-lab> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit 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: 28675 Lines: 787 On Mon, Aug 19, 2013 at 11:36:13PM +0000, Dan Williams wrote: > > > On 8/19/13 1:37 PM, "Jon Mason" wrote: > > >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)); > >> > +} > > Nothing does error checking on this return value. I think the code should > either be sure that Œmw' is valid (mw_num is passed to the > ntb_get_mw_vbase helper too) and delete the check, or at least make it a > WARN_ONCE. The former seems a tad cleaner to me. Ugh! Thanks. > > > >> > + > >> > +/** > >> > * 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. > > If it¹s not paired with a read barrier it needs a comment about what it is > ordering. I thought checkpatch would squawk about this? I¹m curious why > not a full read back to verify the write completes vs mmiowb()? wmb() is > somewhere in the middle. I'm pretty sure I ran all this through checkpatch before sending. I'll re-add the comment I had before. > > > > >> > + 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. > > So this is going forward with the stall as a known issue? The next patch > should just do the sync to prevent the re-ordering, right? There is already a dma_sync_wait in the error path of ntb_async_rx to enforce the ordering. Do I need to change the comment (or move it) to make it more obvious what is happening? > > > >> > + 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. > > Then "(unsigned long) offset, (unsigned long) buf² right? Why munge the > value? Fair enough. > > > > >> > + 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. > > Yeah, not expecting it to be noticeable, but conceptually > > submit > submit > submit > submit > issue > > > Is nicer than: > > submit > issue > submit > issue > > I agree, but I liked having all the dma engine awareness compartmentalized in the ntb_async_* and callbacks. > > > > > > >> > + 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. > > But ->device_control is not a mandatory operation. You¹re already sync > waiting for the workqueue to die. I added it and I do think it will be a little nicer Thanks, Jon > > > > >> > 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/