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Subject[PATCH 3 of 20] ipath - copy and send routines for sending an skb
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Signed-off-by: Bryan O'Sullivan <bos@pathscale.com>

diff -r 19bdf20bc544 -r 227b3e7c27ce drivers/infiniband/hw/ipath/ipath_copy.c
--- /dev/null Thu Jan 1 00:00:00 1970 +0000
+++ b/drivers/infiniband/hw/ipath/ipath_copy.c Thu Mar 9 16:15:23 2006 -0800
@@ -0,0 +1,504 @@
+/*
+ * Copyright (c) 2003, 2004, 2005, 2006 PathScale, Inc. All rights reserved.
+ *
+ * This software is available to you under a choice of one of two
+ * licenses. You may choose to be licensed under the terms of the GNU
+ * General Public License (GPL) Version 2, available from the file
+ * COPYING in the main directory of this source tree, or the
+ * OpenIB.org BSD license below:
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * - Redistributions of source code must retain the above
+ * copyright notice, this list of conditions and the following
+ * disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following
+ * disclaimer in the documentation and/or other materials
+ * provided with the distribution.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+/*
+ * This file provides support for doing sk_buff buffer swapping between
+ * the low level driver eager buffers, and the network layer. It's part
+ * of the core driver, rather than the ether driver, because it relies
+ * on variables and functions in the core driver. It exports a single
+ * entry point for use in the ipath_ether module.
+ */
+
+#include <linux/io.h>
+#include <linux/pci.h>
+#include <linux/netdevice.h>
+
+#include "ipath_kernel.h"
+#include "ips_common.h"
+
+/**
+ * layer_send_getpiobuf - allocate, setup and copy out a PIO send buffer
+ * @dd: the infinipath device
+ * @cdp: the data to copy
+ *
+ * Allocate a PIO send buffer, initialize the header and copy it out.
+ */
+static int layer_send_getpiobuf(struct ipath_devdata *dd,
+ struct copy_data_s *cdp)
+{
+ u32 extra_bytes;
+ u32 len, nwords, hdrwords;
+ u32 __iomem *piobuf;
+
+ piobuf = ipath_getpiobuf(dd, NULL);
+ if (!piobuf) {
+ cdp->error = -EBUSY;
+ return cdp->error;
+ }
+
+ /*
+ * Compute the max amount of data that can fit into a PIO buffer.
+ * buffer size - header size - trigger qword length & flags - CRC
+ */
+ len = dd->ipath_ibmaxlen -
+ sizeof(struct ether_header) - 8 - (SIZE_OF_CRC << 2);
+ if (len > dd->ipath_rcvegrbufsize)
+ len = dd->ipath_rcvegrbufsize;
+ if (len > (cdp->len + cdp->extra))
+ len = (cdp->len + cdp->extra);
+ /* Compute word aligment (i.e., (len & 3) ? 4 - (len & 3) : 0) */
+ extra_bytes = (4 - len) & 3;
+ nwords = (sizeof(struct ether_header) + len + extra_bytes) >> 2;
+ cdp->hdr->lrh[2] = htons(nwords + SIZE_OF_CRC);
+ cdp->hdr->bth[0] = htonl((OPCODE_ITH4X << 24) +
+ (extra_bytes << 20) +
+ IPS_DEFAULT_P_KEY);
+ cdp->hdr->sub_opcode = OPCODE_ENCAP;
+
+ cdp->hdr->bth[2] = 0;
+ /*
+ * Generate an interrupt on the receive side for the last
+ * fragment.
+ */
+ cdp->hdr->iph.pkt_flags = ((cdp->len + cdp->extra) == len)
+ ? INFINIPATH_KPF_INTR : 0;
+ cdp->hdr->iph.chksum =
+ (u16) IPS_LRH_BTH + (u16) (nwords + SIZE_OF_CRC) -
+ (u16) ((cdp->hdr->iph.ver_port_tid_offset >> 16) & 0xFFFF) -
+ (u16) (cdp->hdr->iph.ver_port_tid_offset & 0xFFFF) -
+ (u16) cdp->hdr->iph.pkt_flags;
+
+ ipath_cdbg(VERBOSE, "send %d (%x %x %x %x %x %x %x)\n", nwords,
+ cdp->hdr->lrh[0], cdp->hdr->lrh[1],
+ cdp->hdr->lrh[2], cdp->hdr->lrh[3],
+ cdp->hdr->bth[0], cdp->hdr->bth[1], cdp->hdr->bth[2]);
+ /*
+ * Write len to control qword, no flags.
+ * +1 is for the qword padding of pbc.
+ */
+ writeq(nwords + 1ULL, (u64 __iomem *) piobuf);
+ /* we have to flush after the PBC for correctness on some cpus
+ * or WC buffer can be written out of order */
+ ipath_flush_wc();
+ piobuf += 2;
+ hdrwords = sizeof(struct ether_header) >> 2;
+ __iowrite32_copy(piobuf, cdp->hdr, hdrwords);
+ cdp->csum_pio = &((struct ether_header __iomem *)piobuf)->csum;
+ cdp->to = piobuf + hdrwords;
+ cdp->flen = nwords - hdrwords;
+ cdp->hdr->frag_num++;
+ return 0;
+}
+
+/**
+ * copy_extra_dword - copy the last full dword
+ * @dd: the infinipath device
+ * @cdp: the data to copy
+ * @dosum: write a checksum if true
+ *
+ * copy the last full dword when that's the "extra" word, preceding it
+ * with a memory fence, so that all prior data is written to the PIO
+ * buffer before the trigger word, to enforce the correct bus ordering
+ * of the WC buffer contents on the bus.
+ */
+static inline unsigned copy_extra_dword(struct ipath_devdata *dd,
+ struct copy_data_s *cdp,
+ unsigned dosum)
+{
+ if (!cdp->flen && layer_send_getpiobuf(dd, cdp) < 0)
+ return 1;
+ /* write the checksum before the last PIO write, if requested. */
+ if (dosum && cdp->flen == 1)
+ __raw_writel(csum_fold(cdp->csum), cdp->csum_pio);
+ cdp->extra = 0;
+ cdp->flen -= 1;
+ if (!cdp->flen) { /* trigger word being written */
+ ipath_flush_wc();
+ __raw_writel(cdp->u.w, cdp->to++);
+ ipath_flush_wc();
+ } else /* still more to copy to pio buf */
+ __raw_writel(cdp->u.w, cdp->to++);
+ return 0;
+}
+
+/**
+ * copy_a_buffer - copy a PIO buffer's worth to the PIO buffer
+ * @dd: the infinipath device
+ * @cdp: the destination
+ * @p: the data to copy
+ * @n: the amount to copy
+ * @dosum: write a checksum if true
+ *
+ * copy a PIO buffer's worth (or the skb fragment, at least) to the PIO
+ * buffer, adding a memory fence before the last word. We need the fence
+ * as part of forcing the WC ordering on some cpus, for the cases where
+ * it will be the trigger word. The final fence after the trigger word
+ * will be done either at the next chunk, or on final return from the caller
+ * Takes max byte count, returns byte count actually done (always rounded
+ * to dword multiple).
+ */
+static u32 copy_a_buffer(struct ipath_devdata *dd, struct copy_data_s *cdp,
+ void *p, u32 n, unsigned dosum)
+{
+ u32 *p32;
+
+ if (!cdp->flen && layer_send_getpiobuf(dd, cdp) < 0)
+ return -1;
+ if (n > cdp->flen)
+ n = cdp->flen;
+ if (dosum && cdp->flen == n)
+ __raw_writel(csum_fold(cdp->csum), cdp->csum_pio);
+ p32 = p;
+ cdp->flen -= n;
+ if (!cdp->flen) { /* trigger word being written */
+ __iowrite32_copy(cdp->to, p32, n - 1);
+ cdp->to += n - 1;
+ ipath_flush_wc();
+ __raw_writel(p32[n - 1], cdp->to++);
+ ipath_flush_wc();
+ } else { /* still more to copy to pio buf */
+ __iowrite32_copy(cdp->to, p32, n);
+ cdp->to += n;
+ }
+ n <<= 2;
+ cdp->offset += n;
+ cdp->len -= n;
+ return n;
+}
+
+static inline int copy_bits_internal(struct ipath_devdata *dd,
+ struct copy_data_s *cdp, u8 *p,
+ unsigned *copyp, unsigned *offsetp,
+ unsigned *lenp, int do_csum)
+{
+ unsigned copy = *copyp;
+ unsigned len = *lenp;
+ int ret = 1;
+
+ if (copy > len)
+ copy = len;
+ *offsetp += copy;
+ len -= copy;
+ if (do_csum && !cdp->checksum_calc) {
+ unsigned int csum2;
+
+ cdp->checksum_calc = 1;
+
+ csum2 = csum_partial(p, copy, 0);
+ cdp->csum = csum_block_add(cdp->csum, csum2, cdp->pos);
+ cdp->pos += copy;
+ }
+ /*
+ * If the alignment buffer is not empty, fill it and write it
+ * out.
+ */
+ if (cdp->extra) {
+ if (cdp->extra == 4) {
+ if (copy_extra_dword(dd, cdp, 1))
+ goto done;
+ }
+ else while (copy != 0) {
+ cdp->u.buf[cdp->extra] = *p++;
+ copy--;
+ cdp->offset++;
+ cdp->len--;
+ if (++cdp->extra == 4) {
+ if (copy_extra_dword(dd, cdp, 1))
+ goto done;
+ break;
+ }
+ }
+ }
+
+ while (copy >= 4) {
+ u32 n = copy_a_buffer(dd, cdp, p, copy >> 2, 1);
+ if (n == -1)
+ goto done;
+ p += n;
+ copy -= n;
+ }
+ /*
+ * Either cdp->extra is zero or copy is zero, which means that
+ * the loop here can't cause the alignment buffer to fill up.
+ */
+ while (copy != 0) {
+ cdp->u.buf[cdp->extra++] = *p++;
+ copy--;
+ cdp->offset++;
+ cdp->len--;
+ }
+
+ if (do_csum)
+ cdp->checksum_calc = 0;
+
+ if (len == 0)
+ goto done;
+
+ ret = 0;
+done:
+ *copyp = copy;
+ *lenp = len;
+ return ret;
+}
+
+/**
+ * copy_and_maybe_csum_bits - copy data into the PIO buffer
+ * @dd: the infinipath device
+ * @skb: the source sk_buff
+ * @offset: the offset within the source
+ * @len: the len of the data to copy
+ * @cdp: the destination
+ * @do_csum: write a checksum if true
+ *
+ * Copy data out of one or a chain of sk_buffs, into the PIO buffer,
+ * generating the checksum as we go if do_csum is non-zero.
+ * Fragment an sk_buff into multiple IB packets if the amount of data
+ * is more than a single eager send.
+ * Offset and len are in bytes.
+ * Note that this function is recursive!
+ */
+static void copy_and_maybe_csum_bits(struct ipath_devdata *dd,
+ const struct sk_buff *skb,
+ unsigned int offset,
+ unsigned int len,
+ struct copy_data_s *cdp,
+ int do_csum)
+{
+ unsigned int start = skb_headlen(skb);
+ unsigned int i, copy;
+
+ /* Copy header. */
+ copy = start - offset;
+ if ((int) copy > 0) {
+ u8 *p = skb->data + offset;
+
+ if (copy_bits_internal(dd, cdp, p, &copy, &offset, &len,
+ do_csum))
+ goto done;
+ }
+
+ for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+ skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
+ unsigned int end;
+
+ end = start + frag->size;
+ copy = end - offset;
+ if ((int) copy > 0) {
+ u8 *vaddr = kmap_skb_frag(frag);
+ u8 *p = vaddr + frag->page_offset + offset - start;
+ int ret;
+
+ ret = copy_bits_internal(dd, cdp, p, &copy,
+ &offset, &len, do_csum);
+
+ kunmap_skb_frag(vaddr);
+
+ if (ret)
+ goto done;
+ }
+ start = end;
+ }
+
+ if (skb_shinfo(skb)->frag_list) {
+ struct sk_buff *list = skb_shinfo(skb)->frag_list;
+
+ for (; list; list = list->next) {
+ unsigned int end;
+
+ end = start + list->len;
+ copy = end - offset;
+ if ((int) copy > 0) {
+ if (copy > len)
+ copy = len;
+ copy_and_maybe_csum_bits(dd, list,
+ offset - start,
+ copy, cdp,
+ do_csum);
+ len -= copy;
+ if (cdp->error || len == 0)
+ goto done;
+ offset += copy;
+ }
+ start = end;
+ }
+ }
+ if (len)
+ cdp->error = -EFAULT;
+done:
+ /* we have to flush after trigger word for correctness on some
+ * cpus or WC buffer can be written out of order; needed even
+ * if there was an error */
+ ipath_flush_wc();
+}
+
+static inline void copy_and_csum_bits(struct ipath_devdata *dd,
+ const struct sk_buff *skb,
+ unsigned int offset,
+ unsigned int len,
+ struct copy_data_s *cdp)
+{
+ copy_and_maybe_csum_bits(dd, skb, offset, len, cdp, 1);
+}
+
+static inline void copy_bits(struct ipath_devdata *dd,
+ const struct sk_buff *skb,
+ unsigned int offset,
+ unsigned int len,
+ struct copy_data_s *cdp)
+{
+ copy_and_maybe_csum_bits(dd, skb, offset, len, cdp, 0);
+}
+
+/**
+ * ipath_layer_send_skb - layered sk_buff send
+ * @dd: the infinipath device
+ * @cdata: the data to send
+ *
+ * This is called by the ipath_ether module.
+ *
+ * Note that the header should have the unchanging parts
+ * initialized but the rest of the header is computed as needed in
+ * order to break up skb data buffers larger than the hardware MTU.
+ * In other words, the Linux network stack MTU can be larger than the
+ * hardware MTU.
+ */
+int ipath_layer_send_skb(struct ipath_devdata *dd,
+ struct copy_data_s *cdata)
+{
+ int ret = 0;
+ u16 vlsllnh;
+
+ if (!(dd->ipath_flags & IPATH_RCVHDRSZ_SET)) {
+ dev_info(&dd->pcidev->dev, "send while not open\n");
+ ret = -EINVAL;
+ }
+ else if ((dd->ipath_flags & (IPATH_LINKUNK | IPATH_LINKDOWN)) ||
+ dd->ipath_lid == 0) {
+ /* lid check is for when sma hasn't yet configured */
+ ret = -ENETDOWN;
+ ipath_cdbg(VERBOSE, "send while not ready, mylid=%u, "
+ "flags=0x%x\n", dd->ipath_lid, dd->ipath_flags);
+ }
+ vlsllnh = *((u16 *) cdata->hdr);
+ if (vlsllnh != htons(IPS_LRH_BTH)) {
+ ipath_dbg("Warning: lrh[0] wrong (%x, not %x); "
+ "not sending\n", vlsllnh, htons(IPS_LRH_BTH));
+ ret = -EINVAL;
+ }
+ if (ret)
+ goto done;
+
+ cdata->error = 0; /* clear last calls error */
+
+ if (cdata->skb->ip_summed == CHECKSUM_HW) {
+ unsigned int csstart = cdata->skb->h.raw - cdata->skb->data;
+
+ /*
+ * Computing the checksum is a bit tricky since if we
+ * fragment the packet, the fragment that should contain the
+ * checksum will have already been sent. The solution is to
+ * store the checksum in the header of the last fragment
+ * just before we write the last data word which triggers
+ * the last fragment to be sent. The receiver will check
+ * the header "tag" field, see that there is a checksum, and
+ * store the checksum back into the packet.
+ *
+ * Save the offset of the two byte checksum.
+ *
+ * Note that we have to add 2 to account for the two bytes
+ * of the ethernet address we stripped from the packet and
+ * put in the header.
+ */
+
+ cdata->hdr->csum_offset = csstart + cdata->skb->csum + 2;
+
+ if (cdata->offset < csstart)
+ copy_bits(dd, cdata->skb, cdata->offset,
+ csstart - cdata->offset, cdata);
+
+ if (cdata->error) {
+ ret = cdata->error;
+ goto done;
+ }
+
+ if (cdata->offset < cdata->skb->len)
+ copy_and_csum_bits(dd, cdata->skb, cdata->offset,
+ cdata->skb->len - cdata->offset,
+ cdata);
+
+ if (cdata->error) {
+ ret = cdata->error;
+ goto done;
+ }
+
+ if (cdata->extra) {
+ while (cdata->extra < 4)
+ cdata->u.buf[cdata->extra++] = 0;
+ (void)copy_extra_dword(dd, cdata, 1);
+ }
+ } else {
+ copy_bits(dd, cdata->skb, cdata->offset,
+ cdata->skb->len - cdata->offset, cdata);
+
+ if (cdata->error) {
+ ret = cdata->error;
+ goto done;
+ }
+
+ if (cdata->extra) {
+ while (cdata->extra < 4)
+ cdata->u.buf[cdata->extra++] = 0;
+ (void)copy_extra_dword(dd, cdata, 1);
+ }
+ }
+
+ if (cdata->error) {
+ ret = cdata->error;
+ if (cdata->error != -EBUSY)
+ ipath_dev_err(dd, "layer_send copy_bits failed "
+ "with error %d\n", -ret);
+ }
+
+ /* another ether packet sent */
+ ipath_stats.sps_ether_spkts++;
+
+done:
+ /*
+ * we have to flush after trigger word for correctness on
+ * some cpus or WC buffer can be written out of order; needed
+ * even if there was an error
+ */
+ ipath_flush_wc();
+ return ret;
+}
+
+EXPORT_SYMBOL_GPL(ipath_layer_send_skb);
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