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![Dan Williams](/assets/img/avatar_default.png)
Handle descriptor allocation failures by polling for a descriptor. The driver will force forward progress when polled. In the best case this polling interval will be the time it takes for one dma memcpy transaction to complete. In the worst case, channel hang, we will need to wait 100ms for the cleanup watchdog to fire (ioatdma driver). Signed-off-by: Maciej Sosnowski <maciej.sosnowski@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
279 lines
7.3 KiB
C
279 lines
7.3 KiB
C
/*
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* Copyright(c) 2004 - 2006 Intel Corporation. All rights reserved.
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* Portions based on net/core/datagram.c and copyrighted by their authors.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program; if not, write to the Free Software Foundation, Inc., 59
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* Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*
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* The full GNU General Public License is included in this distribution in the
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* file called COPYING.
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*/
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/*
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* This code allows the net stack to make use of a DMA engine for
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* skb to iovec copies.
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*/
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#include <linux/dmaengine.h>
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#include <linux/pagemap.h>
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#include <net/tcp.h> /* for memcpy_toiovec */
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#include <asm/io.h>
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#include <asm/uaccess.h>
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static int num_pages_spanned(struct iovec *iov)
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{
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return
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((PAGE_ALIGN((unsigned long)iov->iov_base + iov->iov_len) -
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((unsigned long)iov->iov_base & PAGE_MASK)) >> PAGE_SHIFT);
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}
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/*
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* Pin down all the iovec pages needed for len bytes.
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* Return a struct dma_pinned_list to keep track of pages pinned down.
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*
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* We are allocating a single chunk of memory, and then carving it up into
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* 3 sections, the latter 2 whose size depends on the number of iovecs and the
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* total number of pages, respectively.
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*/
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struct dma_pinned_list *dma_pin_iovec_pages(struct iovec *iov, size_t len)
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{
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struct dma_pinned_list *local_list;
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struct page **pages;
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int i;
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int ret;
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int nr_iovecs = 0;
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int iovec_len_used = 0;
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int iovec_pages_used = 0;
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/* don't pin down non-user-based iovecs */
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if (segment_eq(get_fs(), KERNEL_DS))
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return NULL;
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/* determine how many iovecs/pages there are, up front */
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do {
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iovec_len_used += iov[nr_iovecs].iov_len;
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iovec_pages_used += num_pages_spanned(&iov[nr_iovecs]);
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nr_iovecs++;
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} while (iovec_len_used < len);
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/* single kmalloc for pinned list, page_list[], and the page arrays */
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local_list = kmalloc(sizeof(*local_list)
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+ (nr_iovecs * sizeof (struct dma_page_list))
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+ (iovec_pages_used * sizeof (struct page*)), GFP_KERNEL);
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if (!local_list)
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goto out;
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/* list of pages starts right after the page list array */
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pages = (struct page **) &local_list->page_list[nr_iovecs];
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local_list->nr_iovecs = 0;
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for (i = 0; i < nr_iovecs; i++) {
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struct dma_page_list *page_list = &local_list->page_list[i];
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len -= iov[i].iov_len;
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if (!access_ok(VERIFY_WRITE, iov[i].iov_base, iov[i].iov_len))
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goto unpin;
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page_list->nr_pages = num_pages_spanned(&iov[i]);
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page_list->base_address = iov[i].iov_base;
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page_list->pages = pages;
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pages += page_list->nr_pages;
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/* pin pages down */
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down_read(¤t->mm->mmap_sem);
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ret = get_user_pages(
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current,
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current->mm,
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(unsigned long) iov[i].iov_base,
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page_list->nr_pages,
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1, /* write */
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0, /* force */
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page_list->pages,
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NULL);
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up_read(¤t->mm->mmap_sem);
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if (ret != page_list->nr_pages)
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goto unpin;
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local_list->nr_iovecs = i + 1;
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}
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return local_list;
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unpin:
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dma_unpin_iovec_pages(local_list);
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out:
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return NULL;
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}
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void dma_unpin_iovec_pages(struct dma_pinned_list *pinned_list)
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{
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int i, j;
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if (!pinned_list)
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return;
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for (i = 0; i < pinned_list->nr_iovecs; i++) {
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struct dma_page_list *page_list = &pinned_list->page_list[i];
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for (j = 0; j < page_list->nr_pages; j++) {
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set_page_dirty_lock(page_list->pages[j]);
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page_cache_release(page_list->pages[j]);
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}
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}
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kfree(pinned_list);
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}
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/*
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* We have already pinned down the pages we will be using in the iovecs.
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* Each entry in iov array has corresponding entry in pinned_list->page_list.
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* Using array indexing to keep iov[] and page_list[] in sync.
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* Initial elements in iov array's iov->iov_len will be 0 if already copied into
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* by another call.
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* iov array length remaining guaranteed to be bigger than len.
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*/
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dma_cookie_t dma_memcpy_to_iovec(struct dma_chan *chan, struct iovec *iov,
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struct dma_pinned_list *pinned_list, unsigned char *kdata, size_t len)
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{
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int iov_byte_offset;
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int copy;
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dma_cookie_t dma_cookie = 0;
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int iovec_idx;
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int page_idx;
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if (!chan)
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return memcpy_toiovec(iov, kdata, len);
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iovec_idx = 0;
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while (iovec_idx < pinned_list->nr_iovecs) {
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struct dma_page_list *page_list;
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/* skip already used-up iovecs */
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while (!iov[iovec_idx].iov_len)
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iovec_idx++;
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page_list = &pinned_list->page_list[iovec_idx];
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iov_byte_offset = ((unsigned long)iov[iovec_idx].iov_base & ~PAGE_MASK);
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page_idx = (((unsigned long)iov[iovec_idx].iov_base & PAGE_MASK)
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- ((unsigned long)page_list->base_address & PAGE_MASK)) >> PAGE_SHIFT;
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/* break up copies to not cross page boundary */
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while (iov[iovec_idx].iov_len) {
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copy = min_t(int, PAGE_SIZE - iov_byte_offset, len);
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copy = min_t(int, copy, iov[iovec_idx].iov_len);
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dma_cookie = dma_async_memcpy_buf_to_pg(chan,
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page_list->pages[page_idx],
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iov_byte_offset,
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kdata,
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copy);
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/* poll for a descriptor slot */
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if (unlikely(dma_cookie < 0)) {
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dma_async_issue_pending(chan);
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continue;
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}
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len -= copy;
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iov[iovec_idx].iov_len -= copy;
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iov[iovec_idx].iov_base += copy;
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if (!len)
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return dma_cookie;
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kdata += copy;
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iov_byte_offset = 0;
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page_idx++;
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}
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iovec_idx++;
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}
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/* really bad if we ever run out of iovecs */
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BUG();
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return -EFAULT;
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}
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dma_cookie_t dma_memcpy_pg_to_iovec(struct dma_chan *chan, struct iovec *iov,
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struct dma_pinned_list *pinned_list, struct page *page,
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unsigned int offset, size_t len)
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{
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int iov_byte_offset;
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int copy;
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dma_cookie_t dma_cookie = 0;
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int iovec_idx;
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int page_idx;
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int err;
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/* this needs as-yet-unimplemented buf-to-buff, so punt. */
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/* TODO: use dma for this */
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if (!chan || !pinned_list) {
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u8 *vaddr = kmap(page);
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err = memcpy_toiovec(iov, vaddr + offset, len);
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kunmap(page);
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return err;
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}
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iovec_idx = 0;
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while (iovec_idx < pinned_list->nr_iovecs) {
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struct dma_page_list *page_list;
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/* skip already used-up iovecs */
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while (!iov[iovec_idx].iov_len)
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iovec_idx++;
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page_list = &pinned_list->page_list[iovec_idx];
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iov_byte_offset = ((unsigned long)iov[iovec_idx].iov_base & ~PAGE_MASK);
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page_idx = (((unsigned long)iov[iovec_idx].iov_base & PAGE_MASK)
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- ((unsigned long)page_list->base_address & PAGE_MASK)) >> PAGE_SHIFT;
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/* break up copies to not cross page boundary */
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while (iov[iovec_idx].iov_len) {
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copy = min_t(int, PAGE_SIZE - iov_byte_offset, len);
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copy = min_t(int, copy, iov[iovec_idx].iov_len);
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dma_cookie = dma_async_memcpy_pg_to_pg(chan,
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page_list->pages[page_idx],
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iov_byte_offset,
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page,
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offset,
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copy);
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/* poll for a descriptor slot */
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if (unlikely(dma_cookie < 0)) {
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dma_async_issue_pending(chan);
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continue;
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}
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len -= copy;
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iov[iovec_idx].iov_len -= copy;
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iov[iovec_idx].iov_base += copy;
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if (!len)
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return dma_cookie;
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offset += copy;
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iov_byte_offset = 0;
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page_idx++;
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}
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iovec_idx++;
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}
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/* really bad if we ever run out of iovecs */
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BUG();
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return -EFAULT;
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}
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