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eb5a1e8f38
better semantics if a request to append an address range to an existing list fails. - When cloning an sglist, properly set the length in the new sglist instead of leaving the new list empty. - Properly compute the amount of data added to an sglist via _sglist_append_buf(). This allows sglist_consume_uio() to properly update uio_resid. - When a request to append an address range to a scatter/gather list fails, restore the sglist to the state it had at the start of the function call instead of resetting it to an empty list. Requested by: np (3) Approved by: re (kib)
715 lines
17 KiB
C
715 lines
17 KiB
C
/*-
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* Copyright (c) 2008 Yahoo!, Inc.
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* All rights reserved.
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* Written by: John Baldwin <jhb@FreeBSD.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the author nor the names of any co-contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/kernel.h>
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#include <sys/malloc.h>
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#include <sys/mbuf.h>
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#include <sys/proc.h>
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#include <sys/sglist.h>
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#include <sys/uio.h>
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#include <vm/vm.h>
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#include <vm/pmap.h>
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#include <vm/vm_map.h>
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#include <sys/ktr.h>
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static MALLOC_DEFINE(M_SGLIST, "sglist", "scatter/gather lists");
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/*
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* Convenience macros to save the state of an sglist so it can be restored
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* if an append attempt fails. Since sglist's only grow we only need to
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* save the current count of segments and the length of the ending segment.
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* Earlier segments will not be changed by an append, and the only change
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* that can occur to the ending segment is that it can be extended.
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*/
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struct sgsave {
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u_short sg_nseg;
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size_t ss_len;
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};
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#define SGLIST_SAVE(sg, sgsave) do { \
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(sgsave).sg_nseg = (sg)->sg_nseg; \
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if ((sgsave).sg_nseg > 0) \
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(sgsave).ss_len = (sg)->sg_segs[(sgsave).sg_nseg - 1].ss_len; \
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else \
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(sgsave).ss_len = 0; \
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} while (0)
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#define SGLIST_RESTORE(sg, sgsave) do { \
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(sg)->sg_nseg = (sgsave).sg_nseg; \
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if ((sgsave).sg_nseg > 0) \
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(sg)->sg_segs[(sgsave).sg_nseg - 1].ss_len = (sgsave).ss_len; \
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} while (0)
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/*
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* Append a single (paddr, len) to a sglist. sg is the list and ss is
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* the current segment in the list. If we run out of segments then
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* EFBIG will be returned.
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*/
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static __inline int
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_sglist_append_range(struct sglist *sg, struct sglist_seg **ssp,
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vm_paddr_t paddr, size_t len)
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{
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struct sglist_seg *ss;
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ss = *ssp;
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if (ss->ss_paddr + ss->ss_len == paddr)
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ss->ss_len += len;
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else {
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if (sg->sg_nseg == sg->sg_maxseg)
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return (EFBIG);
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ss++;
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ss->ss_paddr = paddr;
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ss->ss_len = len;
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sg->sg_nseg++;
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*ssp = ss;
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}
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return (0);
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}
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/*
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* Worker routine to append a virtual address range (either kernel or
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* user) to a scatter/gather list.
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*/
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static __inline int
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_sglist_append_buf(struct sglist *sg, void *buf, size_t len, pmap_t pmap,
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size_t *donep)
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{
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struct sglist_seg *ss;
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vm_offset_t vaddr, offset;
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vm_paddr_t paddr;
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size_t seglen;
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int error;
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if (donep)
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*donep = 0;
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if (len == 0)
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return (0);
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/* Do the first page. It may have an offset. */
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vaddr = (vm_offset_t)buf;
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offset = vaddr & PAGE_MASK;
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if (pmap != NULL)
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paddr = pmap_extract(pmap, vaddr);
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else
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paddr = pmap_kextract(vaddr);
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seglen = MIN(len, PAGE_SIZE - offset);
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if (sg->sg_nseg == 0) {
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ss = sg->sg_segs;
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ss->ss_paddr = paddr;
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ss->ss_len = seglen;
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sg->sg_nseg = 1;
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} else {
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ss = &sg->sg_segs[sg->sg_nseg - 1];
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error = _sglist_append_range(sg, &ss, paddr, seglen);
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if (error)
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return (error);
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}
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vaddr += seglen;
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len -= seglen;
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if (donep)
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*donep += seglen;
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while (len > 0) {
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seglen = MIN(len, PAGE_SIZE);
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if (pmap != NULL)
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paddr = pmap_extract(pmap, vaddr);
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else
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paddr = pmap_kextract(vaddr);
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error = _sglist_append_range(sg, &ss, paddr, seglen);
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if (error)
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return (error);
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vaddr += seglen;
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len -= seglen;
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if (donep)
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*donep += seglen;
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}
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return (0);
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}
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/*
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* Determine the number of scatter/gather list elements needed to
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* describe a kernel virtual address range.
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*/
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int
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sglist_count(void *buf, size_t len)
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{
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vm_offset_t vaddr, vendaddr;
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vm_paddr_t lastaddr, paddr;
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int nsegs;
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if (len == 0)
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return (0);
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vaddr = trunc_page((vm_offset_t)buf);
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vendaddr = (vm_offset_t)buf + len;
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nsegs = 1;
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lastaddr = pmap_kextract(vaddr);
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vaddr += PAGE_SIZE;
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while (vaddr < vendaddr) {
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paddr = pmap_kextract(vaddr);
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if (lastaddr + PAGE_SIZE != paddr)
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nsegs++;
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lastaddr = paddr;
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vaddr += PAGE_SIZE;
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}
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return (nsegs);
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}
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/*
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* Allocate a scatter/gather list along with 'nsegs' segments. The
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* 'mflags' parameters are the same as passed to malloc(9). The caller
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* should use sglist_free() to free this list.
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*/
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struct sglist *
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sglist_alloc(int nsegs, int mflags)
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{
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struct sglist *sg;
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sg = malloc(sizeof(struct sglist) + nsegs * sizeof(struct sglist_seg),
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M_SGLIST, mflags);
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if (sg == NULL)
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return (NULL);
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sglist_init(sg, nsegs, (struct sglist_seg *)(sg + 1));
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return (sg);
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}
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/*
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* Free a scatter/gather list allocated via sglist_allc().
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*/
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void
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sglist_free(struct sglist *sg)
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{
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if (refcount_release(&sg->sg_refs))
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free(sg, M_SGLIST);
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}
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/*
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* Append the segments to describe a single kernel virtual address
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* range to a scatter/gather list. If there are insufficient
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* segments, then this fails with EFBIG.
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*/
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int
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sglist_append(struct sglist *sg, void *buf, size_t len)
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{
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struct sgsave save;
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int error;
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if (sg->sg_maxseg == 0)
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return (EINVAL);
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SGLIST_SAVE(sg, save);
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error = _sglist_append_buf(sg, buf, len, NULL, NULL);
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if (error)
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SGLIST_RESTORE(sg, save);
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return (error);
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}
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/*
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* Append a single physical address range to a scatter/gather list.
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* If there are insufficient segments, then this fails with EFBIG.
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*/
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int
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sglist_append_phys(struct sglist *sg, vm_paddr_t paddr, size_t len)
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{
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struct sglist_seg *ss;
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struct sgsave save;
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int error;
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if (sg->sg_maxseg == 0)
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return (EINVAL);
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if (len == 0)
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return (0);
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if (sg->sg_nseg == 0) {
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sg->sg_segs[0].ss_paddr = paddr;
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sg->sg_segs[0].ss_len = len;
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sg->sg_nseg = 1;
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return (0);
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}
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ss = &sg->sg_segs[sg->sg_nseg - 1];
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SGLIST_SAVE(sg, save);
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error = _sglist_append_range(sg, &ss, paddr, len);
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if (error)
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SGLIST_RESTORE(sg, save);
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return (error);
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}
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/*
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* Append the segments that describe a single mbuf chain to a
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* scatter/gather list. If there are insufficient segments, then this
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* fails with EFBIG.
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*/
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int
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sglist_append_mbuf(struct sglist *sg, struct mbuf *m0)
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{
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struct sgsave save;
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struct mbuf *m;
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int error;
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if (sg->sg_maxseg == 0)
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return (EINVAL);
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error = 0;
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SGLIST_SAVE(sg, save);
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for (m = m0; m != NULL; m = m->m_next) {
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if (m->m_len > 0) {
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error = sglist_append(sg, m->m_data, m->m_len);
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if (error) {
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SGLIST_RESTORE(sg, save);
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return (error);
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}
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}
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}
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return (0);
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}
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/*
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* Append the segments that describe a single user address range to a
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* scatter/gather list. If there are insufficient segments, then this
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* fails with EFBIG.
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*/
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int
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sglist_append_user(struct sglist *sg, void *buf, size_t len, struct thread *td)
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{
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struct sgsave save;
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int error;
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if (sg->sg_maxseg == 0)
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return (EINVAL);
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SGLIST_SAVE(sg, save);
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error = _sglist_append_buf(sg, buf, len,
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vmspace_pmap(td->td_proc->p_vmspace), NULL);
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if (error)
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SGLIST_RESTORE(sg, save);
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return (error);
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}
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/*
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* Append the segments that describe a single uio to a scatter/gather
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* list. If there are insufficient segments, then this fails with
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* EFBIG.
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*/
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int
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sglist_append_uio(struct sglist *sg, struct uio *uio)
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{
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struct iovec *iov;
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struct sgsave save;
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size_t resid, minlen;
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pmap_t pmap;
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int error, i;
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if (sg->sg_maxseg == 0)
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return (EINVAL);
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resid = uio->uio_resid;
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iov = uio->uio_iov;
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if (uio->uio_segflg == UIO_USERSPACE) {
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KASSERT(uio->uio_td != NULL,
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("sglist_append_uio: USERSPACE but no thread"));
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pmap = vmspace_pmap(uio->uio_td->td_proc->p_vmspace);
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} else
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pmap = NULL;
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error = 0;
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SGLIST_SAVE(sg, save);
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for (i = 0; i < uio->uio_iovcnt && resid != 0; i++) {
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/*
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* Now at the first iovec to load. Load each iovec
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* until we have exhausted the residual count.
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*/
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minlen = MIN(resid, iov[i].iov_len);
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if (minlen > 0) {
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error = _sglist_append_buf(sg, iov[i].iov_base, minlen,
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pmap, NULL);
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if (error) {
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SGLIST_RESTORE(sg, save);
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return (error);
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}
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resid -= minlen;
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}
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}
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return (0);
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}
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/*
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* Append the segments that describe at most 'resid' bytes from a
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* single uio to a scatter/gather list. If there are insufficient
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* segments, then only the amount that fits is appended.
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*/
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int
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sglist_consume_uio(struct sglist *sg, struct uio *uio, size_t resid)
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{
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struct iovec *iov;
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size_t done;
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pmap_t pmap;
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int error, len;
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if (sg->sg_maxseg == 0)
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return (EINVAL);
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if (uio->uio_segflg == UIO_USERSPACE) {
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KASSERT(uio->uio_td != NULL,
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("sglist_consume_uio: USERSPACE but no thread"));
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pmap = vmspace_pmap(uio->uio_td->td_proc->p_vmspace);
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} else
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pmap = NULL;
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error = 0;
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while (resid > 0 && uio->uio_resid) {
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iov = uio->uio_iov;
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len = iov->iov_len;
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if (len == 0) {
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uio->uio_iov++;
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uio->uio_iovcnt--;
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continue;
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}
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if (len > resid)
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len = resid;
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/*
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* Try to append this iovec. If we run out of room,
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* then break out of the loop.
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*/
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error = _sglist_append_buf(sg, iov->iov_base, len, pmap, &done);
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iov->iov_base = (char *)iov->iov_base + done;
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iov->iov_len -= done;
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uio->uio_resid -= done;
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uio->uio_offset += done;
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resid -= done;
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if (error)
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break;
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}
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return (0);
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}
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/*
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* Allocate and populate a scatter/gather list to describe a single
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* kernel virtual address range.
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*/
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struct sglist *
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sglist_build(void *buf, size_t len, int mflags)
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{
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struct sglist *sg;
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int nsegs;
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if (len == 0)
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return (NULL);
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nsegs = sglist_count(buf, len);
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sg = sglist_alloc(nsegs, mflags);
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if (sg == NULL)
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return (NULL);
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if (sglist_append(sg, buf, len) != 0) {
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sglist_free(sg);
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return (NULL);
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}
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return (sg);
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}
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/*
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* Clone a new copy of a scatter/gather list.
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*/
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struct sglist *
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sglist_clone(struct sglist *sg, int mflags)
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{
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struct sglist *new;
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if (sg == NULL)
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return (NULL);
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new = sglist_alloc(sg->sg_maxseg, mflags);
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if (new == NULL)
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return (NULL);
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new->sg_nseg = sg->sg_nseg;
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bcopy(sg->sg_segs, new->sg_segs, sizeof(struct sglist_seg) *
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sg->sg_nseg);
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return (new);
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}
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/*
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* Calculate the total length of the segments described in a
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* scatter/gather list.
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*/
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size_t
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sglist_length(struct sglist *sg)
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{
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size_t space;
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int i;
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space = 0;
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for (i = 0; i < sg->sg_nseg; i++)
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space += sg->sg_segs[i].ss_len;
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return (space);
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}
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/*
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* Split a scatter/gather list into two lists. The scatter/gather
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* entries for the first 'length' bytes of the 'original' list are
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* stored in the '*head' list and are removed from 'original'.
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*
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* If '*head' is NULL, then a new list will be allocated using
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* 'mflags'. If M_NOWAIT is specified and the allocation fails,
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* ENOMEM will be returned.
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*
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* If '*head' is not NULL, it should point to an empty sglist. If it
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* does not have enough room for the remaining space, then EFBIG will
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* be returned. If '*head' is not empty, then EINVAL will be
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* returned.
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*
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* If 'original' is shared (refcount > 1), then EDOOFUS will be
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* returned.
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*/
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int
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sglist_split(struct sglist *original, struct sglist **head, size_t length,
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int mflags)
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{
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struct sglist *sg;
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size_t space, split;
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int count, i;
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if (original->sg_refs > 1)
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return (EDOOFUS);
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/* Figure out how big of a sglist '*head' has to hold. */
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count = 0;
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space = 0;
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split = 0;
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for (i = 0; i < original->sg_nseg; i++) {
|
|
space += original->sg_segs[i].ss_len;
|
|
count++;
|
|
if (space >= length) {
|
|
/*
|
|
* If 'length' falls in the middle of a
|
|
* scatter/gather list entry, then 'split'
|
|
* holds how much of that entry will remain in
|
|
* 'original'.
|
|
*/
|
|
split = space - length;
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* Nothing to do, so leave head empty. */
|
|
if (count == 0)
|
|
return (0);
|
|
|
|
if (*head == NULL) {
|
|
sg = sglist_alloc(count, mflags);
|
|
if (sg == NULL)
|
|
return (ENOMEM);
|
|
*head = sg;
|
|
} else {
|
|
sg = *head;
|
|
if (sg->sg_maxseg < count)
|
|
return (EFBIG);
|
|
if (sg->sg_nseg != 0)
|
|
return (EINVAL);
|
|
}
|
|
|
|
/* Copy 'count' entries to 'sg' from 'original'. */
|
|
bcopy(original->sg_segs, sg->sg_segs, count *
|
|
sizeof(struct sglist_seg));
|
|
sg->sg_nseg = count;
|
|
|
|
/*
|
|
* If we had to split a list entry, fixup the last entry in
|
|
* 'sg' and the new first entry in 'original'. We also
|
|
* decrement 'count' by 1 since we will only be removing
|
|
* 'count - 1' segments from 'original' now.
|
|
*/
|
|
if (split != 0) {
|
|
count--;
|
|
sg->sg_segs[count].ss_len -= split;
|
|
original->sg_segs[count].ss_paddr =
|
|
sg->sg_segs[count].ss_paddr + split;
|
|
original->sg_segs[count].ss_len = split;
|
|
}
|
|
|
|
/* Trim 'count' entries from the front of 'original'. */
|
|
original->sg_nseg -= count;
|
|
bcopy(original->sg_segs + count, original->sg_segs, count *
|
|
sizeof(struct sglist_seg));
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* Append the scatter/gather list elements in 'second' to the
|
|
* scatter/gather list 'first'. If there is not enough space in
|
|
* 'first', EFBIG is returned.
|
|
*/
|
|
int
|
|
sglist_join(struct sglist *first, struct sglist *second)
|
|
{
|
|
struct sglist_seg *flast, *sfirst;
|
|
int append;
|
|
|
|
/* If 'second' is empty, there is nothing to do. */
|
|
if (second->sg_nseg == 0)
|
|
return (0);
|
|
|
|
/*
|
|
* If the first entry in 'second' can be appended to the last entry
|
|
* in 'first' then set append to '1'.
|
|
*/
|
|
append = 0;
|
|
flast = &first->sg_segs[first->sg_nseg - 1];
|
|
sfirst = &second->sg_segs[0];
|
|
if (first->sg_nseg != 0 &&
|
|
flast->ss_paddr + flast->ss_len == sfirst->ss_paddr)
|
|
append = 1;
|
|
|
|
/* Make sure 'first' has enough room. */
|
|
if (first->sg_nseg + second->sg_nseg - append > first->sg_maxseg)
|
|
return (EFBIG);
|
|
|
|
/* Merge last in 'first' and first in 'second' if needed. */
|
|
if (append)
|
|
flast->ss_len += sfirst->ss_len;
|
|
|
|
/* Append new segments from 'second' to 'first'. */
|
|
bcopy(first->sg_segs + first->sg_nseg, second->sg_segs + append,
|
|
(second->sg_nseg - append) * sizeof(struct sglist_seg));
|
|
first->sg_nseg += second->sg_nseg - append;
|
|
sglist_reset(second);
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* Generate a new scatter/gather list from a range of an existing
|
|
* scatter/gather list. The 'offset' and 'length' parameters specify
|
|
* the logical range of the 'original' list to extract. If that range
|
|
* is not a subset of the length of 'original', then EINVAL is
|
|
* returned. The new scatter/gather list is stored in '*slice'.
|
|
*
|
|
* If '*slice' is NULL, then a new list will be allocated using
|
|
* 'mflags'. If M_NOWAIT is specified and the allocation fails,
|
|
* ENOMEM will be returned.
|
|
*
|
|
* If '*slice' is not NULL, it should point to an empty sglist. If it
|
|
* does not have enough room for the remaining space, then EFBIG will
|
|
* be returned. If '*slice' is not empty, then EINVAL will be
|
|
* returned.
|
|
*/
|
|
int
|
|
sglist_slice(struct sglist *original, struct sglist **slice, size_t offset,
|
|
size_t length, int mflags)
|
|
{
|
|
struct sglist *sg;
|
|
size_t space, end, foffs, loffs;
|
|
int count, i, fseg;
|
|
|
|
/* Nothing to do. */
|
|
if (length == 0)
|
|
return (0);
|
|
|
|
/* Figure out how many segments '*slice' needs to have. */
|
|
end = offset + length;
|
|
space = 0;
|
|
count = 0;
|
|
fseg = 0;
|
|
foffs = loffs = 0;
|
|
for (i = 0; i < original->sg_nseg; i++) {
|
|
space += original->sg_segs[i].ss_len;
|
|
if (space > offset) {
|
|
/*
|
|
* When we hit the first segment, store its index
|
|
* in 'fseg' and the offset into the first segment
|
|
* of 'offset' in 'foffs'.
|
|
*/
|
|
if (count == 0) {
|
|
fseg = i;
|
|
foffs = offset - (space -
|
|
original->sg_segs[i].ss_len);
|
|
CTR1(KTR_DEV, "sglist_slice: foffs = %08lx",
|
|
foffs);
|
|
}
|
|
count++;
|
|
|
|
/*
|
|
* When we hit the last segment, break out of
|
|
* the loop. Store the amount of extra space
|
|
* at the end of this segment in 'loffs'.
|
|
*/
|
|
if (space >= end) {
|
|
loffs = space - end;
|
|
CTR1(KTR_DEV, "sglist_slice: loffs = %08lx",
|
|
loffs);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
/* If we never hit 'end', then 'length' ran off the end, so fail. */
|
|
if (space < end)
|
|
return (EINVAL);
|
|
|
|
if (*slice == NULL) {
|
|
sg = sglist_alloc(count, mflags);
|
|
if (sg == NULL)
|
|
return (ENOMEM);
|
|
*slice = sg;
|
|
} else {
|
|
sg = *slice;
|
|
if (sg->sg_maxseg < count)
|
|
return (EFBIG);
|
|
if (sg->sg_nseg != 0)
|
|
return (EINVAL);
|
|
}
|
|
|
|
/*
|
|
* Copy over 'count' segments from 'original' starting at
|
|
* 'fseg' to 'sg'.
|
|
*/
|
|
bcopy(original->sg_segs + fseg, sg->sg_segs,
|
|
count * sizeof(struct sglist_seg));
|
|
sg->sg_nseg = count;
|
|
|
|
/* Fixup first and last segments if needed. */
|
|
if (foffs != 0) {
|
|
sg->sg_segs[0].ss_paddr += foffs;
|
|
sg->sg_segs[0].ss_len -= foffs;
|
|
CTR2(KTR_DEV, "sglist_slice seg[0]: %08lx:%08lx",
|
|
(long)sg->sg_segs[0].ss_paddr, sg->sg_segs[0].ss_len);
|
|
}
|
|
if (loffs != 0) {
|
|
sg->sg_segs[count - 1].ss_len -= loffs;
|
|
CTR2(KTR_DEV, "sglist_slice seg[%d]: len %08x", count - 1,
|
|
sg->sg_segs[count - 1].ss_len);
|
|
}
|
|
return (0);
|
|
}
|