b291e9a365
should_yield(). Use this in various places. Encapsulate the common case of check-and-yield into a new function maybe_yield(). Change several checks for a magic number of iterations to use should_yield() instead. MFC after: 1 week
129 lines
4.1 KiB
C
129 lines
4.1 KiB
C
/*-
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* Copyright (c) 2004 Alan L. Cox <alc@cs.rice.edu>
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* Copyright (c) 1982, 1986, 1991, 1993
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* The Regents of the University of California. All rights reserved.
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* (c) UNIX System Laboratories, Inc.
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* All or some portions of this file are derived from material licensed
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* to the University of California by American Telephone and Telegraph
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* Co. or Unix System Laboratories, Inc. and are reproduced herein with
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* the permission of UNIX System Laboratories, Inc.
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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. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its 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 REGENTS 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 REGENTS 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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* @(#)kern_subr.c 8.3 (Berkeley) 1/21/94
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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/lock.h>
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#include <sys/mutex.h>
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#include <sys/proc.h>
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#include <sys/systm.h>
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#include <sys/uio.h>
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#include <sys/sf_buf.h>
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#include <vm/vm.h>
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#include <vm/vm_page.h>
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#include <machine/vmparam.h>
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/*
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* Implement uiomove(9) from physical memory using sf_bufs to
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* avoid the creation and destruction of ephemeral mappings.
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*/
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int
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uiomove_fromphys(vm_page_t ma[], vm_offset_t offset, int n, struct uio *uio)
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{
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struct thread *td = curthread;
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struct iovec *iov;
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void *cp;
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vm_offset_t page_offset;
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size_t cnt;
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int error = 0;
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int save = 0;
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struct sf_buf *sf;
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KASSERT(uio->uio_rw == UIO_READ || uio->uio_rw == UIO_WRITE,
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("uiomove_fromphys: mode"));
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KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
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("uiomove_fromphys proc"));
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save = td->td_pflags & TDP_DEADLKTREAT;
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td->td_pflags |= TDP_DEADLKTREAT;
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while (n > 0 && uio->uio_resid) {
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iov = uio->uio_iov;
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cnt = iov->iov_len;
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if (cnt == 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 (cnt > n)
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cnt = n;
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page_offset = offset & PAGE_MASK;
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cnt = min(cnt, PAGE_SIZE - page_offset);
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sf = sf_buf_alloc(ma[offset >> PAGE_SHIFT], 0);
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cp = (char*)sf_buf_kva(sf) + page_offset;
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switch (uio->uio_segflg) {
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case UIO_USERSPACE:
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maybe_yield();
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if (uio->uio_rw == UIO_READ)
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error = copyout(cp, iov->iov_base, cnt);
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else
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error = copyin(iov->iov_base, cp, cnt);
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if (error) {
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sf_buf_free(sf);
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goto out;
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}
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break;
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case UIO_SYSSPACE:
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if (uio->uio_rw == UIO_READ)
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bcopy(cp, iov->iov_base, cnt);
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else
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bcopy(iov->iov_base, cp, cnt);
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break;
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case UIO_NOCOPY:
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break;
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}
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sf_buf_free(sf);
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iov->iov_base = (char *)iov->iov_base + cnt;
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iov->iov_len -= cnt;
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uio->uio_resid -= cnt;
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uio->uio_offset += cnt;
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offset += cnt;
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n -= cnt;
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}
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out:
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if (save == 0)
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td->td_pflags &= ~TDP_DEADLKTREAT;
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return (error);
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}
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