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c86b6ff551
mutex releases to not require flags for the cases when preemption is not allowed: The purpose of the MTX_NOSWITCH and SWI_NOSWITCH flags is to prevent switching to a higher priority thread on mutex releease and swi schedule, respectively when that switch is not safe. Now that the critical section API maintains a per-thread nesting count, the kernel can easily check whether or not it should switch without relying on flags from the programmer. This fixes a few bugs in that all current callers of swi_sched() used SWI_NOSWITCH, when in fact, only the ones called from fast interrupt handlers and the swi_sched of softclock needed this flag. Note that to ensure that swi_sched()'s in clock and fast interrupt handlers do not switch, these handlers have to be explicitly wrapped in critical_enter/exit pairs. Presently, just wrapping the handlers is sufficient, but in the future with the fully preemptive kernel, the interrupt must be EOI'd before critical_exit() is called. (critical_exit() can switch due to a deferred preemption in a fully preemptive kernel.) I've tested the changes to the interrupt code on i386 and alpha. I have not tested ia64, but the interrupt code is almost identical to the alpha code, so I expect it will work fine. PowerPC and ARM do not yet have interrupt code in the tree so they shouldn't be broken. Sparc64 is broken, but that's been ok'd by jake and tmm who will be fixing the interrupt code for sparc64 shortly. Reviewed by: peter Tested on: i386, alpha
433 lines
9.8 KiB
C
433 lines
9.8 KiB
C
/*
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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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* $FreeBSD$
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/ktr.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/malloc.h>
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#include <sys/resourcevar.h>
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#include <sys/sysctl.h>
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#include <sys/vnode.h>
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#include <vm/vm.h>
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#include <vm/vm_page.h>
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#include <vm/vm_map.h>
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SYSCTL_INT(_kern, KERN_IOV_MAX, iov_max, CTLFLAG_RD, NULL, UIO_MAXIOV,
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"Maximum number of elements in an I/O vector; sysconf(_SC_IOV_MAX)");
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int
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uiomove(cp, n, uio)
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register caddr_t cp;
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register int n;
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register struct uio *uio;
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{
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struct thread *td = curthread;
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register struct iovec *iov;
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u_int cnt;
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int error = 0;
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int save = 0;
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KASSERT(uio->uio_rw == UIO_READ || uio->uio_rw == UIO_WRITE,
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("uiomove: mode"));
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KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
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("uiomove proc"));
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if (td) {
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mtx_lock_spin(&sched_lock);
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save = td->td_flags & TDF_DEADLKTREAT;
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td->td_flags |= TDF_DEADLKTREAT;
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mtx_unlock_spin(&sched_lock);
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}
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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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switch (uio->uio_segflg) {
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case UIO_USERSPACE:
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case UIO_USERISPACE:
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if (ticks - PCPU_GET(switchticks) >= hogticks)
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uio_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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break;
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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((caddr_t)cp, iov->iov_base, cnt);
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else
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bcopy(iov->iov_base, (caddr_t)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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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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cp += cnt;
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n -= cnt;
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}
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if (td != curthread) printf("uiomove: IT CHANGED!");
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td = curthread; /* Might things have changed in copyin/copyout? */
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if (td) {
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mtx_lock_spin(&sched_lock);
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td->td_flags = (td->td_flags & ~TDF_DEADLKTREAT) | save;
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mtx_unlock_spin(&sched_lock);
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}
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return (error);
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}
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int
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uiomoveco(cp, n, uio, obj)
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caddr_t cp;
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int n;
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struct uio *uio;
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struct vm_object *obj;
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{
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struct iovec *iov;
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u_int cnt;
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int error;
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KASSERT(uio->uio_rw == UIO_READ || uio->uio_rw == UIO_WRITE,
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("uiomoveco: mode"));
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KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
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("uiomoveco proc"));
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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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switch (uio->uio_segflg) {
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case UIO_USERSPACE:
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case UIO_USERISPACE:
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if (ticks - PCPU_GET(switchticks) >= hogticks)
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uio_yield();
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if (uio->uio_rw == UIO_READ) {
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#ifdef ENABLE_VFS_IOOPT
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if (vfs_ioopt && ((cnt & PAGE_MASK) == 0) &&
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((((intptr_t) iov->iov_base) & PAGE_MASK) == 0) &&
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((uio->uio_offset & PAGE_MASK) == 0) &&
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((((intptr_t) cp) & PAGE_MASK) == 0)) {
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error = vm_uiomove(&curproc->p_vmspace->vm_map, obj,
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uio->uio_offset, cnt,
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(vm_offset_t) iov->iov_base, NULL);
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} else
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#endif
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{
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error = copyout(cp, iov->iov_base, cnt);
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}
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} else {
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error = copyin(iov->iov_base, cp, cnt);
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}
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if (error)
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return (error);
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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((caddr_t)cp, iov->iov_base, cnt);
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else
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bcopy(iov->iov_base, (caddr_t)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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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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cp += cnt;
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n -= cnt;
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}
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return (0);
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}
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#ifdef ENABLE_VFS_IOOPT
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int
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uioread(n, uio, obj, nread)
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int n;
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struct uio *uio;
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struct vm_object *obj;
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int *nread;
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{
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int npagesmoved;
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struct iovec *iov;
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u_int cnt, tcnt;
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int error;
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*nread = 0;
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if (vfs_ioopt < 2)
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return 0;
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error = 0;
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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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if ((uio->uio_segflg == UIO_USERSPACE) &&
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((((intptr_t) iov->iov_base) & PAGE_MASK) == 0) &&
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((uio->uio_offset & PAGE_MASK) == 0) ) {
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if (cnt < PAGE_SIZE)
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break;
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cnt &= ~PAGE_MASK;
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if (ticks - PCPU_GET(switchticks) >= hogticks)
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uio_yield();
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error = vm_uiomove(&curproc->p_vmspace->vm_map, obj,
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uio->uio_offset, cnt,
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(vm_offset_t) iov->iov_base, &npagesmoved);
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if (npagesmoved == 0)
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break;
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tcnt = npagesmoved * PAGE_SIZE;
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cnt = tcnt;
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if (error)
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break;
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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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*nread += cnt;
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n -= cnt;
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} else {
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break;
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}
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}
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return error;
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}
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#endif
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/*
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* Give next character to user as result of read.
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*/
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int
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ureadc(c, uio)
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register int c;
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register struct uio *uio;
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{
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register struct iovec *iov;
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again:
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if (uio->uio_iovcnt == 0 || uio->uio_resid == 0)
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panic("ureadc");
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iov = uio->uio_iov;
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if (iov->iov_len == 0) {
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uio->uio_iovcnt--;
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uio->uio_iov++;
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goto again;
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}
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switch (uio->uio_segflg) {
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case UIO_USERSPACE:
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if (subyte(iov->iov_base, c) < 0)
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return (EFAULT);
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break;
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case UIO_SYSSPACE:
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*iov->iov_base = c;
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break;
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case UIO_USERISPACE:
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if (suibyte(iov->iov_base, c) < 0)
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return (EFAULT);
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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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iov->iov_base++;
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iov->iov_len--;
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uio->uio_resid--;
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uio->uio_offset++;
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return (0);
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}
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/*
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* General routine to allocate a hash table.
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*/
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void *
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hashinit(elements, type, hashmask)
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int elements;
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struct malloc_type *type;
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u_long *hashmask;
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{
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long hashsize;
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LIST_HEAD(generic, generic) *hashtbl;
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int i;
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if (elements <= 0)
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panic("hashinit: bad elements");
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for (hashsize = 1; hashsize <= elements; hashsize <<= 1)
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continue;
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hashsize >>= 1;
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hashtbl = malloc((u_long)hashsize * sizeof(*hashtbl), type, M_WAITOK);
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for (i = 0; i < hashsize; i++)
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LIST_INIT(&hashtbl[i]);
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*hashmask = hashsize - 1;
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return (hashtbl);
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}
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static int primes[] = { 1, 13, 31, 61, 127, 251, 509, 761, 1021, 1531, 2039,
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2557, 3067, 3583, 4093, 4603, 5119, 5623, 6143, 6653,
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7159, 7673, 8191, 12281, 16381, 24571, 32749 };
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#define NPRIMES (sizeof(primes) / sizeof(primes[0]))
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/*
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* General routine to allocate a prime number sized hash table.
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*/
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void *
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phashinit(elements, type, nentries)
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int elements;
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struct malloc_type *type;
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u_long *nentries;
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{
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long hashsize;
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LIST_HEAD(generic, generic) *hashtbl;
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int i;
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if (elements <= 0)
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panic("phashinit: bad elements");
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for (i = 1, hashsize = primes[1]; hashsize <= elements;) {
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i++;
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if (i == NPRIMES)
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break;
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hashsize = primes[i];
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}
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hashsize = primes[i - 1];
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hashtbl = malloc((u_long)hashsize * sizeof(*hashtbl), type, M_WAITOK);
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for (i = 0; i < hashsize; i++)
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LIST_INIT(&hashtbl[i]);
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*nentries = hashsize;
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return (hashtbl);
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}
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void
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uio_yield()
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{
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struct thread *td;
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td = curthread;
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mtx_lock_spin(&sched_lock);
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DROP_GIANT();
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td->td_ksegrp->kg_pri.pri_level = td->td_ksegrp->kg_pri.pri_user;
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setrunqueue(td);
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td->td_proc->p_stats->p_ru.ru_nivcsw++;
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mi_switch();
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mtx_unlock_spin(&sched_lock);
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PICKUP_GIANT();
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}
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int
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copyinfrom(const void *src, void *dst, size_t len, int seg)
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{
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int error = 0;
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switch (seg) {
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case UIO_USERSPACE:
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error = copyin(src, dst, len);
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break;
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case UIO_SYSSPACE:
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bcopy(src, dst, len);
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break;
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default:
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panic("copyinfrom: bad seg %d\n", seg);
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}
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return (error);
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}
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int
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copyinstrfrom(const void *src, void *dst, size_t len, size_t *copied, int seg)
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{
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int error = 0;
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switch (seg) {
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case UIO_USERSPACE:
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error = copyinstr(src, dst, len, copied);
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break;
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case UIO_SYSSPACE:
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error = copystr(src, dst, len, copied);
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break;
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default:
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panic("copyinstrfrom: bad seg %d\n", seg);
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}
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return (error);
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}
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