14ae95f735
they aren't in the usual path of execution for syscalls and traps. The main complication for this is that we have to set flags to control ast() everywhere that changes the signal mask. Avoid locking in userret() in most of the remaining cases. Submitted by: luoqi (first part only, long ago, reorganized by me) Reminded by: dillon
215 lines
6.3 KiB
C
215 lines
6.3 KiB
C
/*-
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* Copyright (C) 1994, David Greenman
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* Copyright (c) 1990, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* the University of Utah, and William Jolitz.
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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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* from: @(#)trap.c 7.4 (Berkeley) 5/13/91
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* $FreeBSD$
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*/
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#ifdef __i386__
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#include "opt_npx.h"
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#endif
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#include <sys/param.h>
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#include <sys/bus.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/resourcevar.h>
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#include <sys/signalvar.h>
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#include <sys/systm.h>
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#include <sys/vmmeter.h>
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#include <machine/cpu.h>
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#include <machine/pcb.h>
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/*
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* Define the code needed before returning to user mode, for
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* trap and syscall.
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*
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* MPSAFE
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*/
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void
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userret(td, frame, oticks)
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struct thread *td;
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struct trapframe *frame;
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u_int oticks;
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{
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struct proc *p = td->td_proc;
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struct kse *ke = td->td_kse;
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struct ksegrp *kg = td->td_ksegrp;
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#ifdef INVARIANTS
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/* Check that we called signotify() enough. */
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mtx_lock(&Giant);
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PROC_LOCK(p);
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mtx_lock_spin(&sched_lock);
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if (SIGPENDING(p) && ((p->p_sflag & PS_NEEDSIGCHK) == 0 ||
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(p->p_kse.ke_flags & KEF_ASTPENDING) == 0))
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printf("failed to set signal flags proprly for ast()\n");
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mtx_unlock_spin(&sched_lock);
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PROC_UNLOCK(p);
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mtx_unlock(&Giant);
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#endif
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/*
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* XXX we cheat slightly on the locking here to avoid locking in
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* the usual case. Setting td_priority here is essentially an
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* incomplete workaround for not setting it properly elsewhere.
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* Now that some interrupt handlers are threads, not setting it
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* properly elsewhere can clobber it in the window between setting
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* it here and returning to user mode, so don't waste time setting
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* it perfectly here.
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*/
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if (td->td_priority != kg->kg_user_pri) {
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mtx_lock_spin(&sched_lock);
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td->td_priority = kg->kg_user_pri;
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mtx_unlock_spin(&sched_lock);
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}
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/*
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* Charge system time if profiling.
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*
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* XXX should move PS_PROFIL to a place that can obviously be
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* accessed safely without sched_lock.
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*/
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if (p->p_sflag & PS_PROFIL) {
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quad_t ticks;
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mtx_lock_spin(&sched_lock);
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ticks = ke->ke_sticks - oticks;
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mtx_unlock_spin(&sched_lock);
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addupc_task(ke, TRAPF_PC(frame), (u_int)ticks * psratio);
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}
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}
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/*
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* Process an asynchronous software trap.
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* This is relatively easy.
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* This function will return with preemption disabled.
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*/
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void
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ast(framep)
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struct trapframe *framep;
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{
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struct thread *td = curthread;
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struct proc *p = td->td_proc;
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struct kse *ke = td->td_kse;
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struct ksegrp *kg = td->td_ksegrp;
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u_int prticks, sticks;
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int sflag;
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int flags;
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int sig;
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#if defined(DEV_NPX) && !defined(SMP)
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int ucode;
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#endif
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KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode"));
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#ifdef WITNESS
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if (witness_list(td))
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panic("Returning to user mode with mutex(s) held");
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#endif
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mtx_assert(&Giant, MA_NOTOWNED);
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mtx_assert(&sched_lock, MA_NOTOWNED);
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prticks = 0; /* XXX: Quiet warning. */
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td->td_frame = framep;
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/*
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* This updates the p_sflag's for the checks below in one
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* "atomic" operation with turning off the astpending flag.
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* If another AST is triggered while we are handling the
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* AST's saved in sflag, the astpending flag will be set and
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* ast() will be called again.
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*/
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mtx_lock_spin(&sched_lock);
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sticks = ke->ke_sticks;
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sflag = p->p_sflag;
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flags = ke->ke_flags;
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p->p_sflag &= ~(PS_ALRMPEND | PS_NEEDSIGCHK | PS_PROFPEND);
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ke->ke_flags &= ~(KEF_ASTPENDING | KEF_NEEDRESCHED | KEF_OWEUPC);
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cnt.v_soft++;
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if (flags & KEF_OWEUPC && sflag & PS_PROFIL) {
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prticks = p->p_stats->p_prof.pr_ticks;
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p->p_stats->p_prof.pr_ticks = 0;
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}
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mtx_unlock_spin(&sched_lock);
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if (td->td_ucred != p->p_ucred)
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cred_update_thread(td);
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if (flags & KEF_OWEUPC && sflag & PS_PROFIL)
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addupc_task(ke, p->p_stats->p_prof.pr_addr, prticks);
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if (sflag & PS_ALRMPEND) {
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PROC_LOCK(p);
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psignal(p, SIGVTALRM);
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PROC_UNLOCK(p);
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}
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#if defined(DEV_NPX) && !defined(SMP)
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if (PCPU_GET(curpcb)->pcb_flags & PCB_NPXTRAP) {
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atomic_clear_int(&PCPU_GET(curpcb)->pcb_flags,
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PCB_NPXTRAP);
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ucode = npxtrap();
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if (ucode != -1) {
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trapsignal(p, SIGFPE, ucode);
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}
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}
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#endif
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if (sflag & PS_PROFPEND) {
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PROC_LOCK(p);
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psignal(p, SIGPROF);
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PROC_UNLOCK(p);
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}
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if (flags & KEF_NEEDRESCHED) {
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mtx_lock_spin(&sched_lock);
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td->td_priority = kg->kg_user_pri;
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setrunqueue(td);
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p->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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}
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if (sflag & PS_NEEDSIGCHK) {
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mtx_lock(&Giant);
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PROC_LOCK(p);
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while ((sig = CURSIG(p)) != 0)
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postsig(sig);
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PROC_UNLOCK(p);
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mtx_unlock(&Giant);
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}
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userret(td, framep, sticks);
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#ifdef DIAGNOSTIC
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cred_free_thread(td);
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#endif
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mtx_assert(&Giant, MA_NOTOWNED);
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}
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