0dbb100b9b
data structure called kse_upcall to manage UPCALL. All KSE binding and loaning code are gone. A thread owns an upcall can collect all completed syscall contexts in its ksegrp, turn itself into UPCALL mode, and takes those contexts back to userland. Any thread without upcall structure has to export their contexts and exit at user boundary. Any thread running in user mode owns an upcall structure, when it enters kernel, if the kse mailbox's current thread pointer is not NULL, then when the thread is blocked in kernel, a new UPCALL thread is created and the upcall structure is transfered to the new UPCALL thread. if the kse mailbox's current thread pointer is NULL, then when a thread is blocked in kernel, no UPCALL thread will be created. Each upcall always has an owner thread. Userland can remove an upcall by calling kse_exit, when all upcalls in ksegrp are removed, the group is atomatically shutdown. An upcall owner thread also exits when process is in exiting state. when an owner thread exits, the upcall it owns is also removed. KSE is a pure scheduler entity. it represents a virtual cpu. when a thread is running, it always has a KSE associated with it. scheduler is free to assign a KSE to thread according thread priority, if thread priority is changed, KSE can be moved from one thread to another. When a ksegrp is created, there is always N KSEs created in the group. the N is the number of physical cpu in the current system. This makes it is possible that even an userland UTS is single CPU safe, threads in kernel still can execute on different cpu in parallel. Userland calls kse_create to add more upcall structures into ksegrp to increase concurrent in userland itself, kernel is not restricted by number of upcalls userland provides. The code hasn't been tested under SMP by author due to lack of hardware. Reviewed by: julian
635 lines
16 KiB
C
635 lines
16 KiB
C
/*
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* Copyright (c) 1995
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* The Regents of the University of California. All rights reserved.
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*
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* Copyright (C) 1997
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* John S. Dyson. All rights reserved.
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*
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* This code contains ideas from software contributed to Berkeley by
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* Avadis Tevanian, Jr., Michael Wayne Young, and the Mach Operating
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* System project at Carnegie-Mellon University.
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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_lock.c 8.18 (Berkeley) 5/21/95
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* $FreeBSD$
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*/
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#include <sys/param.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/lockmgr.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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/*
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* Locking primitives implementation.
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* Locks provide shared/exclusive sychronization.
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*/
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#define LOCK_WAIT_TIME 100
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#define LOCK_SAMPLE_WAIT 7
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#if defined(DIAGNOSTIC)
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#define LOCK_INLINE
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#else
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#define LOCK_INLINE __inline
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#endif
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#define LK_ALL (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE | \
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LK_SHARE_NONZERO | LK_WAIT_NONZERO)
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/*
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* Mutex array variables. Rather than each lockmgr lock having its own mutex,
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* share a fixed (at boot time) number of mutexes across all lockmgr locks in
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* order to keep sizeof(struct lock) down.
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*/
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int lock_mtx_valid;
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static struct mtx lock_mtx;
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static int acquire(struct lock **lkpp, int extflags, int wanted);
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static int apause(struct lock *lkp, int flags);
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static int acquiredrain(struct lock *lkp, int extflags) ;
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static void
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lockmgr_init(void *dummy __unused)
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{
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/*
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* Initialize the lockmgr protection mutex if it hasn't already been
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* done. Unless something changes about kernel startup order, VM
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* initialization will always cause this mutex to already be
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* initialized in a call to lockinit().
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*/
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if (lock_mtx_valid == 0) {
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mtx_init(&lock_mtx, "lockmgr", NULL, MTX_DEF);
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lock_mtx_valid = 1;
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}
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}
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SYSINIT(lmgrinit, SI_SUB_LOCK, SI_ORDER_FIRST, lockmgr_init, NULL)
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static LOCK_INLINE void
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sharelock(struct lock *lkp, int incr) {
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lkp->lk_flags |= LK_SHARE_NONZERO;
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lkp->lk_sharecount += incr;
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}
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static LOCK_INLINE void
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shareunlock(struct lock *lkp, int decr) {
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KASSERT(lkp->lk_sharecount >= decr, ("shareunlock: count < decr"));
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if (lkp->lk_sharecount == decr) {
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lkp->lk_flags &= ~LK_SHARE_NONZERO;
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if (lkp->lk_flags & (LK_WANT_UPGRADE | LK_WANT_EXCL)) {
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wakeup(lkp);
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}
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lkp->lk_sharecount = 0;
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} else {
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lkp->lk_sharecount -= decr;
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}
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}
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/*
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* This is the waitloop optimization.
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*/
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static int
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apause(struct lock *lkp, int flags)
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{
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#ifdef SMP
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int i, lock_wait;
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#endif
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if ((lkp->lk_flags & flags) == 0)
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return 0;
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#ifdef SMP
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for (lock_wait = LOCK_WAIT_TIME; lock_wait > 0; lock_wait--) {
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mtx_unlock(lkp->lk_interlock);
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for (i = LOCK_SAMPLE_WAIT; i > 0; i--)
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if ((lkp->lk_flags & flags) == 0)
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break;
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mtx_lock(lkp->lk_interlock);
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if ((lkp->lk_flags & flags) == 0)
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return 0;
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}
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#endif
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return 1;
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}
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static int
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acquire(struct lock **lkpp, int extflags, int wanted) {
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struct lock *lkp = *lkpp;
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int s, error;
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CTR3(KTR_LOCKMGR,
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"acquire(): lkp == %p, extflags == 0x%x, wanted == 0x%x\n",
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lkp, extflags, wanted);
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if ((extflags & LK_NOWAIT) && (lkp->lk_flags & wanted)) {
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return EBUSY;
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}
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if (((lkp->lk_flags | extflags) & LK_NOPAUSE) == 0) {
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error = apause(lkp, wanted);
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if (error == 0)
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return 0;
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}
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s = splhigh();
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while ((lkp->lk_flags & wanted) != 0) {
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lkp->lk_flags |= LK_WAIT_NONZERO;
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lkp->lk_waitcount++;
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error = msleep(lkp, lkp->lk_interlock, lkp->lk_prio,
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lkp->lk_wmesg,
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((extflags & LK_TIMELOCK) ? lkp->lk_timo : 0));
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if (lkp->lk_waitcount == 1) {
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lkp->lk_flags &= ~LK_WAIT_NONZERO;
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lkp->lk_waitcount = 0;
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} else {
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lkp->lk_waitcount--;
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}
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if (error) {
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splx(s);
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return error;
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}
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if (extflags & LK_SLEEPFAIL) {
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splx(s);
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return ENOLCK;
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}
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if (lkp->lk_newlock != NULL) {
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mtx_lock(lkp->lk_newlock->lk_interlock);
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mtx_unlock(lkp->lk_interlock);
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if (lkp->lk_waitcount == 0)
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wakeup((void *)(&lkp->lk_newlock));
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*lkpp = lkp = lkp->lk_newlock;
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}
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}
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splx(s);
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return 0;
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}
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/*
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* Set, change, or release a lock.
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*
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* Shared requests increment the shared count. Exclusive requests set the
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* LK_WANT_EXCL flag (preventing further shared locks), and wait for already
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* accepted shared locks and shared-to-exclusive upgrades to go away.
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*/
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int
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#ifndef DEBUG_LOCKS
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lockmgr(lkp, flags, interlkp, td)
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#else
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debuglockmgr(lkp, flags, interlkp, td, name, file, line)
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#endif
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struct lock *lkp;
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u_int flags;
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struct mtx *interlkp;
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struct thread *td;
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#ifdef DEBUG_LOCKS
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const char *name; /* Name of lock function */
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const char *file; /* Name of file call is from */
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int line; /* Line number in file */
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#endif
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{
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int error;
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struct thread *thr;
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int extflags, lockflags;
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CTR5(KTR_LOCKMGR,
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"lockmgr(): lkp == %p (lk_wmesg == \"%s\"), flags == 0x%x, "
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"interlkp == %p, td == %p", lkp, lkp->lk_wmesg, flags, interlkp, td);
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error = 0;
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if (td == NULL)
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thr = LK_KERNPROC;
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else
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thr = td;
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mtx_lock(lkp->lk_interlock);
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if (flags & LK_INTERLOCK) {
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mtx_assert(interlkp, MA_OWNED | MA_NOTRECURSED);
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mtx_unlock(interlkp);
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}
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if (panicstr != NULL) {
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mtx_unlock(lkp->lk_interlock);
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return (0);
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}
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extflags = (flags | lkp->lk_flags) & LK_EXTFLG_MASK;
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switch (flags & LK_TYPE_MASK) {
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case LK_SHARED:
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/*
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* If we are not the exclusive lock holder, we have to block
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* while there is an exclusive lock holder or while an
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* exclusive lock request or upgrade request is in progress.
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*
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* However, if TDF_DEADLKTREAT is set, we override exclusive
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* lock requests or upgrade requests ( but not the exclusive
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* lock itself ).
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*/
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if (lkp->lk_lockholder != thr) {
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lockflags = LK_HAVE_EXCL;
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mtx_lock_spin(&sched_lock);
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if (td != NULL && !(td->td_flags & TDF_DEADLKTREAT))
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lockflags |= LK_WANT_EXCL | LK_WANT_UPGRADE;
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mtx_unlock_spin(&sched_lock);
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error = acquire(&lkp, extflags, lockflags);
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if (error)
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break;
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sharelock(lkp, 1);
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#if defined(DEBUG_LOCKS)
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lkp->lk_slockholder = thr;
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lkp->lk_sfilename = file;
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lkp->lk_slineno = line;
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lkp->lk_slockername = name;
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#endif
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break;
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}
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/*
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* We hold an exclusive lock, so downgrade it to shared.
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* An alternative would be to fail with EDEADLK.
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*/
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sharelock(lkp, 1);
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/* FALLTHROUGH downgrade */
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case LK_DOWNGRADE:
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KASSERT(lkp->lk_lockholder == thr && lkp->lk_exclusivecount != 0,
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("lockmgr: not holding exclusive lock "
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"(owner thread (%p) != thread (%p), exlcnt (%d) != 0",
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lkp->lk_lockholder, thr, lkp->lk_exclusivecount));
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sharelock(lkp, lkp->lk_exclusivecount);
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lkp->lk_exclusivecount = 0;
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lkp->lk_flags &= ~LK_HAVE_EXCL;
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lkp->lk_lockholder = (struct thread *)LK_NOPROC;
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if (lkp->lk_waitcount)
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wakeup((void *)lkp);
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break;
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case LK_EXCLUPGRADE:
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/*
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* If another process is ahead of us to get an upgrade,
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* then we want to fail rather than have an intervening
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* exclusive access.
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*/
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if (lkp->lk_flags & LK_WANT_UPGRADE) {
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shareunlock(lkp, 1);
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error = EBUSY;
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break;
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}
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/* FALLTHROUGH normal upgrade */
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case LK_UPGRADE:
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/*
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* Upgrade a shared lock to an exclusive one. If another
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* shared lock has already requested an upgrade to an
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* exclusive lock, our shared lock is released and an
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* exclusive lock is requested (which will be granted
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* after the upgrade). If we return an error, the file
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* will always be unlocked.
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*/
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if ((lkp->lk_lockholder == thr) || (lkp->lk_sharecount <= 0))
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panic("lockmgr: upgrade exclusive lock");
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shareunlock(lkp, 1);
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/*
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* If we are just polling, check to see if we will block.
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*/
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if ((extflags & LK_NOWAIT) &&
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((lkp->lk_flags & LK_WANT_UPGRADE) ||
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lkp->lk_sharecount > 1)) {
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error = EBUSY;
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break;
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}
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if ((lkp->lk_flags & LK_WANT_UPGRADE) == 0) {
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/*
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* We are first shared lock to request an upgrade, so
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* request upgrade and wait for the shared count to
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* drop to zero, then take exclusive lock.
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*/
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lkp->lk_flags |= LK_WANT_UPGRADE;
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error = acquire(&lkp, extflags, LK_SHARE_NONZERO);
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lkp->lk_flags &= ~LK_WANT_UPGRADE;
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if (error)
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break;
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lkp->lk_flags |= LK_HAVE_EXCL;
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lkp->lk_lockholder = thr;
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if (lkp->lk_exclusivecount != 0)
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panic("lockmgr: non-zero exclusive count");
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lkp->lk_exclusivecount = 1;
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#if defined(DEBUG_LOCKS)
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lkp->lk_filename = file;
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lkp->lk_lineno = line;
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lkp->lk_lockername = name;
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#endif
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break;
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}
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/*
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* Someone else has requested upgrade. Release our shared
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* lock, awaken upgrade requestor if we are the last shared
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* lock, then request an exclusive lock.
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*/
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if ( (lkp->lk_flags & (LK_SHARE_NONZERO|LK_WAIT_NONZERO)) ==
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LK_WAIT_NONZERO)
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wakeup((void *)lkp);
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/* FALLTHROUGH exclusive request */
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case LK_EXCLUSIVE:
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if (lkp->lk_lockholder == thr && thr != LK_KERNPROC) {
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/*
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* Recursive lock.
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*/
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if ((extflags & (LK_NOWAIT | LK_CANRECURSE)) == 0)
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panic("lockmgr: locking against myself");
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if ((extflags & LK_CANRECURSE) != 0) {
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lkp->lk_exclusivecount++;
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break;
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}
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}
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/*
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* If we are just polling, check to see if we will sleep.
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*/
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if ((extflags & LK_NOWAIT) &&
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(lkp->lk_flags & (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE | LK_SHARE_NONZERO))) {
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error = EBUSY;
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break;
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}
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/*
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* Try to acquire the want_exclusive flag.
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*/
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error = acquire(&lkp, extflags, (LK_HAVE_EXCL | LK_WANT_EXCL));
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if (error)
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break;
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lkp->lk_flags |= LK_WANT_EXCL;
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/*
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* Wait for shared locks and upgrades to finish.
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*/
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error = acquire(&lkp, extflags, LK_WANT_UPGRADE | LK_SHARE_NONZERO);
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lkp->lk_flags &= ~LK_WANT_EXCL;
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if (error)
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break;
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lkp->lk_flags |= LK_HAVE_EXCL;
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lkp->lk_lockholder = thr;
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if (lkp->lk_exclusivecount != 0)
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panic("lockmgr: non-zero exclusive count");
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lkp->lk_exclusivecount = 1;
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#if defined(DEBUG_LOCKS)
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lkp->lk_filename = file;
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lkp->lk_lineno = line;
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lkp->lk_lockername = name;
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#endif
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break;
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case LK_RELEASE:
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if (lkp->lk_exclusivecount != 0) {
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if (lkp->lk_lockholder != thr &&
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lkp->lk_lockholder != LK_KERNPROC) {
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panic("lockmgr: thread %p, not %s %p unlocking",
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thr, "exclusive lock holder",
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lkp->lk_lockholder);
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}
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if (lkp->lk_exclusivecount == 1) {
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lkp->lk_flags &= ~LK_HAVE_EXCL;
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lkp->lk_lockholder = LK_NOPROC;
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lkp->lk_exclusivecount = 0;
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} else {
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lkp->lk_exclusivecount--;
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}
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} else if (lkp->lk_flags & LK_SHARE_NONZERO)
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shareunlock(lkp, 1);
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if (lkp->lk_flags & LK_WAIT_NONZERO)
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wakeup((void *)lkp);
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break;
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case LK_DRAIN:
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/*
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* Check that we do not already hold the lock, as it can
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* never drain if we do. Unfortunately, we have no way to
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* check for holding a shared lock, but at least we can
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* check for an exclusive one.
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*/
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if (lkp->lk_lockholder == thr)
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panic("lockmgr: draining against myself");
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error = acquiredrain(lkp, extflags);
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if (error)
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break;
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lkp->lk_flags |= LK_DRAINING | LK_HAVE_EXCL;
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lkp->lk_lockholder = thr;
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lkp->lk_exclusivecount = 1;
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#if defined(DEBUG_LOCKS)
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lkp->lk_filename = file;
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lkp->lk_lineno = line;
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lkp->lk_lockername = name;
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#endif
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break;
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default:
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mtx_unlock(lkp->lk_interlock);
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panic("lockmgr: unknown locktype request %d",
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flags & LK_TYPE_MASK);
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/* NOTREACHED */
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}
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if ((lkp->lk_flags & LK_WAITDRAIN) &&
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(lkp->lk_flags & (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE |
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LK_SHARE_NONZERO | LK_WAIT_NONZERO)) == 0) {
|
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lkp->lk_flags &= ~LK_WAITDRAIN;
|
|
wakeup((void *)&lkp->lk_flags);
|
|
}
|
|
mtx_unlock(lkp->lk_interlock);
|
|
return (error);
|
|
}
|
|
|
|
static int
|
|
acquiredrain(struct lock *lkp, int extflags) {
|
|
int error;
|
|
|
|
if ((extflags & LK_NOWAIT) && (lkp->lk_flags & LK_ALL)) {
|
|
return EBUSY;
|
|
}
|
|
|
|
error = apause(lkp, LK_ALL);
|
|
if (error == 0)
|
|
return 0;
|
|
|
|
while (lkp->lk_flags & LK_ALL) {
|
|
lkp->lk_flags |= LK_WAITDRAIN;
|
|
error = msleep(&lkp->lk_flags, lkp->lk_interlock, lkp->lk_prio,
|
|
lkp->lk_wmesg,
|
|
((extflags & LK_TIMELOCK) ? lkp->lk_timo : 0));
|
|
if (error)
|
|
return error;
|
|
if (extflags & LK_SLEEPFAIL) {
|
|
return ENOLCK;
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Transfer any waiting processes from one lock to another.
|
|
*/
|
|
void
|
|
transferlockers(from, to)
|
|
struct lock *from;
|
|
struct lock *to;
|
|
{
|
|
|
|
KASSERT(from != to, ("lock transfer to self"));
|
|
KASSERT((from->lk_flags&LK_WAITDRAIN) == 0, ("transfer draining lock"));
|
|
if (from->lk_waitcount == 0)
|
|
return;
|
|
from->lk_newlock = to;
|
|
wakeup((void *)from);
|
|
msleep(&from->lk_newlock, NULL, from->lk_prio, "lkxfer", 0);
|
|
from->lk_newlock = NULL;
|
|
from->lk_flags &= ~(LK_WANT_EXCL | LK_WANT_UPGRADE);
|
|
KASSERT(from->lk_waitcount == 0, ("active lock"));
|
|
}
|
|
|
|
|
|
/*
|
|
* Initialize a lock; required before use.
|
|
*/
|
|
void
|
|
lockinit(lkp, prio, wmesg, timo, flags)
|
|
struct lock *lkp;
|
|
int prio;
|
|
const char *wmesg;
|
|
int timo;
|
|
int flags;
|
|
{
|
|
CTR5(KTR_LOCKMGR, "lockinit(): lkp == %p, prio == %d, wmesg == \"%s\", "
|
|
"timo == %d, flags = 0x%x\n", lkp, prio, wmesg, timo, flags);
|
|
|
|
if (lock_mtx_valid == 0) {
|
|
mtx_init(&lock_mtx, "lockmgr", NULL, MTX_DEF);
|
|
lock_mtx_valid = 1;
|
|
}
|
|
/*
|
|
* XXX cleanup - make sure mtxpool is always initialized before
|
|
* this is ever called.
|
|
*/
|
|
if (mtx_pool_valid) {
|
|
mtx_lock(&lock_mtx);
|
|
lkp->lk_interlock = mtx_pool_alloc();
|
|
mtx_unlock(&lock_mtx);
|
|
} else {
|
|
lkp->lk_interlock = &lock_mtx;
|
|
}
|
|
lkp->lk_flags = (flags & LK_EXTFLG_MASK);
|
|
lkp->lk_sharecount = 0;
|
|
lkp->lk_waitcount = 0;
|
|
lkp->lk_exclusivecount = 0;
|
|
lkp->lk_prio = prio;
|
|
lkp->lk_wmesg = wmesg;
|
|
lkp->lk_timo = timo;
|
|
lkp->lk_lockholder = LK_NOPROC;
|
|
lkp->lk_newlock = NULL;
|
|
#ifdef DEBUG_LOCKS
|
|
lkp->lk_filename = "none";
|
|
lkp->lk_lockername = "never exclusive locked";
|
|
lkp->lk_lineno = 0;
|
|
lkp->lk_slockholder = LK_NOPROC;
|
|
lkp->lk_sfilename = "none";
|
|
lkp->lk_slockername = "never share locked";
|
|
lkp->lk_slineno = 0;
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* Destroy a lock.
|
|
*/
|
|
void
|
|
lockdestroy(lkp)
|
|
struct lock *lkp;
|
|
{
|
|
CTR2(KTR_LOCKMGR, "lockdestroy(): lkp == %p (lk_wmesg == \"%s\")",
|
|
lkp, lkp->lk_wmesg);
|
|
}
|
|
|
|
/*
|
|
* Determine the status of a lock.
|
|
*/
|
|
int
|
|
lockstatus(lkp, td)
|
|
struct lock *lkp;
|
|
struct thread *td;
|
|
{
|
|
int lock_type = 0;
|
|
|
|
mtx_lock(lkp->lk_interlock);
|
|
if (lkp->lk_exclusivecount != 0) {
|
|
if (td == NULL || lkp->lk_lockholder == td)
|
|
lock_type = LK_EXCLUSIVE;
|
|
else
|
|
lock_type = LK_EXCLOTHER;
|
|
} else if (lkp->lk_sharecount != 0)
|
|
lock_type = LK_SHARED;
|
|
mtx_unlock(lkp->lk_interlock);
|
|
return (lock_type);
|
|
}
|
|
|
|
/*
|
|
* Determine the number of holders of a lock.
|
|
*/
|
|
int
|
|
lockcount(lkp)
|
|
struct lock *lkp;
|
|
{
|
|
int count;
|
|
|
|
mtx_lock(lkp->lk_interlock);
|
|
count = lkp->lk_exclusivecount + lkp->lk_sharecount;
|
|
mtx_unlock(lkp->lk_interlock);
|
|
return (count);
|
|
}
|
|
|
|
/*
|
|
* Print out information about state of a lock. Used by VOP_PRINT
|
|
* routines to display status about contained locks.
|
|
*/
|
|
void
|
|
lockmgr_printinfo(lkp)
|
|
struct lock *lkp;
|
|
{
|
|
|
|
if (lkp->lk_sharecount)
|
|
printf(" lock type %s: SHARED (count %d)", lkp->lk_wmesg,
|
|
lkp->lk_sharecount);
|
|
else if (lkp->lk_flags & LK_HAVE_EXCL)
|
|
printf(" lock type %s: EXCL (count %d) by thread %p",
|
|
lkp->lk_wmesg, lkp->lk_exclusivecount, lkp->lk_lockholder);
|
|
if (lkp->lk_waitcount > 0)
|
|
printf(" with %d pending", lkp->lk_waitcount);
|
|
}
|