/* $NetBSD: kern_lock.c,v 1.92 2005/12/27 04:06:46 chs Exp $ */ /*- * Copyright (c) 1999, 2000 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility, * NASA Ames Research Center. * * This code is derived from software contributed to The NetBSD Foundation * by Ross Harvey. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the NetBSD * Foundation, Inc. and its contributors. * 4. Neither the name of The NetBSD Foundation nor the names of its * contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ /* * Copyright (c) 1995 * The Regents of the University of California. All rights reserved. * * This code contains ideas from software contributed to Berkeley by * Avadis Tevanian, Jr., Michael Wayne Young, and the Mach Operating * System project at Carnegie-Mellon University. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)kern_lock.c 8.18 (Berkeley) 5/21/95 */ #include __KERNEL_RCSID(0, "$NetBSD: kern_lock.c,v 1.92 2005/12/27 04:06:46 chs Exp $"); #include "opt_multiprocessor.h" #include "opt_lockdebug.h" #include "opt_ddb.h" #include #include #include #include #include #if defined(LOCKDEBUG) #include /* * note that stdarg.h and the ansi style va_start macro is used for both * ansi and traditional c compiles. * XXX: this requires that stdarg.h define: va_alist and va_dcl */ #include void lock_printf(const char *fmt, ...) __attribute__((__format__(__printf__,1,2))); static int acquire(volatile struct lock **, int *, int, int, int); int lock_debug_syslog = 0; /* defaults to printf, but can be patched */ #ifdef DDB #include #include #include #include #endif #endif /* defined(LOCKDEBUG) */ #if defined(MULTIPROCESSOR) struct simplelock kernel_lock; #endif /* * Locking primitives implementation. * Locks provide shared/exclusive synchronization. */ #if defined(LOCKDEBUG) || defined(DIAGNOSTIC) /* { */ #if defined(MULTIPROCESSOR) /* { */ #define COUNT_CPU(cpu_id, x) \ curcpu()->ci_spin_locks += (x) #else u_long spin_locks; #define COUNT_CPU(cpu_id, x) spin_locks += (x) #endif /* MULTIPROCESSOR */ /* } */ #define COUNT(lkp, l, cpu_id, x) \ do { \ if ((lkp)->lk_flags & LK_SPIN) \ COUNT_CPU((cpu_id), (x)); \ else \ (l)->l_locks += (x); \ } while (/*CONSTCOND*/0) #else #define COUNT(lkp, p, cpu_id, x) #define COUNT_CPU(cpu_id, x) #endif /* LOCKDEBUG || DIAGNOSTIC */ /* } */ #ifndef SPINLOCK_SPIN_HOOK /* from */ #define SPINLOCK_SPIN_HOOK /* nothing */ #endif #define INTERLOCK_ACQUIRE(lkp, flags, s) \ do { \ if ((flags) & LK_SPIN) \ s = spllock(); \ simple_lock(&(lkp)->lk_interlock); \ } while (/*CONSTCOND*/ 0) #define INTERLOCK_RELEASE(lkp, flags, s) \ do { \ simple_unlock(&(lkp)->lk_interlock); \ if ((flags) & LK_SPIN) \ splx(s); \ } while (/*CONSTCOND*/ 0) #ifdef DDB /* { */ #if defined(MULTIPROCESSOR) || defined(LOCKDEBUG) int simple_lock_debugger = 1; /* more serious on MP */ #else int simple_lock_debugger = 0; #endif #define SLOCK_DEBUGGER() if (simple_lock_debugger) Debugger() #define SLOCK_TRACE() \ db_stack_trace_print((db_expr_t)__builtin_frame_address(0), \ TRUE, 65535, "", lock_printf); #else #define SLOCK_DEBUGGER() /* nothing */ #define SLOCK_TRACE() /* nothing */ #endif /* } */ #if defined(LOCKDEBUG) #if defined(DDB) #define SPINLOCK_SPINCHECK_DEBUGGER Debugger() #else #define SPINLOCK_SPINCHECK_DEBUGGER /* nothing */ #endif #define SPINLOCK_SPINCHECK_DECL \ /* 32-bits of count -- wrap constitutes a "spinout" */ \ uint32_t __spinc = 0 #define SPINLOCK_SPINCHECK \ do { \ if (++__spinc == 0) { \ lock_printf("LK_SPIN spinout, excl %d, share %d\n", \ lkp->lk_exclusivecount, lkp->lk_sharecount); \ if (lkp->lk_exclusivecount) \ lock_printf("held by CPU %lu\n", \ (u_long) lkp->lk_cpu); \ if (lkp->lk_lock_file) \ lock_printf("last locked at %s:%d\n", \ lkp->lk_lock_file, lkp->lk_lock_line); \ if (lkp->lk_unlock_file) \ lock_printf("last unlocked at %s:%d\n", \ lkp->lk_unlock_file, lkp->lk_unlock_line); \ SLOCK_TRACE(); \ SPINLOCK_SPINCHECK_DEBUGGER; \ } \ } while (/*CONSTCOND*/ 0) #else #define SPINLOCK_SPINCHECK_DECL /* nothing */ #define SPINLOCK_SPINCHECK /* nothing */ #endif /* LOCKDEBUG && DDB */ /* * Acquire a resource. */ static int acquire(volatile struct lock **lkpp, int *s, int extflags, int drain, int wanted) { int error; volatile struct lock *lkp = *lkpp; KASSERT(drain || (wanted & LK_WAIT_NONZERO) == 0); if (extflags & LK_SPIN) { int interlocked; SPINLOCK_SPINCHECK_DECL; if (!drain) { lkp->lk_waitcount++; lkp->lk_flags |= LK_WAIT_NONZERO; } for (interlocked = 1;;) { SPINLOCK_SPINCHECK; if ((lkp->lk_flags & wanted) != 0) { if (interlocked) { INTERLOCK_RELEASE(lkp, LK_SPIN, *s); interlocked = 0; } SPINLOCK_SPIN_HOOK; } else if (interlocked) { break; } else { INTERLOCK_ACQUIRE(lkp, LK_SPIN, *s); interlocked = 1; } } if (!drain) { lkp->lk_waitcount--; if (lkp->lk_waitcount == 0) lkp->lk_flags &= ~LK_WAIT_NONZERO; } KASSERT((lkp->lk_flags & wanted) == 0); error = 0; /* sanity */ } else { for (error = 0; (lkp->lk_flags & wanted) != 0; ) { if (drain) lkp->lk_flags |= LK_WAITDRAIN; else { lkp->lk_waitcount++; lkp->lk_flags |= LK_WAIT_NONZERO; } /* XXX Cast away volatile. */ error = ltsleep(drain ? (volatile const void *)&lkp->lk_flags : (volatile const void *)lkp, lkp->lk_prio, lkp->lk_wmesg, lkp->lk_timo, &lkp->lk_interlock); if (!drain) { lkp->lk_waitcount--; if (lkp->lk_waitcount == 0) lkp->lk_flags &= ~LK_WAIT_NONZERO; } if (error) break; if (extflags & LK_SLEEPFAIL) { error = ENOLCK; break; } if (lkp->lk_newlock != NULL) { simple_lock(&lkp->lk_newlock->lk_interlock); simple_unlock(&lkp->lk_interlock); if (lkp->lk_waitcount == 0) wakeup(&lkp->lk_newlock); *lkpp = lkp = lkp->lk_newlock; } } } return error; } #define SETHOLDER(lkp, pid, lid, cpu_id) \ do { \ if ((lkp)->lk_flags & LK_SPIN) \ (lkp)->lk_cpu = cpu_id; \ else { \ (lkp)->lk_lockholder = pid; \ (lkp)->lk_locklwp = lid; \ } \ } while (/*CONSTCOND*/0) #define WEHOLDIT(lkp, pid, lid, cpu_id) \ (((lkp)->lk_flags & LK_SPIN) != 0 ? \ ((lkp)->lk_cpu == (cpu_id)) : \ ((lkp)->lk_lockholder == (pid) && (lkp)->lk_locklwp == (lid))) #define WAKEUP_WAITER(lkp) \ do { \ if (((lkp)->lk_flags & (LK_SPIN | LK_WAIT_NONZERO)) == \ LK_WAIT_NONZERO) { \ wakeup((lkp)); \ } \ } while (/*CONSTCOND*/0) #if defined(LOCKDEBUG) /* { */ #if defined(MULTIPROCESSOR) /* { */ struct simplelock spinlock_list_slock = SIMPLELOCK_INITIALIZER; #define SPINLOCK_LIST_LOCK() \ __cpu_simple_lock(&spinlock_list_slock.lock_data) #define SPINLOCK_LIST_UNLOCK() \ __cpu_simple_unlock(&spinlock_list_slock.lock_data) #else #define SPINLOCK_LIST_LOCK() /* nothing */ #define SPINLOCK_LIST_UNLOCK() /* nothing */ #endif /* MULTIPROCESSOR */ /* } */ _TAILQ_HEAD(, struct lock, volatile) spinlock_list = TAILQ_HEAD_INITIALIZER(spinlock_list); #define HAVEIT(lkp) \ do { \ if ((lkp)->lk_flags & LK_SPIN) { \ int sp = spllock(); \ SPINLOCK_LIST_LOCK(); \ TAILQ_INSERT_TAIL(&spinlock_list, (lkp), lk_list); \ SPINLOCK_LIST_UNLOCK(); \ splx(sp); \ } \ } while (/*CONSTCOND*/0) #define DONTHAVEIT(lkp) \ do { \ if ((lkp)->lk_flags & LK_SPIN) { \ int sp = spllock(); \ SPINLOCK_LIST_LOCK(); \ TAILQ_REMOVE(&spinlock_list, (lkp), lk_list); \ SPINLOCK_LIST_UNLOCK(); \ splx(sp); \ } \ } while (/*CONSTCOND*/0) #else #define HAVEIT(lkp) /* nothing */ #define DONTHAVEIT(lkp) /* nothing */ #endif /* LOCKDEBUG */ /* } */ #if defined(LOCKDEBUG) /* * Lock debug printing routine; can be configured to print to console * or log to syslog. */ void lock_printf(const char *fmt, ...) { char b[150]; va_list ap; va_start(ap, fmt); if (lock_debug_syslog) vlog(LOG_DEBUG, fmt, ap); else { vsnprintf(b, sizeof(b), fmt, ap); printf_nolog("%s", b); } va_end(ap); } #endif /* LOCKDEBUG */ /* * Transfer any waiting processes from one lock to another. */ void transferlockers(struct lock *from, struct lock *to) { KASSERT(from != to); KASSERT((from->lk_flags & LK_WAITDRAIN) == 0); if (from->lk_waitcount == 0) return; from->lk_newlock = to; wakeup((void *)from); tsleep((void *)&from->lk_newlock, from->lk_prio, "lkxfer", 0); from->lk_newlock = NULL; from->lk_flags &= ~(LK_WANT_EXCL | LK_WANT_UPGRADE); KASSERT(from->lk_waitcount == 0); } /* * Initialize a lock; required before use. */ void lockinit(struct lock *lkp, int prio, const char *wmesg, int timo, int flags) { memset(lkp, 0, sizeof(struct lock)); simple_lock_init(&lkp->lk_interlock); lkp->lk_flags = flags & LK_EXTFLG_MASK; if (flags & LK_SPIN) lkp->lk_cpu = LK_NOCPU; else { lkp->lk_lockholder = LK_NOPROC; lkp->lk_newlock = NULL; lkp->lk_prio = prio; lkp->lk_timo = timo; } lkp->lk_wmesg = wmesg; /* just a name for spin locks */ #if defined(LOCKDEBUG) lkp->lk_lock_file = NULL; lkp->lk_unlock_file = NULL; #endif } /* * Determine the status of a lock. */ int lockstatus(struct lock *lkp) { int s = 0; /* XXX: gcc */ int lock_type = 0; struct lwp *l = curlwp; /* XXX */ pid_t pid; lwpid_t lid; cpuid_t cpu_num; if ((lkp->lk_flags & LK_SPIN) || l == NULL) { cpu_num = cpu_number(); pid = LK_KERNPROC; lid = 0; } else { cpu_num = LK_NOCPU; pid = l->l_proc->p_pid; lid = l->l_lid; } INTERLOCK_ACQUIRE(lkp, lkp->lk_flags, s); if (lkp->lk_exclusivecount != 0) { if (WEHOLDIT(lkp, pid, lid, cpu_num)) lock_type = LK_EXCLUSIVE; else lock_type = LK_EXCLOTHER; } else if (lkp->lk_sharecount != 0) lock_type = LK_SHARED; INTERLOCK_RELEASE(lkp, lkp->lk_flags, s); return (lock_type); } #if defined(LOCKDEBUG) /* * Make sure no spin locks are held by a CPU that is about * to context switch. */ void spinlock_switchcheck(void) { u_long cnt; int s; s = spllock(); #if defined(MULTIPROCESSOR) cnt = curcpu()->ci_spin_locks; #else cnt = spin_locks; #endif splx(s); if (cnt != 0) panic("spinlock_switchcheck: CPU %lu has %lu spin locks", (u_long) cpu_number(), cnt); } #endif /* LOCKDEBUG */ /* * Locks and IPLs (interrupt priority levels): * * Locks which may be taken from interrupt context must be handled * very carefully; you must spl to the highest IPL where the lock * is needed before acquiring the lock. * * It is also important to avoid deadlock, since certain (very high * priority) interrupts are often needed to keep the system as a whole * from deadlocking, and must not be blocked while you are spinning * waiting for a lower-priority lock. * * In addition, the lock-debugging hooks themselves need to use locks! * * A raw __cpu_simple_lock may be used from interrupts are long as it * is acquired and held at a single IPL. * * A simple_lock (which is a __cpu_simple_lock wrapped with some * debugging hooks) may be used at or below spllock(), which is * typically at or just below splhigh() (i.e. blocks everything * but certain machine-dependent extremely high priority interrupts). * * spinlockmgr spinlocks should be used at or below splsched(). * * Some platforms may have interrupts of higher priority than splsched(), * including hard serial interrupts, inter-processor interrupts, and * kernel debugger traps. */ /* * XXX XXX kludge around another kludge.. * * vfs_shutdown() may be called from interrupt context, either as a result * of a panic, or from the debugger. It proceeds to call * sys_sync(&proc0, ...), pretending its running on behalf of proc0 * * We would like to make an attempt to sync the filesystems in this case, so * if this happens, we treat attempts to acquire locks specially. * All locks are acquired on behalf of proc0. * * If we've already paniced, we don't block waiting for locks, but * just barge right ahead since we're already going down in flames. */ /* * Set, change, or release a lock. * * Shared requests increment the shared count. Exclusive requests set the * LK_WANT_EXCL flag (preventing further shared locks), and wait for already * accepted shared locks and shared-to-exclusive upgrades to go away. */ int #if defined(LOCKDEBUG) _lockmgr(volatile struct lock *lkp, u_int flags, struct simplelock *interlkp, const char *file, int line) #else lockmgr(volatile struct lock *lkp, u_int flags, struct simplelock *interlkp) #endif { int error; pid_t pid; lwpid_t lid; int extflags; cpuid_t cpu_num; struct lwp *l = curlwp; int lock_shutdown_noblock = 0; int s = 0; error = 0; /* LK_RETRY is for vn_lock, not for lockmgr. */ KASSERT((flags & LK_RETRY) == 0); INTERLOCK_ACQUIRE(lkp, lkp->lk_flags, s); if (flags & LK_INTERLOCK) simple_unlock(interlkp); extflags = (flags | lkp->lk_flags) & LK_EXTFLG_MASK; #ifdef DIAGNOSTIC /* { */ /* * Don't allow spins on sleep locks and don't allow sleeps * on spin locks. */ if ((flags ^ lkp->lk_flags) & LK_SPIN) panic("lockmgr: sleep/spin mismatch"); #endif /* } */ if (extflags & LK_SPIN) { pid = LK_KERNPROC; lid = 0; } else { if (l == NULL) { if (!doing_shutdown) { panic("lockmgr: no context"); } else { l = &lwp0; if (panicstr && (!(flags & LK_NOWAIT))) { flags |= LK_NOWAIT; lock_shutdown_noblock = 1; } } } lid = l->l_lid; pid = l->l_proc->p_pid; } cpu_num = cpu_number(); /* * Once a lock has drained, the LK_DRAINING flag is set and an * exclusive lock is returned. The only valid operation thereafter * is a single release of that exclusive lock. This final release * clears the LK_DRAINING flag and sets the LK_DRAINED flag. Any * further requests of any sort will result in a panic. The bits * selected for these two flags are chosen so that they will be set * in memory that is freed (freed memory is filled with 0xdeadbeef). * The final release is permitted to give a new lease on life to * the lock by specifying LK_REENABLE. */ if (lkp->lk_flags & (LK_DRAINING|LK_DRAINED)) { #ifdef DIAGNOSTIC /* { */ if (lkp->lk_flags & LK_DRAINED) panic("lockmgr: using decommissioned lock"); if ((flags & LK_TYPE_MASK) != LK_RELEASE || WEHOLDIT(lkp, pid, lid, cpu_num) == 0) panic("lockmgr: non-release on draining lock: %d", flags & LK_TYPE_MASK); #endif /* DIAGNOSTIC */ /* } */ lkp->lk_flags &= ~LK_DRAINING; if ((flags & LK_REENABLE) == 0) lkp->lk_flags |= LK_DRAINED; } switch (flags & LK_TYPE_MASK) { case LK_SHARED: if (WEHOLDIT(lkp, pid, lid, cpu_num) == 0) { /* * If just polling, check to see if we will block. */ if ((extflags & LK_NOWAIT) && (lkp->lk_flags & (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE))) { error = EBUSY; break; } /* * Wait for exclusive locks and upgrades to clear. */ error = acquire(&lkp, &s, extflags, 0, LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE); if (error) break; lkp->lk_sharecount++; lkp->lk_flags |= LK_SHARE_NONZERO; COUNT(lkp, l, cpu_num, 1); break; } /* * We hold an exclusive lock, so downgrade it to shared. * An alternative would be to fail with EDEADLK. */ lkp->lk_sharecount++; lkp->lk_flags |= LK_SHARE_NONZERO; COUNT(lkp, l, cpu_num, 1); /* fall into downgrade */ case LK_DOWNGRADE: if (WEHOLDIT(lkp, pid, lid, cpu_num) == 0 || lkp->lk_exclusivecount == 0) panic("lockmgr: not holding exclusive lock"); lkp->lk_sharecount += lkp->lk_exclusivecount; lkp->lk_flags |= LK_SHARE_NONZERO; lkp->lk_exclusivecount = 0; lkp->lk_recurselevel = 0; lkp->lk_flags &= ~LK_HAVE_EXCL; SETHOLDER(lkp, LK_NOPROC, 0, LK_NOCPU); #if defined(LOCKDEBUG) lkp->lk_unlock_file = file; lkp->lk_unlock_line = line; #endif DONTHAVEIT(lkp); WAKEUP_WAITER(lkp); break; case LK_EXCLUPGRADE: /* * If another process is ahead of us to get an upgrade, * then we want to fail rather than have an intervening * exclusive access. */ if (lkp->lk_flags & LK_WANT_UPGRADE) { lkp->lk_sharecount--; if (lkp->lk_sharecount == 0) lkp->lk_flags &= ~LK_SHARE_NONZERO; COUNT(lkp, l, cpu_num, -1); error = EBUSY; break; } /* fall into normal upgrade */ case LK_UPGRADE: /* * Upgrade a shared lock to an exclusive one. If another * shared lock has already requested an upgrade to an * exclusive lock, our shared lock is released and an * exclusive lock is requested (which will be granted * after the upgrade). If we return an error, the file * will always be unlocked. */ if (WEHOLDIT(lkp, pid, lid, cpu_num) || lkp->lk_sharecount <= 0) panic("lockmgr: upgrade exclusive lock"); lkp->lk_sharecount--; if (lkp->lk_sharecount == 0) lkp->lk_flags &= ~LK_SHARE_NONZERO; COUNT(lkp, l, cpu_num, -1); /* * If we are just polling, check to see if we will block. */ if ((extflags & LK_NOWAIT) && ((lkp->lk_flags & LK_WANT_UPGRADE) || lkp->lk_sharecount > 1)) { error = EBUSY; break; } if ((lkp->lk_flags & LK_WANT_UPGRADE) == 0) { /* * We are first shared lock to request an upgrade, so * request upgrade and wait for the shared count to * drop to zero, then take exclusive lock. */ lkp->lk_flags |= LK_WANT_UPGRADE; error = acquire(&lkp, &s, extflags, 0, LK_SHARE_NONZERO); lkp->lk_flags &= ~LK_WANT_UPGRADE; if (error) { WAKEUP_WAITER(lkp); break; } lkp->lk_flags |= LK_HAVE_EXCL; SETHOLDER(lkp, pid, lid, cpu_num); #if defined(LOCKDEBUG) lkp->lk_lock_file = file; lkp->lk_lock_line = line; #endif HAVEIT(lkp); if (lkp->lk_exclusivecount != 0) panic("lockmgr: non-zero exclusive count"); lkp->lk_exclusivecount = 1; if (extflags & LK_SETRECURSE) lkp->lk_recurselevel = 1; COUNT(lkp, l, cpu_num, 1); break; } /* * Someone else has requested upgrade. Release our shared * lock, awaken upgrade requestor if we are the last shared * lock, then request an exclusive lock. */ if (lkp->lk_sharecount == 0) WAKEUP_WAITER(lkp); /* fall into exclusive request */ case LK_EXCLUSIVE: if (WEHOLDIT(lkp, pid, lid, cpu_num)) { /* * Recursive lock. */ if ((extflags & LK_CANRECURSE) == 0 && lkp->lk_recurselevel == 0) { if (extflags & LK_RECURSEFAIL) { error = EDEADLK; break; } else panic("lockmgr: locking against myself"); } lkp->lk_exclusivecount++; if (extflags & LK_SETRECURSE && lkp->lk_recurselevel == 0) lkp->lk_recurselevel = lkp->lk_exclusivecount; COUNT(lkp, l, cpu_num, 1); break; } /* * If we are just polling, check to see if we will sleep. */ if ((extflags & LK_NOWAIT) && (lkp->lk_flags & (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE | LK_SHARE_NONZERO))) { error = EBUSY; break; } /* * Try to acquire the want_exclusive flag. */ error = acquire(&lkp, &s, extflags, 0, LK_HAVE_EXCL | LK_WANT_EXCL); if (error) break; lkp->lk_flags |= LK_WANT_EXCL; /* * Wait for shared locks and upgrades to finish. */ error = acquire(&lkp, &s, extflags, 0, LK_HAVE_EXCL | LK_WANT_UPGRADE | LK_SHARE_NONZERO); lkp->lk_flags &= ~LK_WANT_EXCL; if (error) { WAKEUP_WAITER(lkp); break; } lkp->lk_flags |= LK_HAVE_EXCL; SETHOLDER(lkp, pid, lid, cpu_num); #if defined(LOCKDEBUG) lkp->lk_lock_file = file; lkp->lk_lock_line = line; #endif HAVEIT(lkp); if (lkp->lk_exclusivecount != 0) panic("lockmgr: non-zero exclusive count"); lkp->lk_exclusivecount = 1; if (extflags & LK_SETRECURSE) lkp->lk_recurselevel = 1; COUNT(lkp, l, cpu_num, 1); break; case LK_RELEASE: if (lkp->lk_exclusivecount != 0) { if (WEHOLDIT(lkp, pid, lid, cpu_num) == 0) { if (lkp->lk_flags & LK_SPIN) { panic("lockmgr: processor %lu, not " "exclusive lock holder %lu " "unlocking", cpu_num, lkp->lk_cpu); } else { panic("lockmgr: pid %d, not " "exclusive lock holder %d " "unlocking", pid, lkp->lk_lockholder); } } if (lkp->lk_exclusivecount == lkp->lk_recurselevel) lkp->lk_recurselevel = 0; lkp->lk_exclusivecount--; COUNT(lkp, l, cpu_num, -1); if (lkp->lk_exclusivecount == 0) { lkp->lk_flags &= ~LK_HAVE_EXCL; SETHOLDER(lkp, LK_NOPROC, 0, LK_NOCPU); #if defined(LOCKDEBUG) lkp->lk_unlock_file = file; lkp->lk_unlock_line = line; #endif DONTHAVEIT(lkp); } } else if (lkp->lk_sharecount != 0) { lkp->lk_sharecount--; if (lkp->lk_sharecount == 0) lkp->lk_flags &= ~LK_SHARE_NONZERO; COUNT(lkp, l, cpu_num, -1); } #ifdef DIAGNOSTIC else panic("lockmgr: release of unlocked lock!"); #endif WAKEUP_WAITER(lkp); break; case LK_DRAIN: /* * Check that we do not already hold the lock, as it can * never drain if we do. Unfortunately, we have no way to * check for holding a shared lock, but at least we can * check for an exclusive one. */ if (WEHOLDIT(lkp, pid, lid, cpu_num)) panic("lockmgr: draining against myself"); /* * If we are just polling, check to see if we will sleep. */ if ((extflags & LK_NOWAIT) && (lkp->lk_flags & (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE | LK_SHARE_NONZERO | LK_WAIT_NONZERO))) { error = EBUSY; break; } error = acquire(&lkp, &s, extflags, 1, LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE | LK_SHARE_NONZERO | LK_WAIT_NONZERO); if (error) break; lkp->lk_flags |= LK_DRAINING | LK_HAVE_EXCL; SETHOLDER(lkp, pid, lid, cpu_num); #if defined(LOCKDEBUG) lkp->lk_lock_file = file; lkp->lk_lock_line = line; #endif HAVEIT(lkp); lkp->lk_exclusivecount = 1; /* XXX unlikely that we'd want this */ if (extflags & LK_SETRECURSE) lkp->lk_recurselevel = 1; COUNT(lkp, l, cpu_num, 1); break; default: INTERLOCK_RELEASE(lkp, lkp->lk_flags, s); panic("lockmgr: unknown locktype request %d", flags & LK_TYPE_MASK); /* NOTREACHED */ } if ((lkp->lk_flags & (LK_WAITDRAIN|LK_SPIN)) == LK_WAITDRAIN && ((lkp->lk_flags & (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE | LK_SHARE_NONZERO | LK_WAIT_NONZERO)) == 0)) { lkp->lk_flags &= ~LK_WAITDRAIN; wakeup(&lkp->lk_flags); } /* * Note that this panic will be a recursive panic, since * we only set lock_shutdown_noblock above if panicstr != NULL. */ if (error && lock_shutdown_noblock) panic("lockmgr: deadlock (see previous panic)"); INTERLOCK_RELEASE(lkp, lkp->lk_flags, s); return (error); } /* * For a recursive spinlock held one or more times by the current CPU, * release all N locks, and return N. * Intended for use in mi_switch() shortly before context switching. */ int #if defined(LOCKDEBUG) _spinlock_release_all(volatile struct lock *lkp, const char *file, int line) #else spinlock_release_all(volatile struct lock *lkp) #endif { int s, count; cpuid_t cpu_num; KASSERT(lkp->lk_flags & LK_SPIN); INTERLOCK_ACQUIRE(lkp, LK_SPIN, s); cpu_num = cpu_number(); count = lkp->lk_exclusivecount; if (count != 0) { #ifdef DIAGNOSTIC if (WEHOLDIT(lkp, 0, 0, cpu_num) == 0) { panic("spinlock_release_all: processor %lu, not " "exclusive lock holder %lu " "unlocking", (long)cpu_num, lkp->lk_cpu); } #endif lkp->lk_recurselevel = 0; lkp->lk_exclusivecount = 0; COUNT_CPU(cpu_num, -count); lkp->lk_flags &= ~LK_HAVE_EXCL; SETHOLDER(lkp, LK_NOPROC, 0, LK_NOCPU); #if defined(LOCKDEBUG) lkp->lk_unlock_file = file; lkp->lk_unlock_line = line; #endif DONTHAVEIT(lkp); } #ifdef DIAGNOSTIC else if (lkp->lk_sharecount != 0) panic("spinlock_release_all: release of shared lock!"); else panic("spinlock_release_all: release of unlocked lock!"); #endif INTERLOCK_RELEASE(lkp, LK_SPIN, s); return (count); } /* * For a recursive spinlock held one or more times by the current CPU, * release all N locks, and return N. * Intended for use in mi_switch() right after resuming execution. */ void #if defined(LOCKDEBUG) _spinlock_acquire_count(volatile struct lock *lkp, int count, const char *file, int line) #else spinlock_acquire_count(volatile struct lock *lkp, int count) #endif { int s, error; cpuid_t cpu_num; KASSERT(lkp->lk_flags & LK_SPIN); INTERLOCK_ACQUIRE(lkp, LK_SPIN, s); cpu_num = cpu_number(); #ifdef DIAGNOSTIC if (WEHOLDIT(lkp, LK_NOPROC, 0, cpu_num)) panic("spinlock_acquire_count: processor %lu already holds lock", (long)cpu_num); #endif /* * Try to acquire the want_exclusive flag. */ error = acquire(&lkp, &s, LK_SPIN, 0, LK_HAVE_EXCL | LK_WANT_EXCL); lkp->lk_flags |= LK_WANT_EXCL; /* * Wait for shared locks and upgrades to finish. */ error = acquire(&lkp, &s, LK_SPIN, 0, LK_HAVE_EXCL | LK_SHARE_NONZERO | LK_WANT_UPGRADE); lkp->lk_flags &= ~LK_WANT_EXCL; lkp->lk_flags |= LK_HAVE_EXCL; SETHOLDER(lkp, LK_NOPROC, 0, cpu_num); #if defined(LOCKDEBUG) lkp->lk_lock_file = file; lkp->lk_lock_line = line; #endif HAVEIT(lkp); if (lkp->lk_exclusivecount != 0) panic("lockmgr: non-zero exclusive count"); lkp->lk_exclusivecount = count; lkp->lk_recurselevel = 1; COUNT_CPU(cpu_num, count); INTERLOCK_RELEASE(lkp, lkp->lk_flags, s); } /* * Print out information about state of a lock. Used by VOP_PRINT * routines to display ststus about contained locks. */ void lockmgr_printinfo(volatile 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 ", lkp->lk_wmesg, lkp->lk_exclusivecount); if (lkp->lk_flags & LK_SPIN) printf("processor %lu", lkp->lk_cpu); else printf("pid %d.%d", lkp->lk_lockholder, lkp->lk_locklwp); } else printf(" not locked"); if ((lkp->lk_flags & LK_SPIN) == 0 && lkp->lk_waitcount > 0) printf(" with %d pending", lkp->lk_waitcount); } #if defined(LOCKDEBUG) /* { */ _TAILQ_HEAD(, struct simplelock, volatile) simplelock_list = TAILQ_HEAD_INITIALIZER(simplelock_list); #if defined(MULTIPROCESSOR) /* { */ struct simplelock simplelock_list_slock = SIMPLELOCK_INITIALIZER; #define SLOCK_LIST_LOCK() \ __cpu_simple_lock(&simplelock_list_slock.lock_data) #define SLOCK_LIST_UNLOCK() \ __cpu_simple_unlock(&simplelock_list_slock.lock_data) #define SLOCK_COUNT(x) \ curcpu()->ci_simple_locks += (x) #else u_long simple_locks; #define SLOCK_LIST_LOCK() /* nothing */ #define SLOCK_LIST_UNLOCK() /* nothing */ #define SLOCK_COUNT(x) simple_locks += (x) #endif /* MULTIPROCESSOR */ /* } */ #ifdef MULTIPROCESSOR #define SLOCK_MP() lock_printf("on CPU %ld\n", \ (u_long) cpu_number()) #else #define SLOCK_MP() /* nothing */ #endif #define SLOCK_WHERE(str, alp, id, l) \ do { \ lock_printf("\n"); \ lock_printf(str); \ lock_printf("lock: %p, currently at: %s:%d\n", (alp), (id), (l)); \ SLOCK_MP(); \ if ((alp)->lock_file != NULL) \ lock_printf("last locked: %s:%d\n", (alp)->lock_file, \ (alp)->lock_line); \ if ((alp)->unlock_file != NULL) \ lock_printf("last unlocked: %s:%d\n", (alp)->unlock_file, \ (alp)->unlock_line); \ SLOCK_TRACE() \ SLOCK_DEBUGGER(); \ } while (/*CONSTCOND*/0) /* * Simple lock functions so that the debugger can see from whence * they are being called. */ void simple_lock_init(volatile struct simplelock *alp) { #if defined(MULTIPROCESSOR) /* { */ __cpu_simple_lock_init(&alp->lock_data); #else alp->lock_data = __SIMPLELOCK_UNLOCKED; #endif /* } */ alp->lock_file = NULL; alp->lock_line = 0; alp->unlock_file = NULL; alp->unlock_line = 0; alp->lock_holder = LK_NOCPU; } void _simple_lock(volatile struct simplelock *alp, const char *id, int l) { cpuid_t cpu_num = cpu_number(); int s; s = spllock(); /* * MULTIPROCESSOR case: This is `safe' since if it's not us, we * don't take any action, and just fall into the normal spin case. */ if (alp->lock_data == __SIMPLELOCK_LOCKED) { #if defined(MULTIPROCESSOR) /* { */ if (alp->lock_holder == cpu_num) { SLOCK_WHERE("simple_lock: locking against myself\n", alp, id, l); goto out; } #else SLOCK_WHERE("simple_lock: lock held\n", alp, id, l); goto out; #endif /* MULTIPROCESSOR */ /* } */ } #if defined(MULTIPROCESSOR) /* { */ /* Acquire the lock before modifying any fields. */ splx(s); __cpu_simple_lock(&alp->lock_data); s = spllock(); #else alp->lock_data = __SIMPLELOCK_LOCKED; #endif /* } */ if (alp->lock_holder != LK_NOCPU) { SLOCK_WHERE("simple_lock: uninitialized lock\n", alp, id, l); } alp->lock_file = id; alp->lock_line = l; alp->lock_holder = cpu_num; SLOCK_LIST_LOCK(); TAILQ_INSERT_TAIL(&simplelock_list, alp, list); SLOCK_LIST_UNLOCK(); SLOCK_COUNT(1); out: splx(s); } int _simple_lock_held(volatile struct simplelock *alp) { #if defined(MULTIPROCESSOR) || defined(DIAGNOSTIC) cpuid_t cpu_num = cpu_number(); #endif int s, locked = 0; s = spllock(); #if defined(MULTIPROCESSOR) if (__cpu_simple_lock_try(&alp->lock_data) == 0) locked = (alp->lock_holder == cpu_num); else __cpu_simple_unlock(&alp->lock_data); #else if (alp->lock_data == __SIMPLELOCK_LOCKED) { locked = 1; KASSERT(alp->lock_holder == cpu_num); } #endif splx(s); return (locked); } int _simple_lock_try(volatile struct simplelock *alp, const char *id, int l) { cpuid_t cpu_num = cpu_number(); int s, rv = 0; s = spllock(); /* * MULTIPROCESSOR case: This is `safe' since if it's not us, we * don't take any action. */ #if defined(MULTIPROCESSOR) /* { */ if ((rv = __cpu_simple_lock_try(&alp->lock_data)) == 0) { if (alp->lock_holder == cpu_num) SLOCK_WHERE("simple_lock_try: locking against myself\n", alp, id, l); goto out; } #else if (alp->lock_data == __SIMPLELOCK_LOCKED) { SLOCK_WHERE("simple_lock_try: lock held\n", alp, id, l); goto out; } alp->lock_data = __SIMPLELOCK_LOCKED; #endif /* MULTIPROCESSOR */ /* } */ /* * At this point, we have acquired the lock. */ rv = 1; alp->lock_file = id; alp->lock_line = l; alp->lock_holder = cpu_num; SLOCK_LIST_LOCK(); TAILQ_INSERT_TAIL(&simplelock_list, alp, list); SLOCK_LIST_UNLOCK(); SLOCK_COUNT(1); out: splx(s); return (rv); } void _simple_unlock(volatile struct simplelock *alp, const char *id, int l) { int s; s = spllock(); /* * MULTIPROCESSOR case: This is `safe' because we think we hold * the lock, and if we don't, we don't take any action. */ if (alp->lock_data == __SIMPLELOCK_UNLOCKED) { SLOCK_WHERE("simple_unlock: lock not held\n", alp, id, l); goto out; } SLOCK_LIST_LOCK(); TAILQ_REMOVE(&simplelock_list, alp, list); SLOCK_LIST_UNLOCK(); SLOCK_COUNT(-1); alp->list.tqe_next = NULL; /* sanity */ alp->list.tqe_prev = NULL; /* sanity */ alp->unlock_file = id; alp->unlock_line = l; #if defined(MULTIPROCESSOR) /* { */ alp->lock_holder = LK_NOCPU; /* Now that we've modified all fields, release the lock. */ __cpu_simple_unlock(&alp->lock_data); #else alp->lock_data = __SIMPLELOCK_UNLOCKED; KASSERT(alp->lock_holder == cpu_number()); alp->lock_holder = LK_NOCPU; #endif /* } */ out: splx(s); } void simple_lock_dump(void) { volatile struct simplelock *alp; int s; s = spllock(); SLOCK_LIST_LOCK(); lock_printf("all simple locks:\n"); TAILQ_FOREACH(alp, &simplelock_list, list) { lock_printf("%p CPU %lu %s:%d\n", alp, alp->lock_holder, alp->lock_file, alp->lock_line); } SLOCK_LIST_UNLOCK(); splx(s); } void simple_lock_freecheck(void *start, void *end) { volatile struct simplelock *alp; int s; s = spllock(); SLOCK_LIST_LOCK(); TAILQ_FOREACH(alp, &simplelock_list, list) { if ((volatile void *)alp >= start && (volatile void *)alp < end) { lock_printf("freeing simple_lock %p CPU %lu %s:%d\n", alp, alp->lock_holder, alp->lock_file, alp->lock_line); SLOCK_DEBUGGER(); } } SLOCK_LIST_UNLOCK(); splx(s); } /* * We must be holding exactly one lock: the sched_lock. */ void simple_lock_switchcheck(void) { simple_lock_only_held(&sched_lock, "switching"); } void simple_lock_only_held(volatile struct simplelock *lp, const char *where) { volatile struct simplelock *alp; cpuid_t cpu_num = cpu_number(); int s; if (lp) { LOCK_ASSERT(simple_lock_held(lp)); } s = spllock(); SLOCK_LIST_LOCK(); TAILQ_FOREACH(alp, &simplelock_list, list) { if (alp == lp) continue; #if defined(MULTIPROCESSOR) if (alp == &kernel_lock) continue; #endif /* defined(MULTIPROCESSOR) */ if (alp->lock_holder == cpu_num) break; } SLOCK_LIST_UNLOCK(); splx(s); if (alp != NULL) { lock_printf("\n%s with held simple_lock %p " "CPU %lu %s:%d\n", where, alp, alp->lock_holder, alp->lock_file, alp->lock_line); SLOCK_TRACE(); SLOCK_DEBUGGER(); } } #endif /* LOCKDEBUG */ /* } */ #if defined(MULTIPROCESSOR) /* * Functions for manipulating the kernel_lock. We put them here * so that they show up in profiles. */ /* * splbiglock: block IPLs which need to grab kernel_lock. * XXX splvm or splaudio should be enough. */ #if !defined(__HAVE_SPLBIGLOCK) #define splbiglock() splclock() #endif void _kernel_lock_init(void) { simple_lock_init(&kernel_lock); } /* * Acquire/release the kernel lock. Intended for use in the scheduler * and the lower half of the kernel. */ void _kernel_lock(int flag) { struct cpu_info *ci = curcpu(); SCHED_ASSERT_UNLOCKED(); if (ci->ci_data.cpu_biglock_count > 0) { LOCK_ASSERT(simple_lock_held(&kernel_lock)); ci->ci_data.cpu_biglock_count++; } else { int s; s = splbiglock(); while (!simple_lock_try(&kernel_lock)) { splx(s); SPINLOCK_SPIN_HOOK; s = splbiglock(); } ci->ci_data.cpu_biglock_count++; splx(s); } } void _kernel_unlock(void) { struct cpu_info *ci = curcpu(); int s; KASSERT(ci->ci_data.cpu_biglock_count > 0); s = splbiglock(); if ((--ci->ci_data.cpu_biglock_count) == 0) simple_unlock(&kernel_lock); splx(s); } /* * Acquire/release the kernel_lock on behalf of a process. Intended for * use in the top half of the kernel. */ void _kernel_proc_lock(struct lwp *l) { SCHED_ASSERT_UNLOCKED(); _kernel_lock(0); } void _kernel_proc_unlock(struct lwp *l) { _kernel_unlock(); } int _kernel_lock_release_all() { struct cpu_info *ci = curcpu(); int hold_count; hold_count = ci->ci_data.cpu_biglock_count; if (hold_count) { int s; s = splbiglock(); ci->ci_data.cpu_biglock_count = 0; simple_unlock(&kernel_lock); splx(s); } return hold_count; } void _kernel_lock_acquire_count(int hold_count) { KASSERT(curcpu()->ci_data.cpu_biglock_count == 0); if (hold_count != 0) { struct cpu_info *ci = curcpu(); int s; s = splbiglock(); while (!simple_lock_try(&kernel_lock)) { splx(s); SPINLOCK_SPIN_HOOK; s = splbiglock(); } ci->ci_data.cpu_biglock_count = hold_count; splx(s); } } #if defined(DEBUG) void _kernel_lock_assert_locked() { LOCK_ASSERT(simple_lock_held(&kernel_lock)); } #endif #endif /* MULTIPROCESSOR */