/* $NetBSD: kern_lock.c,v 1.110.2.17 2007/10/18 15:47:33 ad Exp $ */ /*- * Copyright (c) 1999, 2000, 2006, 2007 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, and by Andrew Doran. * * 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 1.110.2.17 2007/10/18 15:47:33 ad Exp $"); #include "opt_multiprocessor.h" #include #include #include #include #include #include #include #include #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 */ void lock_printf(const char *fmt, ...) __attribute__((__format__(__printf__,1,2))); static int acquire(struct lock **, int *, int, int, int, uintptr_t); int lock_debug_syslog = 0; /* defaults to printf, but can be patched */ int kernel_lock_id; __cpu_simple_lock_t kernel_lock; #if defined(LOCKDEBUG) || defined(DIAGNOSTIC) /* { */ #define COUNT(lkp, l, cpu_id, x) (l)->l_locks += (x) #else #define COUNT(lkp, p, cpu_id, x) #endif /* LOCKDEBUG || DIAGNOSTIC */ /* } */ #define RETURN_ADDRESS ((uintptr_t)__builtin_return_address(0)) /* * Acquire a resource. */ static int acquire(struct lock **lkpp, int *s, int extflags, int drain, int wanted, uintptr_t ra) { int error; struct lock *lkp = *lkpp; LOCKSTAT_TIMER(slptime); LOCKSTAT_FLAG(lsflag); KASSERT(drain || (wanted & LK_WAIT_NONZERO) == 0); LOCKSTAT_ENTER(lsflag); 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; } LOCKSTAT_START_TIMER(lsflag, slptime); error = mtsleep(drain ? (void *)&lkp->lk_flags : (void *)lkp, lkp->lk_prio, lkp->lk_wmesg, lkp->lk_timo, __UNVOLATILE(&lkp->lk_interlock)); LOCKSTAT_STOP_TIMER(lsflag, slptime); LOCKSTAT_EVENT_RA(lsflag, (void *)(uintptr_t)lkp, LB_LOCKMGR | LB_SLEEP1, 1, slptime, ra); 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; } } LOCKSTAT_EXIT(lsflag); return error; } #define SETHOLDER(lkp, pid, lid, cpu_id) \ do { \ (lkp)->lk_lockholder = pid; \ (lkp)->lk_locklwp = lid; \ } while (/*CONSTCOND*/0) #define WEHOLDIT(lkp, pid, lid, cpu_id) \ ((lkp)->lk_lockholder == (pid) && (lkp)->lk_locklwp == (lid)) #define WAKEUP_WAITER(lkp) \ do { \ if (((lkp)->lk_flags & LK_WAIT_NONZERO) != 0) { \ wakeup((lkp)); \ } \ } while (/*CONSTCOND*/0) #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 */ static void lockpanic(struct lock *lkp, const char *fmt, ...) { char s[150], b[150]; static const char *locktype[] = { "*0*", "shared", "exclusive", "upgrade", "exclupgrade", "downgrade", "release", "drain", "exclother", "*9*", "*10*", "*11*", "*12*", "*13*", "*14*", "*15*" }; va_list ap; va_start(ap, fmt); vsnprintf(s, sizeof(s), fmt, ap); va_end(ap); bitmask_snprintf(lkp->lk_flags, __LK_FLAG_BITS, b, sizeof(b)); panic("%s (" "type %s flags %s, sharecount %d, exclusivecount %d, " "recurselevel %d, waitcount %d, wmesg %s" ", lock_addr %p, unlock_addr %p" ")\n", s, locktype[lkp->lk_flags & LK_TYPE_MASK], b, lkp->lk_sharecount, lkp->lk_exclusivecount, lkp->lk_recurselevel, lkp->lk_waitcount, lkp->lk_wmesg, (void *)lkp->lk_lock_addr, (void *)lkp->lk_unlock_addr ); } /* * Initialize a lock; required before use. */ void lockinit(struct lock *lkp, pri_t prio, const char *wmesg, int timo, int flags) { memset(lkp, 0, sizeof(struct lock)); lkp->lk_flags = flags & LK_EXTFLG_MASK; mutex_init(&lkp->lk_interlock, MUTEX_DEFAULT, IPL_NONE); lkp->lk_lockholder = LK_NOPROC; lkp->lk_prio = prio; lkp->lk_timo = timo; lkp->lk_wmesg = wmesg; lkp->lk_lock_addr = 0; lkp->lk_unlock_addr = 0; } void lockdestroy(struct lock *lkp) { mutex_destroy(&lkp->lk_interlock); } /* * Determine the status of a lock. */ int lockstatus(struct lock *lkp) { int lock_type = 0; struct lwp *l = curlwp; /* XXX */ pid_t pid; lwpid_t lid; cpuid_t cpu_num; if (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; } mutex_enter(&lkp->lk_interlock); 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; else if (lkp->lk_flags & (LK_WANT_EXCL | LK_WANT_UPGRADE)) lock_type = LK_EXCLOTHER; mutex_exit(&lkp->lk_interlock); return (lock_type); } /* * 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 lockmgr(struct lock *lkp, u_int flags, kmutex_t *interlkp) { 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); KASSERT((l->l_pflag & LP_INTR) == 0 || panicstr != NULL); mutex_enter(&lkp->lk_interlock); if (flags & LK_INTERLOCK) mutex_exit(interlkp); extflags = (flags | lkp->lk_flags) & LK_EXTFLG_MASK; 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) lockpanic(lkp, "lockmgr: using decommissioned lock"); if ((flags & LK_TYPE_MASK) != LK_RELEASE || WEHOLDIT(lkp, pid, lid, cpu_num) == 0) lockpanic(lkp, "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, RETURN_ADDRESS); 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) lockpanic(lkp, "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_addr = RETURN_ADDRESS; #endif 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) lockpanic(lkp, "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, RETURN_ADDRESS); 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_addr = RETURN_ADDRESS; #endif if (lkp->lk_exclusivecount != 0) lockpanic(lkp, "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 lockpanic(lkp, "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, RETURN_ADDRESS); 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, RETURN_ADDRESS); 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_addr = RETURN_ADDRESS; #endif if (lkp->lk_exclusivecount != 0) lockpanic(lkp, "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) { lockpanic(lkp, "lockmgr: pid %d.%d, not " "exclusive lock holder %d.%d " "unlocking", pid, lid, lkp->lk_lockholder, lkp->lk_locklwp); } 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_addr = RETURN_ADDRESS; #endif } } 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 lockpanic(lkp, "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)) lockpanic(lkp, "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, RETURN_ADDRESS); if (error) break; lkp->lk_flags |= LK_HAVE_EXCL; if ((extflags & LK_RESURRECT) == 0) lkp->lk_flags |= LK_DRAINING; SETHOLDER(lkp, pid, lid, cpu_num); #if defined(LOCKDEBUG) lkp->lk_lock_addr = RETURN_ADDRESS; #endif 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: mutex_exit(&lkp->lk_interlock); lockpanic(lkp, "lockmgr: unknown locktype request %d", flags & LK_TYPE_MASK); /* NOTREACHED */ } if ((lkp->lk_flags & LK_WAITDRAIN) != 0 && ((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) lockpanic(lkp, "lockmgr: deadlock (see previous panic)"); mutex_exit(&lkp->lk_interlock); return (error); } /* * Print out information about state of a lock. Used by VOP_PRINT * routines to display ststus about contained locks. */ void lockmgr_printinfo(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); printf("pid %d.%d", lkp->lk_lockholder, lkp->lk_locklwp); } else printf(" not locked"); if (lkp->lk_waitcount > 0) printf(" with %d pending", lkp->lk_waitcount); } #if defined(LOCKDEBUG) void assert_sleepable(struct simplelock *interlock, const char *msg) { if (panicstr != NULL) return; LOCKDEBUG_BARRIER(&kernel_lock, 1); if (CURCPU_IDLE_P()) { panic("assert_sleepable: idle"); } } #endif /* * Functions for manipulating the kernel_lock. We put them here * so that they show up in profiles. */ #define _KERNEL_LOCK_ABORT(msg) \ LOCKDEBUG_ABORT(kernel_lock_id, &kernel_lock, &_kernel_lock_ops, \ __func__, msg) #ifdef LOCKDEBUG #define _KERNEL_LOCK_ASSERT(cond) \ do { \ if (!(cond)) \ _KERNEL_LOCK_ABORT("assertion failed: " #cond); \ } while (/* CONSTCOND */ 0) #else #define _KERNEL_LOCK_ASSERT(cond) /* nothing */ #endif void _kernel_lock_dump(volatile void *); lockops_t _kernel_lock_ops = { "Kernel lock", 0, _kernel_lock_dump }; /* * Initialize the kernel lock. */ void kernel_lock_init(void) { __cpu_simple_lock_init(&kernel_lock); kernel_lock_id = LOCKDEBUG_ALLOC(&kernel_lock, &_kernel_lock_ops, RETURN_ADDRESS); } /* * Print debugging information about the kernel lock. */ void _kernel_lock_dump(volatile void *junk) { struct cpu_info *ci = curcpu(); (void)junk; printf_nolog("curcpu holds : %18d wanted by: %#018lx\n", ci->ci_biglock_count, (long)ci->ci_biglock_wanted); } /* * Acquire 'nlocks' holds on the kernel lock. If 'l' is non-null, the * acquisition is from process context. */ void _kernel_lock(int nlocks, struct lwp *l) { struct cpu_info *ci = curcpu(); LOCKSTAT_TIMER(spintime); LOCKSTAT_FLAG(lsflag); struct lwp *owant; #ifdef LOCKDEBUG u_int spins; #endif int s; if (nlocks == 0) return; _KERNEL_LOCK_ASSERT(nlocks > 0); l = curlwp; if (ci->ci_biglock_count != 0) { _KERNEL_LOCK_ASSERT(__SIMPLELOCK_LOCKED_P(&kernel_lock)); ci->ci_biglock_count += nlocks; l->l_blcnt += nlocks; return; } _KERNEL_LOCK_ASSERT(l->l_blcnt == 0); LOCKDEBUG_WANTLOCK(kernel_lock_id, RETURN_ADDRESS, 0); s = splvm(); if (__cpu_simple_lock_try(&kernel_lock)) { ci->ci_biglock_count = nlocks; l->l_blcnt = nlocks; LOCKDEBUG_LOCKED(kernel_lock_id, RETURN_ADDRESS, 0); splx(s); return; } LOCKSTAT_ENTER(lsflag); LOCKSTAT_START_TIMER(lsflag, spintime); /* * Before setting ci_biglock_wanted we must post a store * fence (see kern_mutex.c). This is accomplished by the * __cpu_simple_lock_try() above. */ owant = ci->ci_biglock_wanted; ci->ci_biglock_wanted = curlwp; /* XXXAD */ #ifdef LOCKDEBUG spins = 0; #endif do { splx(s); while (kernel_lock == __SIMPLELOCK_LOCKED) { #ifdef LOCKDEBUG if (SPINLOCK_SPINOUT(spins)) _KERNEL_LOCK_ABORT("spinout"); #endif SPINLOCK_BACKOFF_HOOK; SPINLOCK_SPIN_HOOK; } (void)splvm(); } while (!__cpu_simple_lock_try(&kernel_lock)); ci->ci_biglock_wanted = owant; ci->ci_biglock_count = nlocks; l->l_blcnt = nlocks; LOCKSTAT_STOP_TIMER(lsflag, spintime); LOCKDEBUG_LOCKED(kernel_lock_id, RETURN_ADDRESS, 0); splx(s); /* * Again, another store fence is required (see kern_mutex.c). */ mb_write(); if (owant == NULL) { LOCKSTAT_EVENT(lsflag, &kernel_lock, LB_KERNEL_LOCK | LB_SPIN, 1, spintime); } LOCKSTAT_EXIT(lsflag); } /* * Release 'nlocks' holds on the kernel lock. If 'nlocks' is zero, release * all holds. If 'l' is non-null, the release is from process context. */ void _kernel_unlock(int nlocks, struct lwp *l, int *countp) { struct cpu_info *ci = curcpu(); u_int olocks; int s; l = curlwp; _KERNEL_LOCK_ASSERT(nlocks < 2); olocks = l->l_blcnt; if (olocks == 0) { _KERNEL_LOCK_ASSERT(nlocks <= 0); if (countp != NULL) *countp = 0; return; } _KERNEL_LOCK_ASSERT(__SIMPLELOCK_LOCKED_P(&kernel_lock)); if (nlocks == 0) nlocks = olocks; else if (nlocks == -1) { nlocks = 1; _KERNEL_LOCK_ASSERT(olocks == 1); } _KERNEL_LOCK_ASSERT(ci->ci_biglock_count >= l->l_blcnt); l->l_blcnt -= nlocks; if (ci->ci_biglock_count == nlocks) { s = splvm(); LOCKDEBUG_UNLOCKED(kernel_lock_id, RETURN_ADDRESS, 0); ci->ci_biglock_count = 0; __cpu_simple_unlock(&kernel_lock); splx(s); } else ci->ci_biglock_count -= nlocks; if (countp != NULL) *countp = olocks; } #if defined(DEBUG) /* * Assert that the kernel lock is held. */ void _kernel_lock_assert_locked(void) { if (!__SIMPLELOCK_LOCKED_P(&kernel_lock) || curcpu()->ci_biglock_count == 0) _KERNEL_LOCK_ABORT("not locked"); } void _kernel_lock_assert_unlocked() { if (curcpu()->ci_biglock_count != 0) _KERNEL_LOCK_ABORT("locked"); } #endif