/src/freebsd/sys/kern/kern_lock.c
C | 1462 lines | 1037 code | 139 blank | 286 comment | 281 complexity | 1e6cefe4cdb53a94906ce02cb7469c73 MD5 | raw file
Possible License(s): CC0-1.0, MIT, LGPL-2.0, LGPL-3.0, WTFPL, GPL-2.0, BSD-2-Clause, AGPL-3.0, CC-BY-SA-3.0, MPL-2.0, JSON, BSD-3-Clause-No-Nuclear-License-2014, LGPL-2.1, CPL-1.0, AGPL-1.0, 0BSD, ISC, Apache-2.0, GPL-3.0, IPL-1.0, MPL-2.0-no-copyleft-exception, BSD-3-Clause
- /*-
- * Copyright (c) 2008 Attilio Rao <attilio@FreeBSD.org>
- * All rights reserved.
- *
- * 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(s), this list of conditions and the following disclaimer as
- * the first lines of this file unmodified other than the possible
- * addition of one or more copyright notices.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice(s), this list of conditions and the following disclaimer in the
- * documentation and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``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 COPYRIGHT HOLDER(S) 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.
- */
- #include "opt_adaptive_lockmgrs.h"
- #include "opt_ddb.h"
- #include "opt_kdtrace.h"
- #include <sys/cdefs.h>
- __FBSDID("$FreeBSD$");
- #include <sys/param.h>
- #include <sys/ktr.h>
- #include <sys/lock.h>
- #include <sys/lock_profile.h>
- #include <sys/lockmgr.h>
- #include <sys/mutex.h>
- #include <sys/proc.h>
- #include <sys/sleepqueue.h>
- #ifdef DEBUG_LOCKS
- #include <sys/stack.h>
- #endif
- #include <sys/sysctl.h>
- #include <sys/systm.h>
- #include <machine/cpu.h>
- #ifdef DDB
- #include <ddb/ddb.h>
- #endif
- CTASSERT(((LK_ADAPTIVE | LK_NOSHARE) & LO_CLASSFLAGS) ==
- (LK_ADAPTIVE | LK_NOSHARE));
- CTASSERT(LK_UNLOCKED == (LK_UNLOCKED &
- ~(LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS)));
- #define SQ_EXCLUSIVE_QUEUE 0
- #define SQ_SHARED_QUEUE 1
- #ifndef INVARIANTS
- #define _lockmgr_assert(lk, what, file, line)
- #define TD_LOCKS_INC(td)
- #define TD_LOCKS_DEC(td)
- #else
- #define TD_LOCKS_INC(td) ((td)->td_locks++)
- #define TD_LOCKS_DEC(td) ((td)->td_locks--)
- #endif
- #define TD_SLOCKS_INC(td) ((td)->td_lk_slocks++)
- #define TD_SLOCKS_DEC(td) ((td)->td_lk_slocks--)
- #ifndef DEBUG_LOCKS
- #define STACK_PRINT(lk)
- #define STACK_SAVE(lk)
- #define STACK_ZERO(lk)
- #else
- #define STACK_PRINT(lk) stack_print_ddb(&(lk)->lk_stack)
- #define STACK_SAVE(lk) stack_save(&(lk)->lk_stack)
- #define STACK_ZERO(lk) stack_zero(&(lk)->lk_stack)
- #endif
- #define LOCK_LOG2(lk, string, arg1, arg2) \
- if (LOCK_LOG_TEST(&(lk)->lock_object, 0)) \
- CTR2(KTR_LOCK, (string), (arg1), (arg2))
- #define LOCK_LOG3(lk, string, arg1, arg2, arg3) \
- if (LOCK_LOG_TEST(&(lk)->lock_object, 0)) \
- CTR3(KTR_LOCK, (string), (arg1), (arg2), (arg3))
- #define GIANT_DECLARE \
- int _i = 0; \
- WITNESS_SAVE_DECL(Giant)
- #define GIANT_RESTORE() do { \
- if (_i > 0) { \
- while (_i--) \
- mtx_lock(&Giant); \
- WITNESS_RESTORE(&Giant.lock_object, Giant); \
- } \
- } while (0)
- #define GIANT_SAVE() do { \
- if (mtx_owned(&Giant)) { \
- WITNESS_SAVE(&Giant.lock_object, Giant); \
- while (mtx_owned(&Giant)) { \
- _i++; \
- mtx_unlock(&Giant); \
- } \
- } \
- } while (0)
- #define LK_CAN_SHARE(x) \
- (((x) & LK_SHARE) && (((x) & LK_EXCLUSIVE_WAITERS) == 0 || \
- ((x) & LK_EXCLUSIVE_SPINNERS) == 0 || \
- curthread->td_lk_slocks || (curthread->td_pflags & TDP_DEADLKTREAT)))
- #define LK_TRYOP(x) \
- ((x) & LK_NOWAIT)
- #define LK_CAN_WITNESS(x) \
- (((x) & LK_NOWITNESS) == 0 && !LK_TRYOP(x))
- #define LK_TRYWIT(x) \
- (LK_TRYOP(x) ? LOP_TRYLOCK : 0)
- #define LK_CAN_ADAPT(lk, f) \
- (((lk)->lock_object.lo_flags & LK_ADAPTIVE) != 0 && \
- ((f) & LK_SLEEPFAIL) == 0)
- #define lockmgr_disowned(lk) \
- (((lk)->lk_lock & ~(LK_FLAGMASK & ~LK_SHARE)) == LK_KERNPROC)
- #define lockmgr_xlocked(lk) \
- (((lk)->lk_lock & ~(LK_FLAGMASK & ~LK_SHARE)) == (uintptr_t)curthread)
- static void assert_lockmgr(const struct lock_object *lock, int how);
- #ifdef DDB
- static void db_show_lockmgr(const struct lock_object *lock);
- #endif
- static void lock_lockmgr(struct lock_object *lock, int how);
- #ifdef KDTRACE_HOOKS
- static int owner_lockmgr(const struct lock_object *lock,
- struct thread **owner);
- #endif
- static int unlock_lockmgr(struct lock_object *lock);
- struct lock_class lock_class_lockmgr = {
- .lc_name = "lockmgr",
- .lc_flags = LC_RECURSABLE | LC_SLEEPABLE | LC_SLEEPLOCK | LC_UPGRADABLE,
- .lc_assert = assert_lockmgr,
- #ifdef DDB
- .lc_ddb_show = db_show_lockmgr,
- #endif
- .lc_lock = lock_lockmgr,
- .lc_unlock = unlock_lockmgr,
- #ifdef KDTRACE_HOOKS
- .lc_owner = owner_lockmgr,
- #endif
- };
- #ifdef ADAPTIVE_LOCKMGRS
- static u_int alk_retries = 10;
- static u_int alk_loops = 10000;
- static SYSCTL_NODE(_debug, OID_AUTO, lockmgr, CTLFLAG_RD, NULL,
- "lockmgr debugging");
- SYSCTL_UINT(_debug_lockmgr, OID_AUTO, retries, CTLFLAG_RW, &alk_retries, 0, "");
- SYSCTL_UINT(_debug_lockmgr, OID_AUTO, loops, CTLFLAG_RW, &alk_loops, 0, "");
- #endif
- static __inline struct thread *
- lockmgr_xholder(const struct lock *lk)
- {
- uintptr_t x;
- x = lk->lk_lock;
- return ((x & LK_SHARE) ? NULL : (struct thread *)LK_HOLDER(x));
- }
- /*
- * It assumes sleepq_lock held and returns with this one unheld.
- * It also assumes the generic interlock is sane and previously checked.
- * If LK_INTERLOCK is specified the interlock is not reacquired after the
- * sleep.
- */
- static __inline int
- sleeplk(struct lock *lk, u_int flags, struct lock_object *ilk,
- const char *wmesg, int pri, int timo, int queue)
- {
- GIANT_DECLARE;
- struct lock_class *class;
- int catch, error;
- class = (flags & LK_INTERLOCK) ? LOCK_CLASS(ilk) : NULL;
- catch = pri & PCATCH;
- pri &= PRIMASK;
- error = 0;
- LOCK_LOG3(lk, "%s: %p blocking on the %s sleepqueue", __func__, lk,
- (queue == SQ_EXCLUSIVE_QUEUE) ? "exclusive" : "shared");
- if (flags & LK_INTERLOCK)
- class->lc_unlock(ilk);
- if (queue == SQ_EXCLUSIVE_QUEUE && (flags & LK_SLEEPFAIL) != 0)
- lk->lk_exslpfail++;
- GIANT_SAVE();
- sleepq_add(&lk->lock_object, NULL, wmesg, SLEEPQ_LK | (catch ?
- SLEEPQ_INTERRUPTIBLE : 0), queue);
- if ((flags & LK_TIMELOCK) && timo)
- sleepq_set_timeout(&lk->lock_object, timo);
- /*
- * Decisional switch for real sleeping.
- */
- if ((flags & LK_TIMELOCK) && timo && catch)
- error = sleepq_timedwait_sig(&lk->lock_object, pri);
- else if ((flags & LK_TIMELOCK) && timo)
- error = sleepq_timedwait(&lk->lock_object, pri);
- else if (catch)
- error = sleepq_wait_sig(&lk->lock_object, pri);
- else
- sleepq_wait(&lk->lock_object, pri);
- GIANT_RESTORE();
- if ((flags & LK_SLEEPFAIL) && error == 0)
- error = ENOLCK;
- return (error);
- }
- static __inline int
- wakeupshlk(struct lock *lk, const char *file, int line)
- {
- uintptr_t v, x;
- u_int realexslp;
- int queue, wakeup_swapper;
- TD_LOCKS_DEC(curthread);
- TD_SLOCKS_DEC(curthread);
- WITNESS_UNLOCK(&lk->lock_object, 0, file, line);
- LOCK_LOG_LOCK("SUNLOCK", &lk->lock_object, 0, 0, file, line);
- wakeup_swapper = 0;
- for (;;) {
- x = lk->lk_lock;
- /*
- * If there is more than one shared lock held, just drop one
- * and return.
- */
- if (LK_SHARERS(x) > 1) {
- if (atomic_cmpset_rel_ptr(&lk->lk_lock, x,
- x - LK_ONE_SHARER))
- break;
- continue;
- }
- /*
- * If there are not waiters on the exclusive queue, drop the
- * lock quickly.
- */
- if ((x & LK_ALL_WAITERS) == 0) {
- MPASS((x & ~LK_EXCLUSIVE_SPINNERS) ==
- LK_SHARERS_LOCK(1));
- if (atomic_cmpset_rel_ptr(&lk->lk_lock, x, LK_UNLOCKED))
- break;
- continue;
- }
- /*
- * We should have a sharer with waiters, so enter the hard
- * path in order to handle wakeups correctly.
- */
- sleepq_lock(&lk->lock_object);
- x = lk->lk_lock & (LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS);
- v = LK_UNLOCKED;
- /*
- * If the lock has exclusive waiters, give them preference in
- * order to avoid deadlock with shared runners up.
- * If interruptible sleeps left the exclusive queue empty
- * avoid a starvation for the threads sleeping on the shared
- * queue by giving them precedence and cleaning up the
- * exclusive waiters bit anyway.
- * Please note that lk_exslpfail count may be lying about
- * the real number of waiters with the LK_SLEEPFAIL flag on
- * because they may be used in conjuction with interruptible
- * sleeps so lk_exslpfail might be considered an 'upper limit'
- * bound, including the edge cases.
- */
- realexslp = sleepq_sleepcnt(&lk->lock_object,
- SQ_EXCLUSIVE_QUEUE);
- if ((x & LK_EXCLUSIVE_WAITERS) != 0 && realexslp != 0) {
- if (lk->lk_exslpfail < realexslp) {
- lk->lk_exslpfail = 0;
- queue = SQ_EXCLUSIVE_QUEUE;
- v |= (x & LK_SHARED_WAITERS);
- } else {
- lk->lk_exslpfail = 0;
- LOCK_LOG2(lk,
- "%s: %p has only LK_SLEEPFAIL sleepers",
- __func__, lk);
- LOCK_LOG2(lk,
- "%s: %p waking up threads on the exclusive queue",
- __func__, lk);
- wakeup_swapper =
- sleepq_broadcast(&lk->lock_object,
- SLEEPQ_LK, 0, SQ_EXCLUSIVE_QUEUE);
- queue = SQ_SHARED_QUEUE;
- }
-
- } else {
- /*
- * Exclusive waiters sleeping with LK_SLEEPFAIL on
- * and using interruptible sleeps/timeout may have
- * left spourious lk_exslpfail counts on, so clean
- * it up anyway.
- */
- lk->lk_exslpfail = 0;
- queue = SQ_SHARED_QUEUE;
- }
- if (!atomic_cmpset_rel_ptr(&lk->lk_lock, LK_SHARERS_LOCK(1) | x,
- v)) {
- sleepq_release(&lk->lock_object);
- continue;
- }
- LOCK_LOG3(lk, "%s: %p waking up threads on the %s queue",
- __func__, lk, queue == SQ_SHARED_QUEUE ? "shared" :
- "exclusive");
- wakeup_swapper |= sleepq_broadcast(&lk->lock_object, SLEEPQ_LK,
- 0, queue);
- sleepq_release(&lk->lock_object);
- break;
- }
- lock_profile_release_lock(&lk->lock_object);
- return (wakeup_swapper);
- }
- static void
- assert_lockmgr(const struct lock_object *lock, int what)
- {
- panic("lockmgr locks do not support assertions");
- }
- static void
- lock_lockmgr(struct lock_object *lock, int how)
- {
- panic("lockmgr locks do not support sleep interlocking");
- }
- static int
- unlock_lockmgr(struct lock_object *lock)
- {
- panic("lockmgr locks do not support sleep interlocking");
- }
- #ifdef KDTRACE_HOOKS
- static int
- owner_lockmgr(const struct lock_object *lock, struct thread **owner)
- {
- panic("lockmgr locks do not support owner inquiring");
- }
- #endif
- void
- lockinit(struct lock *lk, int pri, const char *wmesg, int timo, int flags)
- {
- int iflags;
- MPASS((flags & ~LK_INIT_MASK) == 0);
- ASSERT_ATOMIC_LOAD_PTR(lk->lk_lock,
- ("%s: lockmgr not aligned for %s: %p", __func__, wmesg,
- &lk->lk_lock));
- iflags = LO_SLEEPABLE | LO_UPGRADABLE;
- if (flags & LK_CANRECURSE)
- iflags |= LO_RECURSABLE;
- if ((flags & LK_NODUP) == 0)
- iflags |= LO_DUPOK;
- if (flags & LK_NOPROFILE)
- iflags |= LO_NOPROFILE;
- if ((flags & LK_NOWITNESS) == 0)
- iflags |= LO_WITNESS;
- if (flags & LK_QUIET)
- iflags |= LO_QUIET;
- iflags |= flags & (LK_ADAPTIVE | LK_NOSHARE);
- lk->lk_lock = LK_UNLOCKED;
- lk->lk_recurse = 0;
- lk->lk_exslpfail = 0;
- lk->lk_timo = timo;
- lk->lk_pri = pri;
- lock_init(&lk->lock_object, &lock_class_lockmgr, wmesg, NULL, iflags);
- STACK_ZERO(lk);
- }
- /*
- * XXX: Gross hacks to manipulate external lock flags after
- * initialization. Used for certain vnode and buf locks.
- */
- void
- lockallowshare(struct lock *lk)
- {
- lockmgr_assert(lk, KA_XLOCKED);
- lk->lock_object.lo_flags &= ~LK_NOSHARE;
- }
- void
- lockallowrecurse(struct lock *lk)
- {
- lockmgr_assert(lk, KA_XLOCKED);
- lk->lock_object.lo_flags |= LO_RECURSABLE;
- }
- void
- lockdisablerecurse(struct lock *lk)
- {
- lockmgr_assert(lk, KA_XLOCKED);
- lk->lock_object.lo_flags &= ~LO_RECURSABLE;
- }
- void
- lockdestroy(struct lock *lk)
- {
- KASSERT(lk->lk_lock == LK_UNLOCKED, ("lockmgr still held"));
- KASSERT(lk->lk_recurse == 0, ("lockmgr still recursed"));
- KASSERT(lk->lk_exslpfail == 0, ("lockmgr still exclusive waiters"));
- lock_destroy(&lk->lock_object);
- }
- int
- __lockmgr_args(struct lock *lk, u_int flags, struct lock_object *ilk,
- const char *wmesg, int pri, int timo, const char *file, int line)
- {
- GIANT_DECLARE;
- struct lock_class *class;
- const char *iwmesg;
- uintptr_t tid, v, x;
- u_int op, realexslp;
- int error, ipri, itimo, queue, wakeup_swapper;
- #ifdef LOCK_PROFILING
- uint64_t waittime = 0;
- int contested = 0;
- #endif
- #ifdef ADAPTIVE_LOCKMGRS
- volatile struct thread *owner;
- u_int i, spintries = 0;
- #endif
- error = 0;
- tid = (uintptr_t)curthread;
- op = (flags & LK_TYPE_MASK);
- iwmesg = (wmesg == LK_WMESG_DEFAULT) ? lk->lock_object.lo_name : wmesg;
- ipri = (pri == LK_PRIO_DEFAULT) ? lk->lk_pri : pri;
- itimo = (timo == LK_TIMO_DEFAULT) ? lk->lk_timo : timo;
- MPASS((flags & ~LK_TOTAL_MASK) == 0);
- KASSERT((op & (op - 1)) == 0,
- ("%s: Invalid requested operation @ %s:%d", __func__, file, line));
- KASSERT((flags & (LK_NOWAIT | LK_SLEEPFAIL)) == 0 ||
- (op != LK_DOWNGRADE && op != LK_RELEASE),
- ("%s: Invalid flags in regard of the operation desired @ %s:%d",
- __func__, file, line));
- KASSERT((flags & LK_INTERLOCK) == 0 || ilk != NULL,
- ("%s: LK_INTERLOCK passed without valid interlock @ %s:%d",
- __func__, file, line));
- class = (flags & LK_INTERLOCK) ? LOCK_CLASS(ilk) : NULL;
- if (panicstr != NULL) {
- if (flags & LK_INTERLOCK)
- class->lc_unlock(ilk);
- return (0);
- }
- if (lk->lock_object.lo_flags & LK_NOSHARE) {
- switch (op) {
- case LK_SHARED:
- op = LK_EXCLUSIVE;
- break;
- case LK_UPGRADE:
- case LK_DOWNGRADE:
- _lockmgr_assert(lk, KA_XLOCKED | KA_NOTRECURSED,
- file, line);
- return (0);
- }
- }
- wakeup_swapper = 0;
- switch (op) {
- case LK_SHARED:
- if (LK_CAN_WITNESS(flags))
- WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER,
- file, line, ilk);
- for (;;) {
- x = lk->lk_lock;
- /*
- * If no other thread has an exclusive lock, or
- * no exclusive waiter is present, bump the count of
- * sharers. Since we have to preserve the state of
- * waiters, if we fail to acquire the shared lock
- * loop back and retry.
- */
- if (LK_CAN_SHARE(x)) {
- if (atomic_cmpset_acq_ptr(&lk->lk_lock, x,
- x + LK_ONE_SHARER))
- break;
- continue;
- }
- lock_profile_obtain_lock_failed(&lk->lock_object,
- &contested, &waittime);
- /*
- * If the lock is already held by curthread in
- * exclusive way avoid a deadlock.
- */
- if (LK_HOLDER(x) == tid) {
- LOCK_LOG2(lk,
- "%s: %p already held in exclusive mode",
- __func__, lk);
- error = EDEADLK;
- break;
- }
- /*
- * If the lock is expected to not sleep just give up
- * and return.
- */
- if (LK_TRYOP(flags)) {
- LOCK_LOG2(lk, "%s: %p fails the try operation",
- __func__, lk);
- error = EBUSY;
- break;
- }
- #ifdef ADAPTIVE_LOCKMGRS
- /*
- * If the owner is running on another CPU, spin until
- * the owner stops running or the state of the lock
- * changes. We need a double-state handle here
- * because for a failed acquisition the lock can be
- * either held in exclusive mode or shared mode
- * (for the writer starvation avoidance technique).
- */
- if (LK_CAN_ADAPT(lk, flags) && (x & LK_SHARE) == 0 &&
- LK_HOLDER(x) != LK_KERNPROC) {
- owner = (struct thread *)LK_HOLDER(x);
- if (LOCK_LOG_TEST(&lk->lock_object, 0))
- CTR3(KTR_LOCK,
- "%s: spinning on %p held by %p",
- __func__, lk, owner);
- /*
- * If we are holding also an interlock drop it
- * in order to avoid a deadlock if the lockmgr
- * owner is adaptively spinning on the
- * interlock itself.
- */
- if (flags & LK_INTERLOCK) {
- class->lc_unlock(ilk);
- flags &= ~LK_INTERLOCK;
- }
- GIANT_SAVE();
- while (LK_HOLDER(lk->lk_lock) ==
- (uintptr_t)owner && TD_IS_RUNNING(owner))
- cpu_spinwait();
- GIANT_RESTORE();
- continue;
- } else if (LK_CAN_ADAPT(lk, flags) &&
- (x & LK_SHARE) != 0 && LK_SHARERS(x) &&
- spintries < alk_retries) {
- if (flags & LK_INTERLOCK) {
- class->lc_unlock(ilk);
- flags &= ~LK_INTERLOCK;
- }
- GIANT_SAVE();
- spintries++;
- for (i = 0; i < alk_loops; i++) {
- if (LOCK_LOG_TEST(&lk->lock_object, 0))
- CTR4(KTR_LOCK,
- "%s: shared spinning on %p with %u and %u",
- __func__, lk, spintries, i);
- x = lk->lk_lock;
- if ((x & LK_SHARE) == 0 ||
- LK_CAN_SHARE(x) != 0)
- break;
- cpu_spinwait();
- }
- GIANT_RESTORE();
- if (i != alk_loops)
- continue;
- }
- #endif
- /*
- * Acquire the sleepqueue chain lock because we
- * probabilly will need to manipulate waiters flags.
- */
- sleepq_lock(&lk->lock_object);
- x = lk->lk_lock;
- /*
- * if the lock can be acquired in shared mode, try
- * again.
- */
- if (LK_CAN_SHARE(x)) {
- sleepq_release(&lk->lock_object);
- continue;
- }
- #ifdef ADAPTIVE_LOCKMGRS
- /*
- * The current lock owner might have started executing
- * on another CPU (or the lock could have changed
- * owner) while we were waiting on the turnstile
- * chain lock. If so, drop the turnstile lock and try
- * again.
- */
- if (LK_CAN_ADAPT(lk, flags) && (x & LK_SHARE) == 0 &&
- LK_HOLDER(x) != LK_KERNPROC) {
- owner = (struct thread *)LK_HOLDER(x);
- if (TD_IS_RUNNING(owner)) {
- sleepq_release(&lk->lock_object);
- continue;
- }
- }
- #endif
- /*
- * Try to set the LK_SHARED_WAITERS flag. If we fail,
- * loop back and retry.
- */
- if ((x & LK_SHARED_WAITERS) == 0) {
- if (!atomic_cmpset_acq_ptr(&lk->lk_lock, x,
- x | LK_SHARED_WAITERS)) {
- sleepq_release(&lk->lock_object);
- continue;
- }
- LOCK_LOG2(lk, "%s: %p set shared waiters flag",
- __func__, lk);
- }
- /*
- * As far as we have been unable to acquire the
- * shared lock and the shared waiters flag is set,
- * we will sleep.
- */
- error = sleeplk(lk, flags, ilk, iwmesg, ipri, itimo,
- SQ_SHARED_QUEUE);
- flags &= ~LK_INTERLOCK;
- if (error) {
- LOCK_LOG3(lk,
- "%s: interrupted sleep for %p with %d",
- __func__, lk, error);
- break;
- }
- LOCK_LOG2(lk, "%s: %p resuming from the sleep queue",
- __func__, lk);
- }
- if (error == 0) {
- lock_profile_obtain_lock_success(&lk->lock_object,
- contested, waittime, file, line);
- LOCK_LOG_LOCK("SLOCK", &lk->lock_object, 0, 0, file,
- line);
- WITNESS_LOCK(&lk->lock_object, LK_TRYWIT(flags), file,
- line);
- TD_LOCKS_INC(curthread);
- TD_SLOCKS_INC(curthread);
- STACK_SAVE(lk);
- }
- break;
- case LK_UPGRADE:
- _lockmgr_assert(lk, KA_SLOCKED, file, line);
- v = lk->lk_lock;
- x = v & LK_ALL_WAITERS;
- v &= LK_EXCLUSIVE_SPINNERS;
- /*
- * Try to switch from one shared lock to an exclusive one.
- * We need to preserve waiters flags during the operation.
- */
- if (atomic_cmpset_ptr(&lk->lk_lock, LK_SHARERS_LOCK(1) | x | v,
- tid | x)) {
- LOCK_LOG_LOCK("XUPGRADE", &lk->lock_object, 0, 0, file,
- line);
- WITNESS_UPGRADE(&lk->lock_object, LOP_EXCLUSIVE |
- LK_TRYWIT(flags), file, line);
- TD_SLOCKS_DEC(curthread);
- break;
- }
- /*
- * We have been unable to succeed in upgrading, so just
- * give up the shared lock.
- */
- wakeup_swapper |= wakeupshlk(lk, file, line);
- /* FALLTHROUGH */
- case LK_EXCLUSIVE:
- if (LK_CAN_WITNESS(flags))
- WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER |
- LOP_EXCLUSIVE, file, line, ilk);
- /*
- * If curthread already holds the lock and this one is
- * allowed to recurse, simply recurse on it.
- */
- if (lockmgr_xlocked(lk)) {
- if ((flags & LK_CANRECURSE) == 0 &&
- (lk->lock_object.lo_flags & LO_RECURSABLE) == 0) {
- /*
- * If the lock is expected to not panic just
- * give up and return.
- */
- if (LK_TRYOP(flags)) {
- LOCK_LOG2(lk,
- "%s: %p fails the try operation",
- __func__, lk);
- error = EBUSY;
- break;
- }
- if (flags & LK_INTERLOCK)
- class->lc_unlock(ilk);
- panic("%s: recursing on non recursive lockmgr %s @ %s:%d\n",
- __func__, iwmesg, file, line);
- }
- lk->lk_recurse++;
- LOCK_LOG2(lk, "%s: %p recursing", __func__, lk);
- LOCK_LOG_LOCK("XLOCK", &lk->lock_object, 0,
- lk->lk_recurse, file, line);
- WITNESS_LOCK(&lk->lock_object, LOP_EXCLUSIVE |
- LK_TRYWIT(flags), file, line);
- TD_LOCKS_INC(curthread);
- break;
- }
- while (!atomic_cmpset_acq_ptr(&lk->lk_lock, LK_UNLOCKED,
- tid)) {
- lock_profile_obtain_lock_failed(&lk->lock_object,
- &contested, &waittime);
- /*
- * If the lock is expected to not sleep just give up
- * and return.
- */
- if (LK_TRYOP(flags)) {
- LOCK_LOG2(lk, "%s: %p fails the try operation",
- __func__, lk);
- error = EBUSY;
- break;
- }
- #ifdef ADAPTIVE_LOCKMGRS
- /*
- * If the owner is running on another CPU, spin until
- * the owner stops running or the state of the lock
- * changes.
- */
- x = lk->lk_lock;
- if (LK_CAN_ADAPT(lk, flags) && (x & LK_SHARE) == 0 &&
- LK_HOLDER(x) != LK_KERNPROC) {
- owner = (struct thread *)LK_HOLDER(x);
- if (LOCK_LOG_TEST(&lk->lock_object, 0))
- CTR3(KTR_LOCK,
- "%s: spinning on %p held by %p",
- __func__, lk, owner);
- /*
- * If we are holding also an interlock drop it
- * in order to avoid a deadlock if the lockmgr
- * owner is adaptively spinning on the
- * interlock itself.
- */
- if (flags & LK_INTERLOCK) {
- class->lc_unlock(ilk);
- flags &= ~LK_INTERLOCK;
- }
- GIANT_SAVE();
- while (LK_HOLDER(lk->lk_lock) ==
- (uintptr_t)owner && TD_IS_RUNNING(owner))
- cpu_spinwait();
- GIANT_RESTORE();
- continue;
- } else if (LK_CAN_ADAPT(lk, flags) &&
- (x & LK_SHARE) != 0 && LK_SHARERS(x) &&
- spintries < alk_retries) {
- if ((x & LK_EXCLUSIVE_SPINNERS) == 0 &&
- !atomic_cmpset_ptr(&lk->lk_lock, x,
- x | LK_EXCLUSIVE_SPINNERS))
- continue;
- if (flags & LK_INTERLOCK) {
- class->lc_unlock(ilk);
- flags &= ~LK_INTERLOCK;
- }
- GIANT_SAVE();
- spintries++;
- for (i = 0; i < alk_loops; i++) {
- if (LOCK_LOG_TEST(&lk->lock_object, 0))
- CTR4(KTR_LOCK,
- "%s: shared spinning on %p with %u and %u",
- __func__, lk, spintries, i);
- if ((lk->lk_lock &
- LK_EXCLUSIVE_SPINNERS) == 0)
- break;
- cpu_spinwait();
- }
- GIANT_RESTORE();
- if (i != alk_loops)
- continue;
- }
- #endif
- /*
- * Acquire the sleepqueue chain lock because we
- * probabilly will need to manipulate waiters flags.
- */
- sleepq_lock(&lk->lock_object);
- x = lk->lk_lock;
- /*
- * if the lock has been released while we spun on
- * the sleepqueue chain lock just try again.
- */
- if (x == LK_UNLOCKED) {
- sleepq_release(&lk->lock_object);
- continue;
- }
- #ifdef ADAPTIVE_LOCKMGRS
- /*
- * The current lock owner might have started executing
- * on another CPU (or the lock could have changed
- * owner) while we were waiting on the turnstile
- * chain lock. If so, drop the turnstile lock and try
- * again.
- */
- if (LK_CAN_ADAPT(lk, flags) && (x & LK_SHARE) == 0 &&
- LK_HOLDER(x) != LK_KERNPROC) {
- owner = (struct thread *)LK_HOLDER(x);
- if (TD_IS_RUNNING(owner)) {
- sleepq_release(&lk->lock_object);
- continue;
- }
- }
- #endif
- /*
- * The lock can be in the state where there is a
- * pending queue of waiters, but still no owner.
- * This happens when the lock is contested and an
- * owner is going to claim the lock.
- * If curthread is the one successfully acquiring it
- * claim lock ownership and return, preserving waiters
- * flags.
- */
- v = x & (LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS);
- if ((x & ~v) == LK_UNLOCKED) {
- v &= ~LK_EXCLUSIVE_SPINNERS;
- if (atomic_cmpset_acq_ptr(&lk->lk_lock, x,
- tid | v)) {
- sleepq_release(&lk->lock_object);
- LOCK_LOG2(lk,
- "%s: %p claimed by a new writer",
- __func__, lk);
- break;
- }
- sleepq_release(&lk->lock_object);
- continue;
- }
- /*
- * Try to set the LK_EXCLUSIVE_WAITERS flag. If we
- * fail, loop back and retry.
- */
- if ((x & LK_EXCLUSIVE_WAITERS) == 0) {
- if (!atomic_cmpset_ptr(&lk->lk_lock, x,
- x | LK_EXCLUSIVE_WAITERS)) {
- sleepq_release(&lk->lock_object);
- continue;
- }
- LOCK_LOG2(lk, "%s: %p set excl waiters flag",
- __func__, lk);
- }
- /*
- * As far as we have been unable to acquire the
- * exclusive lock and the exclusive waiters flag
- * is set, we will sleep.
- */
- error = sleeplk(lk, flags, ilk, iwmesg, ipri, itimo,
- SQ_EXCLUSIVE_QUEUE);
- flags &= ~LK_INTERLOCK;
- if (error) {
- LOCK_LOG3(lk,
- "%s: interrupted sleep for %p with %d",
- __func__, lk, error);
- break;
- }
- LOCK_LOG2(lk, "%s: %p resuming from the sleep queue",
- __func__, lk);
- }
- if (error == 0) {
- lock_profile_obtain_lock_success(&lk->lock_object,
- contested, waittime, file, line);
- LOCK_LOG_LOCK("XLOCK", &lk->lock_object, 0,
- lk->lk_recurse, file, line);
- WITNESS_LOCK(&lk->lock_object, LOP_EXCLUSIVE |
- LK_TRYWIT(flags), file, line);
- TD_LOCKS_INC(curthread);
- STACK_SAVE(lk);
- }
- break;
- case LK_DOWNGRADE:
- _lockmgr_assert(lk, KA_XLOCKED | KA_NOTRECURSED, file, line);
- LOCK_LOG_LOCK("XDOWNGRADE", &lk->lock_object, 0, 0, file, line);
- WITNESS_DOWNGRADE(&lk->lock_object, 0, file, line);
- TD_SLOCKS_INC(curthread);
- /*
- * In order to preserve waiters flags, just spin.
- */
- for (;;) {
- x = lk->lk_lock;
- MPASS((x & LK_EXCLUSIVE_SPINNERS) == 0);
- x &= LK_ALL_WAITERS;
- if (atomic_cmpset_rel_ptr(&lk->lk_lock, tid | x,
- LK_SHARERS_LOCK(1) | x))
- break;
- cpu_spinwait();
- }
- break;
- case LK_RELEASE:
- _lockmgr_assert(lk, KA_LOCKED, file, line);
- x = lk->lk_lock;
- if ((x & LK_SHARE) == 0) {
- /*
- * As first option, treact the lock as if it has not
- * any waiter.
- * Fix-up the tid var if the lock has been disowned.
- */
- if (LK_HOLDER(x) == LK_KERNPROC)
- tid = LK_KERNPROC;
- else {
- WITNESS_UNLOCK(&lk->lock_object, LOP_EXCLUSIVE,
- file, line);
- TD_LOCKS_DEC(curthread);
- }
- LOCK_LOG_LOCK("XUNLOCK", &lk->lock_object, 0,
- lk->lk_recurse, file, line);
- /*
- * The lock is held in exclusive mode.
- * If the lock is recursed also, then unrecurse it.
- */
- if (lockmgr_xlocked(lk) && lockmgr_recursed(lk)) {
- LOCK_LOG2(lk, "%s: %p unrecursing", __func__,
- lk);
- lk->lk_recurse--;
- break;
- }
- if (tid != LK_KERNPROC)
- lock_profile_release_lock(&lk->lock_object);
- if (atomic_cmpset_rel_ptr(&lk->lk_lock, tid,
- LK_UNLOCKED))
- break;
- sleepq_lock(&lk->lock_object);
- x = lk->lk_lock;
- v = LK_UNLOCKED;
- /*
- * If the lock has exclusive waiters, give them
- * preference in order to avoid deadlock with
- * shared runners up.
- * If interruptible sleeps left the exclusive queue
- * empty avoid a starvation for the threads sleeping
- * on the shared queue by giving them precedence
- * and cleaning up the exclusive waiters bit anyway.
- * Please note that lk_exslpfail count may be lying
- * about the real number of waiters with the
- * LK_SLEEPFAIL flag on because they may be used in
- * conjuction with interruptible sleeps so
- * lk_exslpfail might be considered an 'upper limit'
- * bound, including the edge cases.
- */
- MPASS((x & LK_EXCLUSIVE_SPINNERS) == 0);
- realexslp = sleepq_sleepcnt(&lk->lock_object,
- SQ_EXCLUSIVE_QUEUE);
- if ((x & LK_EXCLUSIVE_WAITERS) != 0 && realexslp != 0) {
- if (lk->lk_exslpfail < realexslp) {
- lk->lk_exslpfail = 0;
- queue = SQ_EXCLUSIVE_QUEUE;
- v |= (x & LK_SHARED_WAITERS);
- } else {
- lk->lk_exslpfail = 0;
- LOCK_LOG2(lk,
- "%s: %p has only LK_SLEEPFAIL sleepers",
- __func__, lk);
- LOCK_LOG2(lk,
- "%s: %p waking up threads on the exclusive queue",
- __func__, lk);
- wakeup_swapper =
- sleepq_broadcast(&lk->lock_object,
- SLEEPQ_LK, 0, SQ_EXCLUSIVE_QUEUE);
- queue = SQ_SHARED_QUEUE;
- }
- } else {
- /*
- * Exclusive waiters sleeping with LK_SLEEPFAIL
- * on and using interruptible sleeps/timeout
- * may have left spourious lk_exslpfail counts
- * on, so clean it up anyway.
- */
- lk->lk_exslpfail = 0;
- queue = SQ_SHARED_QUEUE;
- }
- LOCK_LOG3(lk,
- "%s: %p waking up threads on the %s queue",
- __func__, lk, queue == SQ_SHARED_QUEUE ? "shared" :
- "exclusive");
- atomic_store_rel_ptr(&lk->lk_lock, v);
- wakeup_swapper |= sleepq_broadcast(&lk->lock_object,
- SLEEPQ_LK, 0, queue);
- sleepq_release(&lk->lock_object);
- break;
- } else
- wakeup_swapper = wakeupshlk(lk, file, line);
- break;
- case LK_DRAIN:
- if (LK_CAN_WITNESS(flags))
- WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER |
- LOP_EXCLUSIVE, file, line, ilk);
- /*
- * Trying to drain a lock we already own will result in a
- * deadlock.
- */
- if (lockmgr_xlocked(lk)) {
- if (flags & LK_INTERLOCK)
- class->lc_unlock(ilk);
- panic("%s: draining %s with the lock held @ %s:%d\n",
- __func__, iwmesg, file, line);
- }
- while (!atomic_cmpset_acq_ptr(&lk->lk_lock, LK_UNLOCKED, tid)) {
- lock_profile_obtain_lock_failed(&lk->lock_object,
- &contested, &waittime);
- /*
- * If the lock is expected to not sleep just give up
- * and return.
- */
- if (LK_TRYOP(flags)) {
- LOCK_LOG2(lk, "%s: %p fails the try operation",
- __func__, lk);
- error = EBUSY;
- break;
- }
- /*
- * Acquire the sleepqueue chain lock because we
- * probabilly will need to manipulate waiters flags.
- */
- sleepq_lock(&lk->lock_object);
- x = lk->lk_lock;
- /*
- * if the lock has been released while we spun on
- * the sleepqueue chain lock just try again.
- */
- if (x == LK_UNLOCKED) {
- sleepq_release(&lk->lock_object);
- continue;
- }
- v = x & (LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS);
- if ((x & ~v) == LK_UNLOCKED) {
- v = (x & ~LK_EXCLUSIVE_SPINNERS);
- /*
- * If interruptible sleeps left the exclusive
- * queue empty avoid a starvation for the
- * threads sleeping on the shared queue by
- * giving them precedence and cleaning up the
- * exclusive waiters bit anyway.
- * Please note that lk_exslpfail count may be
- * lying about the real number of waiters with
- * the LK_SLEEPFAIL flag on because they may
- * be used in conjuction with interruptible
- * sleeps so lk_exslpfail might be considered
- * an 'upper limit' bound, including the edge
- * cases.
- */
- if (v & LK_EXCLUSIVE_WAITERS) {
- queue = SQ_EXCLUSIVE_QUEUE;
- v &= ~LK_EXCLUSIVE_WAITERS;
- } else {
- /*
- * Exclusive waiters sleeping with
- * LK_SLEEPFAIL on and using
- * interruptible sleeps/timeout may
- * have left spourious lk_exslpfail
- * counts on, so clean it up anyway.
- */
- MPASS(v & LK_SHARED_WAITERS);
- lk->lk_exslpfail = 0;
- queue = SQ_SHARED_QUEUE;
- v &= ~LK_SHARED_WAITERS;
- }
- if (queue == SQ_EXCLUSIVE_QUEUE) {
- realexslp =
- sleepq_sleepcnt(&lk->lock_object,
- SQ_EXCLUSIVE_QUEUE);
- if (lk->lk_exslpfail >= realexslp) {
- lk->lk_exslpfail = 0;
- queue = SQ_SHARED_QUEUE;
- v &= ~LK_SHARED_WAITERS;
- if (realexslp != 0) {
- LOCK_LOG2(lk,
- "%s: %p has only LK_SLEEPFAIL sleepers",
- __func__, lk);
- LOCK_LOG2(lk,
- "%s: %p waking up threads on the exclusive queue",
- __func__, lk);
- wakeup_swapper =
- sleepq_broadcast(
- &lk->lock_object,
- SLEEPQ_LK, 0,
- SQ_EXCLUSIVE_QUEUE);
- }
- } else
- lk->lk_exslpfail = 0;
- }
- if (!atomic_cmpset_ptr(&lk->lk_lock, x, v)) {
- sleepq_release(&lk->lock_object);
- continue;
- }
- LOCK_LOG3(lk,
- "%s: %p waking up all threads on the %s queue",
- __func__, lk, queue == SQ_SHARED_QUEUE ?
- "shared" : "exclusive");
- wakeup_swapper |= sleepq_broadcast(
- &lk->lock_object, SLEEPQ_LK, 0, queue);
- /*
- * If shared waiters have been woken up we need
- * to wait for one of them to acquire the lock
- * before to set the exclusive waiters in
- * order to avoid a deadlock.
- */
- if (queue == SQ_SHARED_QUEUE) {
- for (v = lk->lk_lock;
- (v & LK_SHARE) && !LK_SHARERS(v);
- v = lk->lk_lock)
- cpu_spinwait();
- }
- }
- /*
- * Try to set the LK_EXCLUSIVE_WAITERS flag. If we
- * fail, loop back and retry.
- */
- if ((x & LK_EXCLUSIVE_WAITERS) == 0) {
- if (!atomic_cmpset_ptr(&lk->lk_lock, x,
- x | LK_EXCLUSIVE_WAITERS)) {
- sleepq_release(&lk->lock_object);
- continue;
- }
- LOCK_LOG2(lk, "%s: %p set drain waiters flag",
- __func__, lk);
- }
- /*
- * As far as we have been unable to acquire the
- * exclusive lock and the exclusive waiters flag
- * is set, we will sleep.
- */
- if (flags & LK_INTERLOCK) {
- class->lc_unlock(ilk);
- flags &= ~LK_INTERLOCK;
- }
- GIANT_SAVE();
- sleepq_add(&lk->lock_object, NULL, iwmesg, SLEEPQ_LK,
- SQ_EXCLUSIVE_QUEUE);
- sleepq_wait(&lk->lock_object, ipri & PRIMASK);
- GIANT_RESTORE();
- LOCK_LOG2(lk, "%s: %p resuming from the sleep queue",
- __func__, lk);
- }
- if (error == 0) {
- lock_profile_obtain_lock_success(&lk->lock_object,
- contested, waittime, file, line);
- LOCK_LOG_LOCK("DRAIN", &lk->lock_object, 0,
- lk->lk_recurse, file, line);
- WITNESS_LOCK(&lk->lock_object, LOP_EXCLUSIVE |
- LK_TRYWIT(flags), file, line);
- TD_LOCKS_INC(curthread);
- STACK_SAVE(lk);
- }
- break;
- default:
- if (flags & LK_INTERLOCK)
- class->lc_unlock(ilk);
- panic("%s: unknown lockmgr request 0x%x\n", __func__, op);
- }
- if (flags & LK_INTERLOCK)
- class->lc_unlock(ilk);
- if (wakeup_swapper)
- kick_proc0();
- return (error);
- }
- void
- _lockmgr_disown(struct lock *lk, const char *file, int line)
- {
- uintptr_t tid, x;
- if (SCHEDULER_STOPPED())
- return;
- tid = (uintptr_t)curthread;
- _lockmgr_assert(lk, KA_XLOCKED | KA_NOTRECURSED, file, line);
- /*
- * If the owner is already LK_KERNPROC just skip the whole operation.
- */
- if (LK_HOLDER(lk->lk_lock) != tid)
- return;
- lock_profile_release_lock(&lk->lock_object);
- LOCK_LOG_LOCK("XDISOWN", &lk->lock_object, 0, 0, file, line);
- WITNESS_UNLOCK(&lk->lock_object, LOP_EXCLUSIVE, file, line);
- TD_LOCKS_DEC(curthread);
- STACK_SAVE(lk);
- /*
- * In order to preserve waiters flags, just spin.
- */
- for (;;) {
- x = lk->lk_lock;
- MPASS((x & LK_EXCLUSIVE_SPINNERS) == 0);
- x &= LK_ALL_WAITERS;
- if (atomic_cmpset_rel_ptr(&lk->lk_lock, tid | x,
- LK_KERNPROC | x))
- return;
- cpu_spinwait();
- }
- }
- void
- lockmgr_printinfo(const struct lock *lk)
- {
- struct thread *td;
- uintptr_t x;
- if (lk->lk_lock == LK_UNLOCKED)
- printf("lock type %s: UNLOCKED\n", lk->lock_object.lo_name);
- else if (lk->lk_lock & LK_SHARE)
- printf("lock type %s: SHARED (count %ju)\n",
- lk->lock_object.lo_name,
- (uintmax_t)LK_SHARERS(lk->lk_lock));
- else {
- td = lockmgr_xholder(lk);
- printf("lock type %s: EXCL by thread %p (pid %d)\n",
- lk->lock_object.lo_name, td, td->td_proc->p_pid);
- }
- x = lk->lk_lock;
- if (x & LK_EXCLUSIVE_WAITERS)
- printf(" with exclusive waiters pending\n");
- if (x & LK_SHARED_WAITERS)
- printf(" with shared waiters pending\n");
- if (x & LK_EXCLUSIVE_SPINNERS)
- printf(" with exclusive spinners pending\n");
- STACK_PRINT(lk);
- }
- int
- lockstatus(const struct lock *lk)
- {
- uintptr_t v, x;
- int ret;
- ret = LK_SHARED;
- x = lk->lk_lock;
- v = LK_HOLDER(x);
- if ((x & LK_SHARE) == 0) {
- if (v == (uintptr_t)curthread || v == LK_KERNPROC)
- ret = LK_EXCLUSIVE;
- else
- ret = LK_EXCLOTHER;
- } else if (x == LK_UNLOCKED)
- ret = 0;
- return (ret);
- }
- #ifdef INVARIANT_SUPPORT
- FEATURE(invariant_support,
- "Support for modules compiled with INVARIANTS option");
- #ifndef INVARIANTS
- #undef _lockmgr_assert
- #endif
- void
- _lockmgr_assert(const struct lock *lk, int what, const char *file, int line)
- {
- int slocked = 0;
- if (panicstr != NULL)
- return;
- switch (what) {
- case KA_SLOCKED:
- case KA_SLOCKED | KA_NOTRECURSED:
- case KA_SLOCKED | KA_RECURSED:
- slocked = 1;
- case KA_LOCKED:
- case KA_LOCKED | KA_NOTRECURSED:
- case KA_LOCKED | KA_RECURSED:
- #ifdef WITNESS
- /*
- * We cannot trust WITNESS if the lock is held in exclusive
- * mode and a call to lockmgr_disown() happened.
- * Workaround this skipping the check if the lock is held in
- * exclusive mode even for the KA_LOCKED case.
- */
- if (slocked || (lk->lk_lock & LK_SHARE)) {
- witness_assert(&lk->lock_object, what, file, line);
- break;
- }
- #endif
- if (lk->lk_lock == LK_UNLOCKED ||
- ((lk->lk_lock & LK_SHARE) == 0 && (slocked ||
- (!lockmgr_xlocked(lk) && !lockmgr_disowned(lk)))))
- panic("Lock %s not %slocked @ %s:%d\n",
- lk->lock_object.lo_name, slocked ? "share" : "",
- file, line);
- if ((lk->lk_lock & LK_SHARE) == 0) {
- if (lockmgr_recursed(lk)) {
- if (what & KA_NOTRECURSED)
- panic("Lock %s recursed @ %s:%d\n",
- lk->lock_object.lo_name, file,
- line);
- } else if (what & KA_RECURSED)
- panic("Lock %s not recursed @ %s:%d\n",
- lk->lock_object.lo_name, file, line);
- }
- break;
- case KA_XLOCKED:
- case KA_XLOCKED | KA_NOTRECURSED:
- case KA_XLOCKED | KA_RECURSED:
- if (!lockmgr_xlocked(lk) && !lockmgr_disowned(lk))
- panic("Lock %s not exclusively locked @ %s:%d\n",
- lk->lock_object.lo_name, file, line);
- if (lockmgr_recursed(lk)) {
- if (what & KA_NOTRECURSED)
- panic("Lock %s recursed @ %s:%d\n",
- lk->lock_object.lo_name, file, line);
- } else if (what & KA_RECURSED)
- panic("Lock %s not recursed @ %s:%d\n",
- lk->lock_object.lo_name, file, line);
- break;
- case KA_UNLOCKED:
- if (lockmgr_xlocked(lk) || lockmgr_disowned(lk))
- panic("Lock %s exclusively locked @ %s:%d\n",
- lk->lock_object.lo_name, file, line);
- break;
- default:
- panic("Unknown lockmgr assertion: %d @ %s:%d\n", what, file,
- line);
- }
- }
- #endif
- #ifdef DDB
- int
- lockmgr_chain(struct thread *td, struct thread **ownerp)
- {
- struct lock *lk;
- lk = td->td_wchan;
- if (LOCK_CLASS(&lk->lock_object) != &lock_class_lockmgr)
- return (0);
- db_printf("blocked on lockmgr %s", lk->lock_object.lo_name);
- if (lk->lk_lock & LK_SHARE)
- db_printf("SHARED (count %ju)\n",
- (uintmax_t)LK_SHARERS(lk->lk_lock));
- else
- db_printf("EXCL\n");
- *ownerp = lockmgr_xholder(lk);
- return (1);
- }
- static void
- db_show_lockmgr(const struct lock_object *lock)
- {
- struct thread *td;
- const struct lock *lk;
- lk = (const struct lock *)lock;
- db_printf(" state: ");
- if (lk->lk_lock == LK_UNLOCKED)
- db_printf("UNLOCKED\n");
- else if (lk->lk_lock & LK_SHARE)
- db_printf("SLOCK: %ju\n", (uintmax_t)LK_SHARERS(lk->lk_lock));
- else {
- td = lockmgr_xholder(lk);
- if (td == (struct thread *)LK_KERNPROC)
- db_printf("XLOCK: LK_KERNPROC\n");
- else
- db_printf("XLOCK: %p (tid %d, pid %d, \"%s\")\n", td,
- td->td_tid, td->td_proc->p_pid,
- td->td_proc->p_comm);
- if (lockmgr_recursed(lk))
- db_printf(" recursed: %d\n", lk->lk_recurse);
- }
- db_printf(" waiters: ");
- switch (lk->lk_lock & LK_ALL_WAITERS) {
- case LK_SHARED_WAITERS:
- db_printf("shared\n");
- break;
- case LK_EXCLUSIVE_WAITERS:
- db_printf("exclusive\n");
- break;
- case LK_ALL_WAITERS:
- db_printf("shared and exclusive\n");
- break;
- default:
- db_printf("none\n");
- }
- db_printf(" spinners: ");
- if (lk->lk_lock & LK_EXCLUSIVE_SPINNERS)
- db_printf("exclusive\n");
- else
- db_printf("none\n");
- }
- #endif