diff options
Diffstat (limited to 'sys/kern/kern_mutex.c')
| -rw-r--r-- | sys/kern/kern_mutex.c | 948 |
1 files changed, 402 insertions, 546 deletions
diff --git a/sys/kern/kern_mutex.c b/sys/kern/kern_mutex.c index c13dd1d..64d3972 100644 --- a/sys/kern/kern_mutex.c +++ b/sys/kern/kern_mutex.c @@ -31,6 +31,11 @@ */ /* + * Machine independent bits of mutex implementation and implementation of + * `witness' structure & related debugging routines. + */ + +/* * Main Entry: witness * Pronunciation: 'wit-n&s * Function: noun @@ -53,12 +58,6 @@ #include "opt_ddb.h" #include "opt_witness.h" -/* - * Cause non-inlined mtx_*() to be compiled. - * Must be defined early because other system headers may include mutex.h. - */ -#define _KERN_MUTEX_C_ - #include <sys/param.h> #include <sys/bus.h> #include <sys/kernel.h> @@ -82,9 +81,8 @@ #include <sys/mutex.h> /* - * Machine independent bits of the mutex implementation + * The WITNESS-enabled mutex debug structure. */ - #ifdef WITNESS struct mtx_debug { struct witness *mtxd_witness; @@ -100,138 +98,54 @@ struct mtx_debug { #endif /* WITNESS */ /* - * Assembly macros - *------------------------------------------------------------------------------ - */ - -#define _V(x) __STRING(x) - -/* - * Default, unoptimized mutex micro-operations + * Internal utility macros. */ +#define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED) -#ifndef _obtain_lock -/* Actually obtain mtx_lock */ -#define _obtain_lock(mp, tid) \ - atomic_cmpset_acq_ptr(&(mp)->mtx_lock, (void *)MTX_UNOWNED, (tid)) -#endif - -#ifndef _release_lock -/* Actually release mtx_lock */ -#define _release_lock(mp, tid) \ - atomic_cmpset_rel_ptr(&(mp)->mtx_lock, (tid), (void *)MTX_UNOWNED) -#endif - -#ifndef _release_lock_quick -/* Actually release mtx_lock quickly assuming that we own it */ -#define _release_lock_quick(mp) \ - atomic_store_rel_ptr(&(mp)->mtx_lock, (void *)MTX_UNOWNED) -#endif - -#ifndef _getlock_sleep -/* Get a sleep lock, deal with recursion inline. */ -#define _getlock_sleep(mp, tid, type) do { \ - if (!_obtain_lock(mp, tid)) { \ - if (((mp)->mtx_lock & MTX_FLAGMASK) != ((uintptr_t)(tid)))\ - mtx_enter_hard(mp, (type) & MTX_HARDOPTS, 0); \ - else { \ - atomic_set_ptr(&(mp)->mtx_lock, MTX_RECURSED); \ - (mp)->mtx_recurse++; \ - } \ - } \ -} while (0) -#endif - -#ifndef _getlock_spin_block -/* Get a spin lock, handle recursion inline (as the less common case) */ -#define _getlock_spin_block(mp, tid, type) do { \ - u_int _mtx_intr = save_intr(); \ - disable_intr(); \ - if (!_obtain_lock(mp, tid)) \ - mtx_enter_hard(mp, (type) & MTX_HARDOPTS, _mtx_intr); \ - else \ - (mp)->mtx_saveintr = _mtx_intr; \ -} while (0) -#endif +#define mtx_owner(m) (mtx_unowned((m)) ? NULL \ + : (struct proc *)((m)->mtx_lock & MTX_FLAGMASK)) -#ifndef _getlock_norecurse -/* - * Get a lock without any recursion handling. Calls the hard enter function if - * we can't get it inline. - */ -#define _getlock_norecurse(mp, tid, type) do { \ - if (!_obtain_lock(mp, tid)) \ - mtx_enter_hard((mp), (type) & MTX_HARDOPTS, 0); \ -} while (0) -#endif +#define RETIP(x) *(((uintptr_t *)(&x)) - 1) +#define SET_PRIO(p, pri) (p)->p_priority = (pri) -#ifndef _exitlock_norecurse /* - * Release a sleep lock assuming we haven't recursed on it, recursion is handled - * in the hard function. + * Early WITNESS-enabled declarations. */ -#define _exitlock_norecurse(mp, tid, type) do { \ - if (!_release_lock(mp, tid)) \ - mtx_exit_hard((mp), (type) & MTX_HARDOPTS); \ -} while (0) -#endif +#ifdef WITNESS -#ifndef _exitlock /* - * Release a sleep lock when its likely we recursed (the code to - * deal with simple recursion is inline). - */ -#define _exitlock(mp, tid, type) do { \ - if (!_release_lock(mp, tid)) { \ - if ((mp)->mtx_lock & MTX_RECURSED) { \ - if (--((mp)->mtx_recurse) == 0) \ - atomic_clear_ptr(&(mp)->mtx_lock, \ - MTX_RECURSED); \ - } else { \ - mtx_exit_hard((mp), (type) & MTX_HARDOPTS); \ - } \ - } \ -} while (0) -#endif - -#ifndef _exitlock_spin -/* Release a spin lock (with possible recursion). */ -#define _exitlock_spin(mp) do { \ - if (!mtx_recursed((mp))) { \ - int _mtx_intr = (mp)->mtx_saveintr; \ - \ - _release_lock_quick(mp); \ - restore_intr(_mtx_intr); \ - } else { \ - (mp)->mtx_recurse--; \ - } \ -} while (0) -#endif + * Internal WITNESS routines which must be prototyped early. + * + * XXX: When/if witness code is cleaned up, it would be wise to place all + * witness prototyping early in this file. + */ +static void witness_init(struct mtx *, int flag); +static void witness_destroy(struct mtx *); +static void witness_display(void(*)(const char *fmt, ...)); -#ifdef WITNESS -static void witness_init(struct mtx *, int flag); -static void witness_destroy(struct mtx *); -static void witness_display(void(*)(const char *fmt, ...)); +MALLOC_DEFINE(M_WITNESS, "witness", "witness mtx_debug structure"); /* All mutexes in system (used for debug/panic) */ static struct mtx_debug all_mtx_debug = { NULL, {NULL, NULL}, NULL, 0 }; + /* - * Set to 0 once mutexes have been fully initialized so that witness code can be - * safely executed. + * This global is set to 0 once it becomes safe to use the witness code. */ static int witness_cold = 1; + #else /* WITNESS */ -/* - * flag++ is slezoid way of shutting up unused parameter warning - * in mtx_init() +/* XXX XXX XXX + * flag++ is sleazoid way of shuting up warning */ #define witness_init(m, flag) flag++ #define witness_destroy(m) #define witness_try_enter(m, t, f, l) #endif /* WITNESS */ -/* All mutexes in system (used for debug/panic) */ +/* + * All mutex locks in system are kept on the all_mtx list. + */ static struct mtx all_mtx = { MTX_UNOWNED, 0, 0, 0, "All mutexes queue head", TAILQ_HEAD_INITIALIZER(all_mtx.mtx_blocked), { NULL, NULL }, &all_mtx, &all_mtx, @@ -242,19 +156,18 @@ static struct mtx all_mtx = { MTX_UNOWNED, 0, 0, 0, "All mutexes queue head", #endif }; +/* + * Global variables for book keeping. + */ static int mtx_cur_cnt; static int mtx_max_cnt; +/* + * Prototypes for non-exported routines. + * + * NOTE: Prototypes for witness routines are placed at the bottom of the file. + */ static void propagate_priority(struct proc *); -static void mtx_enter_hard(struct mtx *, int type, int saveintr); -static void mtx_exit_hard(struct mtx *, int type); - -#define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED) -#define mtx_owner(m) (mtx_unowned(m) ? NULL \ - : (struct proc *)((m)->mtx_lock & MTX_FLAGMASK)) - -#define RETIP(x) *(((uintptr_t *)(&x)) - 1) -#define SET_PRIO(p, pri) (p)->p_priority = (pri) static void propagate_priority(struct proc *p) @@ -277,6 +190,7 @@ propagate_priority(struct proc *p) MPASS(m->mtx_lock == MTX_CONTESTED); return; } + MPASS(p->p_magic == P_MAGIC); KASSERT(p->p_stat != SSLEEP, ("sleeping process owns a mutex")); if (p->p_priority <= pri) @@ -314,7 +228,7 @@ propagate_priority(struct proc *p) * quit. */ if (p->p_stat == SRUN) { - printf("XXX: moving process %d(%s) to a new run queue\n", + printf("XXX: moving proc %d(%s) to a new run queue\n", p->p_pid, p->p_comm); MPASS(p->p_blocked == NULL); remrunqueue(p); @@ -338,6 +252,7 @@ propagate_priority(struct proc *p) printf("XXX: process %d(%s) is blocked on %s\n", p->p_pid, p->p_comm, m->mtx_description); + /* * Check if the proc needs to be moved up on * the blocked chain @@ -346,10 +261,11 @@ propagate_priority(struct proc *p) printf("XXX: process at head of run queue\n"); continue; } + p1 = TAILQ_PREV(p, rq, p_procq); if (p1->p_priority <= pri) { printf( - "XXX: previous process %d(%s) has higher priority\n", + "XXX: previous process %d(%s) has higher priority\n", p->p_pid, p->p_comm); continue; } @@ -367,6 +283,7 @@ propagate_priority(struct proc *p) if (p1->p_priority > pri) break; } + MPASS(p1 != NULL); TAILQ_INSERT_BEFORE(p1, p, p_procq); CTR4(KTR_LOCK, @@ -376,421 +293,332 @@ propagate_priority(struct proc *p) } /* - * Get lock 'm', the macro handles the easy (and most common cases) and leaves - * the slow stuff to the mtx_enter_hard() function. - * - * Note: since type is usually a constant much of this code is optimized out. + * The important part of mtx_trylock{,_flags}() + * Tries to acquire lock `m.' We do NOT handle recursion here; we assume that + * if we're called, it's because we know we don't already own this lock. */ -void -_mtx_enter(struct mtx *mtxp, int type, const char *file, int line) +int +_mtx_trylock(struct mtx *m, int opts, const char *file, int line) { - struct mtx *mpp = mtxp; + int rval; - /* bits only valid on mtx_exit() */ - MPASS4(((type) & (MTX_NORECURSE | MTX_NOSWITCH)) == 0, - STR_mtx_bad_type, file, line); + KASSERT(CURPROC != NULL, ("curproc is NULL in _mtx_trylock")); - if ((type) & MTX_SPIN) { - /* - * Easy cases of spin locks: - * - * 1) We already own the lock and will simply recurse on it (if - * RLIKELY) - * - * 2) The lock is free, we just get it - */ - if ((type) & MTX_RLIKELY) { - /* - * Check for recursion, if we already have this - * lock we just bump the recursion count. - */ - if (mpp->mtx_lock == (uintptr_t)CURTHD) { - mpp->mtx_recurse++; - goto done; - } - } - - if (((type) & MTX_TOPHALF) == 0) { - /* - * If an interrupt thread uses this we must block - * interrupts here. - */ - if ((type) & MTX_FIRST) { - ASS_IEN; - disable_intr(); - _getlock_norecurse(mpp, CURTHD, - (type) & MTX_HARDOPTS); - } else { - _getlock_spin_block(mpp, CURTHD, - (type) & MTX_HARDOPTS); - } - } else - _getlock_norecurse(mpp, CURTHD, (type) & MTX_HARDOPTS); - } else { - /* Sleep locks */ - if ((type) & MTX_RLIKELY) - _getlock_sleep(mpp, CURTHD, (type) & MTX_HARDOPTS); - else - _getlock_norecurse(mpp, CURTHD, (type) & MTX_HARDOPTS); - } -done: - WITNESS_ENTER(mpp, type, file, line); - if (((type) & MTX_QUIET) == 0) - CTR5(KTR_LOCK, STR_mtx_enter_fmt, - mpp->mtx_description, mpp, mpp->mtx_recurse, file, line); - -} + /* + * _mtx_trylock does not accept MTX_NOSWITCH option. + */ + MPASS((opts & MTX_NOSWITCH) == 0); -/* - * Attempt to get MTX_DEF lock, return non-zero if lock acquired. - * - * XXX DOES NOT HANDLE RECURSION - */ -int -_mtx_try_enter(struct mtx *mtxp, int type, const char *file, int line) -{ - struct mtx *const mpp = mtxp; - int rval; + rval = _obtain_lock(m, CURTHD); - rval = _obtain_lock(mpp, CURTHD); #ifdef WITNESS - if (rval && mpp->mtx_witness != NULL) { - MPASS(mpp->mtx_recurse == 0); - witness_try_enter(mpp, type, file, line); + if (rval && m->mtx_witness != NULL) { + /* + * We do not handle recursion in _mtx_trylock; see the + * note at the top of the routine. + */ + MPASS(!mtx_recursed(m)); + witness_try_enter(m, (opts | m->mtx_flags), file, line); } #endif /* WITNESS */ - if (((type) & MTX_QUIET) == 0) - CTR5(KTR_LOCK, STR_mtx_try_enter_fmt, - mpp->mtx_description, mpp, rval, file, line); + + if ((opts & MTX_QUIET) == 0) + CTR5(KTR_LOCK, "TRY_ENTER %s [%p] result=%d at %s:%d", + m->mtx_description, m, rval, file, line); return rval; } /* - * Release lock m. + * _mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock. + * + * We call this if the lock is either contested (i.e. we need to go to + * sleep waiting for it), or if we need to recurse on it. */ void -_mtx_exit(struct mtx *mtxp, int type, const char *file, int line) +_mtx_lock_sleep(struct mtx *m, int opts, const char *file, int line) { - struct mtx *const mpp = mtxp; - - MPASS4(mtx_owned(mpp), STR_mtx_owned, file, line); - WITNESS_EXIT(mpp, type, file, line); - if (((type) & MTX_QUIET) == 0) - CTR5(KTR_LOCK, STR_mtx_exit_fmt, - mpp->mtx_description, mpp, mpp->mtx_recurse, file, line); - if ((type) & MTX_SPIN) { - if ((type) & MTX_NORECURSE) { - int mtx_intr = mpp->mtx_saveintr; - - MPASS4(mpp->mtx_recurse == 0, STR_mtx_recurse, - file, line); - _release_lock_quick(mpp); - if (((type) & MTX_TOPHALF) == 0) { - if ((type) & MTX_FIRST) { - ASS_IDIS; - enable_intr(); - } else - restore_intr(mtx_intr); - } - } else { - if (((type & MTX_TOPHALF) == 0) && - (type & MTX_FIRST)) { - ASS_IDIS; - ASS_SIEN(mpp); - } - _exitlock_spin(mpp); - } - } else { - /* Handle sleep locks */ - if ((type) & MTX_RLIKELY) - _exitlock(mpp, CURTHD, (type) & MTX_HARDOPTS); - else { - _exitlock_norecurse(mpp, CURTHD, - (type) & MTX_HARDOPTS); - } + struct proc *p = CURPROC; + + if ((m->mtx_lock & MTX_FLAGMASK) == (uintptr_t)p) { + m->mtx_recurse++; + atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); + if ((opts & MTX_QUIET) == 0) + CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recurse", m); + return; } -} -void -mtx_enter_hard(struct mtx *m, int type, int saveintr) -{ - struct proc *p = CURPROC; + if ((opts & MTX_QUIET) == 0) + CTR3(KTR_LOCK, "mtx_lock: %p contested (lock=%p) [%p]", m, + (void *)m->mtx_lock, (void *)RETIP(m)); + + /* + * Save our priority. Even though p_nativepri is protected by + * sched_lock, we don't obtain it here as it can be expensive. + * Since this is the only place p_nativepri is set, and since two + * CPUs will not be executing the same process concurrently, we know + * that no other CPU is going to be messing with this. Also, + * p_nativepri is only read when we are blocked on a mutex, so that + * can't be happening right now either. + */ + p->p_nativepri = p->p_priority; - KASSERT(p != NULL, ("curproc is NULL in mutex")); + while (!_obtain_lock(m, p)) { + uintptr_t v; + struct proc *p1; - switch (type) { - case MTX_DEF: - if ((m->mtx_lock & MTX_FLAGMASK) == (uintptr_t)p) { - m->mtx_recurse++; - atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); - if ((type & MTX_QUIET) == 0) - CTR1(KTR_LOCK, "mtx_enter: %p recurse", m); - return; + mtx_lock_spin(&sched_lock); + /* + * Check if the lock has been released while spinning for + * the sched_lock. + */ + if ((v = m->mtx_lock) == MTX_UNOWNED) { + mtx_unlock_spin(&sched_lock); + continue; } - if ((type & MTX_QUIET) == 0) - CTR3(KTR_LOCK, - "mtx_enter: %p contested (lock=%p) [%p]", - m, (void *)m->mtx_lock, (void *)RETIP(m)); /* - * Save our priority. Even though p_nativepri is protected - * by sched_lock, we don't obtain it here as it can be - * expensive. Since this is the only place p_nativepri is - * set, and since two CPUs will not be executing the same - * process concurrently, we know that no other CPU is going - * to be messing with this. Also, p_nativepri is only read - * when we are blocked on a mutex, so that can't be happening - * right now either. + * The mutex was marked contested on release. This means that + * there are processes blocked on it. */ - p->p_nativepri = p->p_priority; - while (!_obtain_lock(m, p)) { - uintptr_t v; - struct proc *p1; + if (v == MTX_CONTESTED) { + p1 = TAILQ_FIRST(&m->mtx_blocked); + KASSERT(p1 != NULL, + ("contested mutex has no contesters")); + m->mtx_lock = (uintptr_t)p | MTX_CONTESTED; + + if (p1->p_priority < p->p_priority) + SET_PRIO(p, p1->p_priority); + mtx_unlock_spin(&sched_lock); + return; + } - mtx_enter(&sched_lock, MTX_SPIN | MTX_RLIKELY); - /* - * check if the lock has been released while - * waiting for the schedlock. - */ - if ((v = m->mtx_lock) == MTX_UNOWNED) { - mtx_exit(&sched_lock, MTX_SPIN); - continue; - } - /* - * The mutex was marked contested on release. This - * means that there are processes blocked on it. - */ - if (v == MTX_CONTESTED) { - p1 = TAILQ_FIRST(&m->mtx_blocked); - KASSERT(p1 != NULL, ("contested mutex has no contesters")); - KASSERT(p != NULL, ("curproc is NULL for contested mutex")); - m->mtx_lock = (uintptr_t)p | MTX_CONTESTED; - if (p1->p_priority < p->p_priority) { - SET_PRIO(p, p1->p_priority); - } - mtx_exit(&sched_lock, MTX_SPIN); - return; - } - /* - * If the mutex isn't already contested and - * a failure occurs setting the contested bit the - * mutex was either release or the - * state of the RECURSION bit changed. - */ - if ((v & MTX_CONTESTED) == 0 && - !atomic_cmpset_ptr(&m->mtx_lock, (void *)v, - (void *)(v | MTX_CONTESTED))) { - mtx_exit(&sched_lock, MTX_SPIN); - continue; - } + /* + * If the mutex isn't already contested and a failure occurs + * setting the contested bit, the mutex was either released + * or the state of the MTX_RECURSED bit changed. + */ + if ((v & MTX_CONTESTED) == 0 && + !atomic_cmpset_ptr(&m->mtx_lock, (void *)v, + (void *)(v | MTX_CONTESTED))) { + mtx_unlock_spin(&sched_lock); + continue; + } - /* We definitely have to sleep for this lock */ - mtx_assert(m, MA_NOTOWNED); + /* + * We deffinately must sleep for this lock. + */ + mtx_assert(m, MA_NOTOWNED); #ifdef notyet - /* - * If we're borrowing an interrupted thread's VM - * context must clean up before going to sleep. - */ - if (p->p_flag & (P_ITHD | P_SITHD)) { - ithd_t *it = (ithd_t *)p; - - if (it->it_interrupted) { - if ((type & MTX_QUIET) == 0) - CTR2(KTR_LOCK, - "mtx_enter: 0x%x interrupted 0x%x", - it, it->it_interrupted); - intr_thd_fixup(it); - } + /* + * If we're borrowing an interrupted thread's VM context, we + * must clean up before going to sleep. + */ + if (p->p_flag & (P_ITHD | P_SITHD)) { + ithd_t *it = (ithd_t *)p; + + if (it->it_interrupted) { + if ((opts & MTX_QUIET) == 0) + CTR2(KTR_LOCK, + "mtx_lock: 0x%x interrupted 0x%x", + it, it->it_interrupted); + intr_thd_fixup(it); } + } #endif - /* Put us on the list of procs blocked on this mutex */ - if (TAILQ_EMPTY(&m->mtx_blocked)) { - p1 = (struct proc *)(m->mtx_lock & - MTX_FLAGMASK); - LIST_INSERT_HEAD(&p1->p_contested, m, - mtx_contested); + /* + * Put us on the list of threads blocked on this mutex. + */ + if (TAILQ_EMPTY(&m->mtx_blocked)) { + p1 = (struct proc *)(m->mtx_lock & MTX_FLAGMASK); + LIST_INSERT_HEAD(&p1->p_contested, m, mtx_contested); + TAILQ_INSERT_TAIL(&m->mtx_blocked, p, p_procq); + } else { + TAILQ_FOREACH(p1, &m->mtx_blocked, p_procq) + if (p1->p_priority > p->p_priority) + break; + if (p1) + TAILQ_INSERT_BEFORE(p1, p, p_procq); + else TAILQ_INSERT_TAIL(&m->mtx_blocked, p, p_procq); - } else { - TAILQ_FOREACH(p1, &m->mtx_blocked, p_procq) - if (p1->p_priority > p->p_priority) - break; - if (p1) - TAILQ_INSERT_BEFORE(p1, p, p_procq); - else - TAILQ_INSERT_TAIL(&m->mtx_blocked, p, - p_procq); - } + } - p->p_blocked = m; /* Who we're blocked on */ - p->p_mtxname = m->mtx_description; - p->p_stat = SMTX; + /* + * Save who we're blocked on. + */ + p->p_blocked = m; + p->p_mtxname = m->mtx_description; + p->p_stat = SMTX; #if 0 - propagate_priority(p); + propagate_priority(p); #endif - if ((type & MTX_QUIET) == 0) - CTR3(KTR_LOCK, - "mtx_enter: p %p blocked on [%p] %s", - p, m, m->mtx_description); - mi_switch(); - if ((type & MTX_QUIET) == 0) - CTR3(KTR_LOCK, - "mtx_enter: p %p free from blocked on [%p] %s", - p, m, m->mtx_description); - mtx_exit(&sched_lock, MTX_SPIN); - } - return; - case MTX_SPIN: - case MTX_SPIN | MTX_FIRST: - case MTX_SPIN | MTX_TOPHALF: - { - int i = 0; - - if (m->mtx_lock == (uintptr_t)p) { - m->mtx_recurse++; - return; - } - if ((type & MTX_QUIET) == 0) - CTR1(KTR_LOCK, "mtx_enter: %p spinning", m); - for (;;) { - if (_obtain_lock(m, p)) - break; - while (m->mtx_lock != MTX_UNOWNED) { - if (i++ < 1000000) - continue; - if (i++ < 6000000) - DELAY (1); + + if ((opts & MTX_QUIET) == 0) + CTR3(KTR_LOCK, + "_mtx_lock_sleep: p %p blocked on [%p] %s", p, m, + m->mtx_description); + + mi_switch(); + + if ((opts & MTX_QUIET) == 0) + CTR3(KTR_LOCK, + "_mtx_lock_sleep: p %p free from blocked on [%p] %s", + p, m, m->mtx_description); + + mtx_unlock_spin(&sched_lock); + } + + return; +} + +/* + * _mtx_lock_spin: the tougher part of acquiring an MTX_SPIN lock. + * + * This is only called if we need to actually spin for the lock. Recursion + * is handled inline. + */ +void +_mtx_lock_spin(struct mtx *m, int opts, u_int mtx_intr, const char *file, + int line) +{ + int i = 0; + + if ((opts & MTX_QUIET) == 0) + CTR1(KTR_LOCK, "mtx_lock_spin: %p spinning", m); + + for (;;) { + if (_obtain_lock(m, CURPROC)) + break; + + while (m->mtx_lock != MTX_UNOWNED) { + if (i++ < 1000000) + continue; + if (i++ < 6000000) + DELAY(1); #ifdef DDB - else if (!db_active) + else if (!db_active) #else - else + else #endif - panic( - "spin lock %s held by %p for > 5 seconds", - m->mtx_description, - (void *)m->mtx_lock); - } + panic("spin lock %s held by %p for > 5 seconds", + m->mtx_description, (void *)m->mtx_lock); } - -#ifdef MUTEX_DEBUG - if (type != MTX_SPIN) - m->mtx_saveintr = 0xbeefface; - else -#endif - m->mtx_saveintr = saveintr; - if ((type & MTX_QUIET) == 0) - CTR1(KTR_LOCK, "mtx_enter: %p spin done", m); - return; - } } + + m->mtx_saveintr = mtx_intr; + if ((opts & MTX_QUIET) == 0) + CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m); + + return; } +/* + * _mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock. + * + * We are only called here if the lock is recursed or contested (i.e. we + * need to wake up a blocked thread). + */ void -mtx_exit_hard(struct mtx *m, int type) +_mtx_unlock_sleep(struct mtx *m, int opts, const char *file, int line) { struct proc *p, *p1; struct mtx *m1; int pri; p = CURPROC; - switch (type) { - case MTX_DEF: - case MTX_DEF | MTX_NOSWITCH: - if (mtx_recursed(m)) { - if (--(m->mtx_recurse) == 0) - atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED); - if ((type & MTX_QUIET) == 0) - CTR1(KTR_LOCK, "mtx_exit: %p unrecurse", m); - return; - } - mtx_enter(&sched_lock, MTX_SPIN); - if ((type & MTX_QUIET) == 0) - CTR1(KTR_LOCK, "mtx_exit: %p contested", m); - p1 = TAILQ_FIRST(&m->mtx_blocked); - MPASS(p->p_magic == P_MAGIC); - MPASS(p1->p_magic == P_MAGIC); - TAILQ_REMOVE(&m->mtx_blocked, p1, p_procq); - if (TAILQ_EMPTY(&m->mtx_blocked)) { - LIST_REMOVE(m, mtx_contested); - _release_lock_quick(m); - if ((type & MTX_QUIET) == 0) - CTR1(KTR_LOCK, "mtx_exit: %p not held", m); - } else - atomic_store_rel_ptr(&m->mtx_lock, - (void *)MTX_CONTESTED); - pri = MAXPRI; - LIST_FOREACH(m1, &p->p_contested, mtx_contested) { - int cp = TAILQ_FIRST(&m1->mtx_blocked)->p_priority; - if (cp < pri) - pri = cp; - } - if (pri > p->p_nativepri) - pri = p->p_nativepri; - SET_PRIO(p, pri); - if ((type & MTX_QUIET) == 0) - CTR2(KTR_LOCK, - "mtx_exit: %p contested setrunqueue %p", m, p1); - p1->p_blocked = NULL; - p1->p_mtxname = NULL; - p1->p_stat = SRUN; - setrunqueue(p1); - if ((type & MTX_NOSWITCH) == 0 && p1->p_priority < pri) { + MPASS4(mtx_owned(m), "mtx_owned(mpp)", file, line); + + if ((opts & MTX_QUIET) == 0) + CTR5(KTR_LOCK, "REL %s [%p] r=%d at %s:%d", m->mtx_description, + m, m->mtx_recurse, file, line); + + if (mtx_recursed(m)) { + if (--(m->mtx_recurse) == 0) + atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED); + if ((opts & MTX_QUIET) == 0) + CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m); + return; + } + + mtx_lock_spin(&sched_lock); + if ((opts & MTX_QUIET) == 0) + CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m); + + p1 = TAILQ_FIRST(&m->mtx_blocked); + MPASS(p->p_magic == P_MAGIC); + MPASS(p1->p_magic == P_MAGIC); + + TAILQ_REMOVE(&m->mtx_blocked, p1, p_procq); + + if (TAILQ_EMPTY(&m->mtx_blocked)) { + LIST_REMOVE(m, mtx_contested); + _release_lock_quick(m); + if ((opts & MTX_QUIET) == 0) + CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p not held", m); + } else + atomic_store_rel_ptr(&m->mtx_lock, (void *)MTX_CONTESTED); + + pri = MAXPRI; + LIST_FOREACH(m1, &p->p_contested, mtx_contested) { + int cp = TAILQ_FIRST(&m1->mtx_blocked)->p_priority; + if (cp < pri) + pri = cp; + } + + if (pri > p->p_nativepri) + pri = p->p_nativepri; + SET_PRIO(p, pri); + + if ((opts & MTX_QUIET) == 0) + CTR2(KTR_LOCK, "_mtx_unlock_sleep: %p contested setrunqueue %p", + m, p1); + + p1->p_blocked = NULL; + p1->p_mtxname = NULL; + p1->p_stat = SRUN; + setrunqueue(p1); + + if ((opts & MTX_NOSWITCH) == 0 && p1->p_priority < pri) { #ifdef notyet - if (p->p_flag & (P_ITHD | P_SITHD)) { - ithd_t *it = (ithd_t *)p; - - if (it->it_interrupted) { - if ((type & MTX_QUIET) == 0) - CTR2(KTR_LOCK, - "mtx_exit: 0x%x interruped 0x%x", - it, it->it_interrupted); - intr_thd_fixup(it); - } + if (p->p_flag & (P_ITHD | P_SITHD)) { + ithd_t *it = (ithd_t *)p; + + if (it->it_interrupted) { + if ((opts & MTX_QUIET) == 0) + CTR2(KTR_LOCK, + "_mtx_unlock_sleep: 0x%x interrupted 0x%x", + it, it->it_interrupted); + intr_thd_fixup(it); } -#endif - setrunqueue(p); - if ((type & MTX_QUIET) == 0) - CTR2(KTR_LOCK, - "mtx_exit: %p switching out lock=%p", - m, (void *)m->mtx_lock); - mi_switch(); - if ((type & MTX_QUIET) == 0) - CTR2(KTR_LOCK, - "mtx_exit: %p resuming lock=%p", - m, (void *)m->mtx_lock); } - mtx_exit(&sched_lock, MTX_SPIN); - break; - case MTX_SPIN: - case MTX_SPIN | MTX_FIRST: - if (mtx_recursed(m)) { - m->mtx_recurse--; - return; - } - MPASS(mtx_owned(m)); - _release_lock_quick(m); - if (type & MTX_FIRST) - enable_intr(); /* XXX is this kosher? */ - else { - MPASS(m->mtx_saveintr != 0xbeefface); - restore_intr(m->mtx_saveintr); - } - break; - case MTX_SPIN | MTX_TOPHALF: - if (mtx_recursed(m)) { - m->mtx_recurse--; - return; - } - MPASS(mtx_owned(m)); - _release_lock_quick(m); - break; - default: - panic("mtx_exit_hard: unsupported type 0x%x\n", type); +#endif + setrunqueue(p); + if ((opts & MTX_QUIET) == 0) + CTR2(KTR_LOCK, + "_mtx_unlock_sleep: %p switching out lock=%p", m, + (void *)m->mtx_lock); + + mi_switch(); + if ((opts & MTX_QUIET) == 0) + CTR2(KTR_LOCK, "_mtx_unlock_sleep: %p resuming lock=%p", + m, (void *)m->mtx_lock); } + + mtx_unlock_spin(&sched_lock); + + return; } +/* + * All the unlocking of MTX_SPIN locks is done inline. + * See the _rel_spin_lock() macro for the details. + */ + +/* + * The INVARIANTS-enabled mtx_assert() + */ #ifdef INVARIANTS void _mtx_assert(struct mtx *m, int what, const char *file, int line) @@ -822,6 +650,9 @@ _mtx_assert(struct mtx *m, int what, const char *file, int line) } #endif +/* + * The MUTEX_DEBUG-enabled mtx_validate() + */ #define MV_DESTROY 0 /* validate before destory */ #define MV_INIT 1 /* validate before init */ @@ -843,7 +674,7 @@ mtx_validate(struct mtx *m, int when) if (m == &all_mtx || cold) return 0; - mtx_enter(&all_mtx, MTX_DEF); + mtx_lock(&all_mtx); /* * XXX - When kernacc() is fixed on the alpha to handle K0_SEG memory properly * we can re-enable the kernacc() checks. @@ -887,50 +718,63 @@ mtx_validate(struct mtx *m, int when) retval = 1; } } - mtx_exit(&all_mtx, MTX_DEF); + mtx_unlock(&all_mtx); return (retval); } #endif +/* + * Mutex initialization routine; initialize lock `m' of type contained in + * `opts' with options contained in `opts' and description `description.' + * Place on "all_mtx" queue. + */ void -mtx_init(struct mtx *m, const char *t, int flag) +mtx_init(struct mtx *m, const char *description, int opts) { - if ((flag & MTX_QUIET) == 0) - CTR2(KTR_LOCK, "mtx_init %p (%s)", m, t); + + if ((opts & MTX_QUIET) == 0) + CTR2(KTR_LOCK, "mtx_init %p (%s)", m, description); + #ifdef MUTEX_DEBUG - if (mtx_validate(m, MV_INIT)) /* diagnostic and error correction */ + /* Diagnostic and error correction */ + if (mtx_validate(m, MV_INIT)) return; #endif bzero((void *)m, sizeof *m); TAILQ_INIT(&m->mtx_blocked); + #ifdef WITNESS if (!witness_cold) { - /* XXX - should not use DEVBUF */ m->mtx_debug = malloc(sizeof(struct mtx_debug), - M_DEVBUF, M_NOWAIT | M_ZERO); + M_WITNESS, M_NOWAIT | M_ZERO); MPASS(m->mtx_debug != NULL); } #endif - m->mtx_description = t; - m->mtx_flags = flag; + m->mtx_description = description; + m->mtx_flags = opts; m->mtx_lock = MTX_UNOWNED; + /* Put on all mutex queue */ - mtx_enter(&all_mtx, MTX_DEF); + mtx_lock(&all_mtx); m->mtx_next = &all_mtx; m->mtx_prev = all_mtx.mtx_prev; m->mtx_prev->mtx_next = m; all_mtx.mtx_prev = m; if (++mtx_cur_cnt > mtx_max_cnt) mtx_max_cnt = mtx_cur_cnt; - mtx_exit(&all_mtx, MTX_DEF); + mtx_unlock(&all_mtx); + #ifdef WITNESS if (!witness_cold) - witness_init(m, flag); + witness_init(m, opts); #endif } +/* + * Remove lock `m' from all_mtx queue. + */ void mtx_destroy(struct mtx *m) { @@ -939,7 +783,9 @@ mtx_destroy(struct mtx *m) KASSERT(!witness_cold, ("%s: Cannot destroy while still cold\n", __FUNCTION__)); #endif + CTR2(KTR_LOCK, "mtx_destroy %p (%s)", m, m->mtx_description); + #ifdef MUTEX_DEBUG if (m->mtx_next == NULL) panic("mtx_destroy: %p (%s) already destroyed", @@ -950,7 +796,9 @@ mtx_destroy(struct mtx *m) } else { MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0); } - mtx_validate(m, MV_DESTROY); /* diagnostic */ + + /* diagnostic */ + mtx_validate(m, MV_DESTROY); #endif #ifdef WITNESS @@ -959,25 +807,27 @@ mtx_destroy(struct mtx *m) #endif /* WITNESS */ /* Remove from the all mutex queue */ - mtx_enter(&all_mtx, MTX_DEF); + mtx_lock(&all_mtx); m->mtx_next->mtx_prev = m->mtx_prev; m->mtx_prev->mtx_next = m->mtx_next; + #ifdef MUTEX_DEBUG m->mtx_next = m->mtx_prev = NULL; #endif + #ifdef WITNESS - free(m->mtx_debug, M_DEVBUF); + free(m->mtx_debug, M_WITNESS); m->mtx_debug = NULL; #endif + mtx_cur_cnt--; - mtx_exit(&all_mtx, MTX_DEF); + mtx_unlock(&all_mtx); } + /* - * The non-inlined versions of the mtx_*() functions are always built (above), - * but the witness code depends on the WITNESS kernel option being specified. + * The WITNESS-enabled diagnostic code. */ - #ifdef WITNESS static void witness_fixup(void *dummy __unused) @@ -988,26 +838,26 @@ witness_fixup(void *dummy __unused) * We have to release Giant before initializing its witness * structure so that WITNESS doesn't get confused. */ - mtx_exit(&Giant, MTX_DEF); + mtx_unlock(&Giant); mtx_assert(&Giant, MA_NOTOWNED); - mtx_enter(&all_mtx, MTX_DEF); + + mtx_lock(&all_mtx); /* Iterate through all mutexes and finish up mutex initialization. */ for (mp = all_mtx.mtx_next; mp != &all_mtx; mp = mp->mtx_next) { - /* XXX - should not use DEVBUF */ mp->mtx_debug = malloc(sizeof(struct mtx_debug), - M_DEVBUF, M_NOWAIT | M_ZERO); + M_WITNESS, M_NOWAIT | M_ZERO); MPASS(mp->mtx_debug != NULL); witness_init(mp, mp->mtx_flags); } - mtx_exit(&all_mtx, MTX_DEF); + mtx_unlock(&all_mtx); /* Mark the witness code as being ready for use. */ atomic_store_rel_int(&witness_cold, 0); - mtx_enter(&Giant, MTX_DEF); + mtx_lock(&Giant); } SYSINIT(wtnsfxup, SI_SUB_MUTEX, SI_ORDER_FIRST, witness_fixup, NULL) @@ -1061,6 +911,9 @@ TUNABLE_INT_DECL("debug.witness_skipspin", 0, witness_skipspin); SYSCTL_INT(_debug, OID_AUTO, witness_skipspin, CTLFLAG_RD, &witness_skipspin, 0, ""); +/* + * Witness-enabled globals + */ static struct mtx w_mtx; static struct witness *w_free; static struct witness *w_all; @@ -1069,20 +922,22 @@ static int witness_dead; /* fatal error, probably no memory */ static struct witness w_data[WITNESS_COUNT]; -static struct witness *enroll __P((const char *description, int flag)); -static int itismychild __P((struct witness *parent, struct witness *child)); -static void removechild __P((struct witness *parent, struct witness *child)); -static int isitmychild __P((struct witness *parent, struct witness *child)); -static int isitmydescendant __P((struct witness *parent, struct witness *child)); -static int dup_ok __P((struct witness *)); -static int blessed __P((struct witness *, struct witness *)); -static void witness_displaydescendants - __P((void(*)(const char *fmt, ...), struct witness *)); -static void witness_leveldescendents __P((struct witness *parent, int level)); -static void witness_levelall __P((void)); -static struct witness * witness_get __P((void)); -static void witness_free __P((struct witness *m)); - +/* + * Internal witness routine prototypes + */ +static struct witness *enroll(const char *description, int flag); +static int itismychild(struct witness *parent, struct witness *child); +static void removechild(struct witness *parent, struct witness *child); +static int isitmychild(struct witness *parent, struct witness *child); +static int isitmydescendant(struct witness *parent, struct witness *child); +static int dup_ok(struct witness *); +static int blessed(struct witness *, struct witness *); +static void + witness_displaydescendants(void(*)(const char *fmt, ...), struct witness *); +static void witness_leveldescendents(struct witness *parent, int level); +static void witness_levelall(void); +static struct witness * witness_get(void); +static void witness_free(struct witness *m); static char *ignore_list[] = { "witness lock", @@ -1129,7 +984,8 @@ static char *sleep_list[] = { */ static struct witness_blessed blessed_list[] = { }; -static int blessed_count = sizeof(blessed_list) / sizeof(struct witness_blessed); +static int blessed_count = + sizeof(blessed_list) / sizeof(struct witness_blessed); static void witness_init(struct mtx *m, int flag) @@ -1211,17 +1067,17 @@ witness_enter(struct mtx *m, int flags, const char *file, int line) file, line); return; } - mtx_enter(&w_mtx, MTX_SPIN | MTX_QUIET); + mtx_lock_spin_flags(&w_mtx, MTX_QUIET); i = PCPU_GET(witness_spin_check); if (i != 0 && w->w_level < i) { - mtx_exit(&w_mtx, MTX_SPIN | MTX_QUIET); + mtx_unlock_spin_flags(&w_mtx, MTX_QUIET); panic("mutex_enter(%s:%x, MTX_SPIN) out of order @" " %s:%d already holding %s:%x", m->mtx_description, w->w_level, file, line, spin_order_list[ffs(i)-1], i); } PCPU_SET(witness_spin_check, i | w->w_level); - mtx_exit(&w_mtx, MTX_SPIN | MTX_QUIET); + mtx_unlock_spin_flags(&w_mtx, MTX_QUIET); w->w_file = file; w->w_line = line; m->mtx_line = line; @@ -1245,7 +1101,7 @@ witness_enter(struct mtx *m, int flags, const char *file, int line) goto out; if (!mtx_legal2block()) - panic("blockable mtx_enter() of %s when not legal @ %s:%d", + panic("blockable mtx_lock() of %s when not legal @ %s:%d", m->mtx_description, file, line); /* * Is this the first mutex acquired @@ -1267,16 +1123,16 @@ witness_enter(struct mtx *m, int flags, const char *file, int line) goto out; } MPASS(!mtx_owned(&w_mtx)); - mtx_enter(&w_mtx, MTX_SPIN | MTX_QUIET); + mtx_lock_spin_flags(&w_mtx, MTX_QUIET); /* * If we have a known higher number just say ok */ if (witness_watch > 1 && w->w_level > w1->w_level) { - mtx_exit(&w_mtx, MTX_SPIN | MTX_QUIET); + mtx_unlock_spin_flags(&w_mtx, MTX_QUIET); goto out; } if (isitmydescendant(m1->mtx_witness, w)) { - mtx_exit(&w_mtx, MTX_SPIN | MTX_QUIET); + mtx_unlock_spin_flags(&w_mtx, MTX_QUIET); goto out; } for (i = 0; m1 != NULL; m1 = LIST_NEXT(m1, mtx_held), i++) { @@ -1284,7 +1140,7 @@ witness_enter(struct mtx *m, int flags, const char *file, int line) MPASS(i < 200); w1 = m1->mtx_witness; if (isitmydescendant(w, w1)) { - mtx_exit(&w_mtx, MTX_SPIN | MTX_QUIET); + mtx_unlock_spin_flags(&w_mtx, MTX_QUIET); if (blessed(w, w1)) goto out; if (m1 == &Giant) { @@ -1313,7 +1169,7 @@ witness_enter(struct mtx *m, int flags, const char *file, int line) } m1 = LIST_FIRST(&p->p_heldmtx); if (!itismychild(m1->mtx_witness, w)) - mtx_exit(&w_mtx, MTX_SPIN | MTX_QUIET); + mtx_unlock_spin_flags(&w_mtx, MTX_QUIET); out: #ifdef DDB @@ -1356,10 +1212,10 @@ witness_try_enter(struct mtx *m, int flags, const char *file, int line) m->mtx_description, file, line); return; } - mtx_enter(&w_mtx, MTX_SPIN | MTX_QUIET); + mtx_lock_spin_flags(&w_mtx, MTX_QUIET); PCPU_SET(witness_spin_check, PCPU_GET(witness_spin_check) | w->w_level); - mtx_exit(&w_mtx, MTX_SPIN | MTX_QUIET); + mtx_unlock_spin_flags(&w_mtx, MTX_QUIET); w->w_file = file; w->w_line = line; m->mtx_line = line; @@ -1407,10 +1263,10 @@ witness_exit(struct mtx *m, int flags, const char *file, int line) file, line); return; } - mtx_enter(&w_mtx, MTX_SPIN | MTX_QUIET); + mtx_lock_spin_flags(&w_mtx, MTX_QUIET); PCPU_SET(witness_spin_check, PCPU_GET(witness_spin_check) & ~w->w_level); - mtx_exit(&w_mtx, MTX_SPIN | MTX_QUIET); + mtx_unlock_spin_flags(&w_mtx, MTX_QUIET); return; } if ((m->mtx_flags & MTX_SPIN) != 0) @@ -1426,7 +1282,7 @@ witness_exit(struct mtx *m, int flags, const char *file, int line) } if ((flags & MTX_NOSWITCH) == 0 && !mtx_legal2block() && !cold) - panic("switchable mtx_exit() of %s when not legal @ %s:%d", + panic("switchable mtx_unlock() of %s when not legal @ %s:%d", m->mtx_description, file, line); LIST_REMOVE(m, mtx_held); m->mtx_held.le_prev = NULL; @@ -1497,10 +1353,10 @@ enroll(const char *description, int flag) } if ((flag & MTX_SPIN) && witness_skipspin) return (NULL); - mtx_enter(&w_mtx, MTX_SPIN | MTX_QUIET); + mtx_lock_spin_flags(&w_mtx, MTX_QUIET); for (w = w_all; w; w = w->w_next) { if (strcmp(description, w->w_description) == 0) { - mtx_exit(&w_mtx, MTX_SPIN | MTX_QUIET); + mtx_unlock_spin_flags(&w_mtx, MTX_QUIET); return (w); } } @@ -1509,7 +1365,7 @@ enroll(const char *description, int flag) w->w_next = w_all; w_all = w; w->w_description = description; - mtx_exit(&w_mtx, MTX_SPIN | MTX_QUIET); + mtx_unlock_spin_flags(&w_mtx, MTX_QUIET); if (flag & MTX_SPIN) { w->w_spin = 1; @@ -1731,7 +1587,7 @@ witness_get() if ((w = w_free) == NULL) { witness_dead = 1; - mtx_exit(&w_mtx, MTX_SPIN | MTX_QUIET); + mtx_unlock_spin_flags(&w_mtx, MTX_QUIET); printf("witness exhausted\n"); return (NULL); } |
