/* * Copyright (c) 2005 The DragonFly Project. All rights reserved. * * This code is derived from software contributed to The DragonFly Project * by Matthew Dillon * * 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 DragonFly Project 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 COPYRIGHT HOLDERS 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 * COPYRIGHT HOLDERS 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. */ /* * This API provides a fast locked-bus-cycle-based serializer. It's * basically a low level NON-RECURSIVE exclusive lock that can be held across * a blocking condition. It is NOT a mutex. * * This serializer is primarily designed for low level situations and * interrupt/device interaction. There are two primary facilities. First, * the serializer facility itself. Second, an integrated interrupt handler * disablement facility. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifndef SLZ_ADAPTIVE_SPINMAX #define SLZ_ADAPTIVE_SPINMAX 4096 #endif #define SLZ_KTR_STRING "slz=%p" #define SLZ_KTR_ARGS lwkt_serialize_t slz #ifndef KTR_SERIALIZER #define KTR_SERIALIZER KTR_ALL #endif KTR_INFO_MASTER(slz); KTR_INFO(KTR_SERIALIZER, slz, enter_beg, 0, SLZ_KTR_STRING, SLZ_KTR_ARGS); KTR_INFO(KTR_SERIALIZER, slz, sleep_beg, 1, SLZ_KTR_STRING, SLZ_KTR_ARGS); KTR_INFO(KTR_SERIALIZER, slz, sleep_end, 2, SLZ_KTR_STRING, SLZ_KTR_ARGS); KTR_INFO(KTR_SERIALIZER, slz, exit_end, 3, SLZ_KTR_STRING, SLZ_KTR_ARGS); KTR_INFO(KTR_SERIALIZER, slz, wakeup_beg, 4, SLZ_KTR_STRING, SLZ_KTR_ARGS); KTR_INFO(KTR_SERIALIZER, slz, wakeup_end, 5, SLZ_KTR_STRING, SLZ_KTR_ARGS); KTR_INFO(KTR_SERIALIZER, slz, try, 6, SLZ_KTR_STRING, SLZ_KTR_ARGS); KTR_INFO(KTR_SERIALIZER, slz, tryfail, 7, SLZ_KTR_STRING, SLZ_KTR_ARGS); KTR_INFO(KTR_SERIALIZER, slz, tryok, 8, SLZ_KTR_STRING, SLZ_KTR_ARGS); KTR_INFO(KTR_SERIALIZER, slz, enter_end, 9, SLZ_KTR_STRING, SLZ_KTR_ARGS); KTR_INFO(KTR_SERIALIZER, slz, exit_beg, 10, SLZ_KTR_STRING, SLZ_KTR_ARGS); KTR_INFO(KTR_SERIALIZER, slz, adapt_beg, 11, SLZ_KTR_STRING, SLZ_KTR_ARGS); KTR_INFO(KTR_SERIALIZER, slz, adapt_end, 12, SLZ_KTR_STRING, SLZ_KTR_ARGS); KTR_INFO(KTR_SERIALIZER, slz, adapt_spinend, 13, "slz=%p try=%d", lwkt_serialize_t slz, int try); KTR_INFO(KTR_SERIALIZER, slz, adapt_sleepb, 14, SLZ_KTR_STRING, SLZ_KTR_ARGS); KTR_INFO(KTR_SERIALIZER, slz, adapt_sleepe, 15, SLZ_KTR_STRING, SLZ_KTR_ARGS); #define logslz(name, slz) KTR_LOG(slz_ ## name, slz) #define logslz_spinend(slz, try) KTR_LOG(slz_adapt_spinend, slz, try) static void lwkt_serialize_sleep(void *info); static void lwkt_serialize_wakeup(void *info); void lwkt_serialize_init(lwkt_serialize_t s) { atomic_intr_init(&s->interlock); s->last_td = (void *)-4; } void lwkt_serialize_enter(lwkt_serialize_t s) { ASSERT_NOT_SERIALIZED(s); logslz(enter_beg, s); atomic_intr_cond_enter(&s->interlock, lwkt_serialize_sleep, s); logslz(enter_end, s); s->last_td = curthread; } /* * Returns non-zero on success */ int lwkt_serialize_try(lwkt_serialize_t s) { int error; ASSERT_NOT_SERIALIZED(s); logslz(try, s); if ((error = atomic_intr_cond_try(&s->interlock)) == 0) { s->last_td = curthread; logslz(tryok, s); return(1); } logslz(tryfail, s); return (0); } void lwkt_serialize_exit(lwkt_serialize_t s) { ASSERT_SERIALIZED(s); s->last_td = (void *)-2; logslz(exit_beg, s); atomic_intr_cond_exit(&s->interlock, lwkt_serialize_wakeup, s); logslz(exit_end, s); } /* * Interrupt handler disablement support, used by drivers. Non-stackable * (uses bit 30). */ void lwkt_serialize_handler_disable(lwkt_serialize_t s) { atomic_intr_handler_disable(&s->interlock); } void lwkt_serialize_handler_enable(lwkt_serialize_t s) { atomic_intr_handler_enable(&s->interlock); } void lwkt_serialize_handler_call(lwkt_serialize_t s, void (*func)(void *, void *), void *arg, void *frame) { /* * note: a return value of 0 indicates that the interrupt handler is * enabled. */ if (atomic_intr_handler_is_enabled(&s->interlock) == 0) { logslz(enter_beg, s); atomic_intr_cond_enter(&s->interlock, lwkt_serialize_sleep, s); logslz(enter_end, s); s->last_td = curthread; if (atomic_intr_handler_is_enabled(&s->interlock) == 0) func(arg, frame); ASSERT_SERIALIZED(s); s->last_td = (void *)-2; logslz(exit_beg, s); atomic_intr_cond_exit(&s->interlock, lwkt_serialize_wakeup, s); logslz(exit_end, s); } } /* * Similar to handler_call but does not block. Returns 0 on success, * and 1 on failure. */ int lwkt_serialize_handler_try(lwkt_serialize_t s, void (*func)(void *, void *), void *arg, void *frame) { /* * note: a return value of 0 indicates that the interrupt handler is * enabled. */ if (atomic_intr_handler_is_enabled(&s->interlock) == 0) { logslz(try, s); if (atomic_intr_cond_try(&s->interlock) == 0) { s->last_td = curthread; logslz(tryok, s); func(arg, frame); ASSERT_SERIALIZED(s); s->last_td = (void *)-2; logslz(exit_beg, s); atomic_intr_cond_exit(&s->interlock, lwkt_serialize_wakeup, s); logslz(exit_end, s); return(0); } } logslz(tryfail, s); return(1); } /* * Helper functions * * It is possible to race an interrupt which acquires and releases the * bit, then calls wakeup before we actually go to sleep, so we * need to check that the interlock is still acquired from within * a critical section prior to sleeping. */ static void lwkt_serialize_sleep(void *info) { lwkt_serialize_t s = info; tsleep_interlock(s, 0); if (atomic_intr_cond_test(&s->interlock) != 0) { logslz(sleep_beg, s); tsleep(s, PINTERLOCKED, "slize", 0); logslz(sleep_end, s); } } void lwkt_serialize_adaptive_enter(lwkt_serialize_t s) { int try; ASSERT_NOT_SERIALIZED(s); logslz(adapt_beg, s); if (atomic_intr_cond_try(&s->interlock) == 0) { s->last_td = curthread; logslz(adapt_end, s); return; } restart: /* * Spinning a little bit, before going to sleep * * See the comment before kern/kern_spinlock.c * _spin_lock_contested() about why atomic_intr_cond_test() * is called first. atomic_intr_cond_test() contains * _no_ MPLOCKED intruction. */ for (try = SLZ_ADAPTIVE_SPINMAX; try; --try) { if (atomic_intr_cond_test(&s->interlock) == 0 && atomic_intr_cond_try(&s->interlock) == 0) { s->last_td = curthread; logslz_spinend(s, try); return; } } atomic_intr_cond_inc(&s->interlock); tsleep_interlock(s, 0); if (atomic_intr_cond_try(&s->interlock) == 0) { atomic_intr_cond_dec(&s->interlock); s->last_td = curthread; logslz_spinend(s, 0); return; } else { logslz(adapt_sleepb, s); tsleep(s, PINTERLOCKED, "aslize", 0); logslz(adapt_sleepe, s); atomic_intr_cond_dec(&s->interlock); goto restart; } } static void lwkt_serialize_wakeup(void *info) { logslz(wakeup_beg, info); wakeup(info); logslz(wakeup_end, info); }