[rtems-libbsd commit] SLEEP(9): Import from FreeBSD
Sebastian Huber
sebh at rtems.org
Tue Mar 24 14:28:56 UTC 2015
Module: rtems-libbsd
Branch: master
Commit: f661c797324df9783fa7f747c06bc674176d2940
Changeset: http://git.rtems.org/rtems-libbsd/commit/?id=f661c797324df9783fa7f747c06bc674176d2940
Author: Sebastian Huber <sebastian.huber at embedded-brains.de>
Date: Tue Mar 24 10:08:40 2015 +0100
SLEEP(9): Import from FreeBSD
---
freebsd/sys/kern/kern_synch.c | 625 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 625 insertions(+)
diff --git a/freebsd/sys/kern/kern_synch.c b/freebsd/sys/kern/kern_synch.c
new file mode 100644
index 0000000..6ee1209
--- /dev/null
+++ b/freebsd/sys/kern/kern_synch.c
@@ -0,0 +1,625 @@
+#include <machine/rtems-bsd-kernel-space.h>
+
+/*-
+ * Copyright (c) 1982, 1986, 1990, 1991, 1993
+ * The Regents of the University of California. All rights reserved.
+ * (c) UNIX System Laboratories, Inc.
+ * All or some portions of this file are derived from material licensed
+ * to the University of California by American Telephone and Telegraph
+ * Co. or Unix System Laboratories, Inc. and are reproduced herein with
+ * the permission of UNIX System Laboratories, Inc.
+ *
+ * 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.
+ * 4. 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_synch.c 8.9 (Berkeley) 5/19/95
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <rtems/bsd/local/opt_kdtrace.h>
+#include <rtems/bsd/local/opt_ktrace.h>
+#include <rtems/bsd/local/opt_sched.h>
+
+#include <rtems/bsd/sys/param.h>
+#include <sys/systm.h>
+#include <sys/condvar.h>
+#include <sys/kdb.h>
+#include <sys/kernel.h>
+#include <sys/ktr.h>
+#include <rtems/bsd/sys/lock.h>
+#include <sys/mutex.h>
+#include <sys/proc.h>
+#include <sys/resourcevar.h>
+#include <sys/sched.h>
+#include <sys/sdt.h>
+#include <sys/signalvar.h>
+#include <sys/sleepqueue.h>
+#include <sys/smp.h>
+#include <sys/sx.h>
+#include <sys/sysctl.h>
+#include <sys/sysproto.h>
+#include <sys/vmmeter.h>
+#ifdef KTRACE
+#include <sys/uio.h>
+#include <sys/ktrace.h>
+#endif
+
+#include <machine/cpu.h>
+
+#ifdef XEN
+#include <vm/vm.h>
+#include <vm/vm_param.h>
+#include <vm/pmap.h>
+#endif
+
+#define KTDSTATE(td) \
+ (((td)->td_inhibitors & TDI_SLEEPING) != 0 ? "sleep" : \
+ ((td)->td_inhibitors & TDI_SUSPENDED) != 0 ? "suspended" : \
+ ((td)->td_inhibitors & TDI_SWAPPED) != 0 ? "swapped" : \
+ ((td)->td_inhibitors & TDI_LOCK) != 0 ? "blocked" : \
+ ((td)->td_inhibitors & TDI_IWAIT) != 0 ? "iwait" : "yielding")
+
+static void synch_setup(void *dummy);
+SYSINIT(synch_setup, SI_SUB_KICK_SCHEDULER, SI_ORDER_FIRST, synch_setup,
+ NULL);
+
+int hogticks;
+static int pause_wchan;
+
+static struct callout loadav_callout;
+
+struct loadavg averunnable =
+ { {0, 0, 0}, FSCALE }; /* load average, of runnable procs */
+/*
+ * Constants for averages over 1, 5, and 15 minutes
+ * when sampling at 5 second intervals.
+ */
+static fixpt_t cexp[3] = {
+ 0.9200444146293232 * FSCALE, /* exp(-1/12) */
+ 0.9834714538216174 * FSCALE, /* exp(-1/60) */
+ 0.9944598480048967 * FSCALE, /* exp(-1/180) */
+};
+
+/* kernel uses `FSCALE', userland (SHOULD) use kern.fscale */
+static int fscale __unused = FSCALE;
+SYSCTL_INT(_kern, OID_AUTO, fscale, CTLFLAG_RD, 0, FSCALE, "");
+
+static void loadav(void *arg);
+
+SDT_PROVIDER_DECLARE(sched);
+SDT_PROBE_DEFINE(sched, , , preempt);
+
+/*
+ * These probes reference Solaris features that are not implemented in FreeBSD.
+ * Create the probes anyway for compatibility with existing D scripts; they'll
+ * just never fire.
+ */
+SDT_PROBE_DEFINE(sched, , , cpucaps__sleep);
+SDT_PROBE_DEFINE(sched, , , cpucaps__wakeup);
+SDT_PROBE_DEFINE(sched, , , schedctl__nopreempt);
+SDT_PROBE_DEFINE(sched, , , schedctl__preempt);
+SDT_PROBE_DEFINE(sched, , , schedctl__yield);
+
+void
+sleepinit(void)
+{
+
+ hogticks = (hz / 10) * 2; /* Default only. */
+ init_sleepqueues();
+}
+
+/*
+ * General sleep call. Suspends the current thread until a wakeup is
+ * performed on the specified identifier. The thread will then be made
+ * runnable with the specified priority. Sleeps at most timo/hz seconds
+ * (0 means no timeout). If pri includes PCATCH flag, signals are checked
+ * before and after sleeping, else signals are not checked. Returns 0 if
+ * awakened, EWOULDBLOCK if the timeout expires. If PCATCH is set and a
+ * signal needs to be delivered, ERESTART is returned if the current system
+ * call should be restarted if possible, and EINTR is returned if the system
+ * call should be interrupted by the signal (return EINTR).
+ *
+ * The lock argument is unlocked before the caller is suspended, and
+ * re-locked before _sleep() returns. If priority includes the PDROP
+ * flag the lock is not re-locked before returning.
+ */
+int
+_sleep(void *ident, struct lock_object *lock, int priority,
+ const char *wmesg, int timo)
+{
+ struct thread *td;
+ struct proc *p;
+ struct lock_class *class;
+ int catch, flags, lock_state, pri, rval;
+ WITNESS_SAVE_DECL(lock_witness);
+
+ td = curthread;
+ p = td->td_proc;
+#ifdef KTRACE
+ if (KTRPOINT(td, KTR_CSW))
+ ktrcsw(1, 0, wmesg);
+#endif
+ WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
+ "Sleeping on \"%s\"", wmesg);
+ KASSERT(timo != 0 || mtx_owned(&Giant) || lock != NULL,
+ ("sleeping without a lock"));
+ KASSERT(p != NULL, ("msleep1"));
+ KASSERT(ident != NULL && TD_IS_RUNNING(td), ("msleep"));
+ if (priority & PDROP)
+ KASSERT(lock != NULL && lock != &Giant.lock_object,
+ ("PDROP requires a non-Giant lock"));
+ if (lock != NULL)
+ class = LOCK_CLASS(lock);
+ else
+ class = NULL;
+
+ if (cold || SCHEDULER_STOPPED()) {
+ /*
+ * During autoconfiguration, just return;
+ * don't run any other threads or panic below,
+ * in case this is the idle thread and already asleep.
+ * XXX: this used to do "s = splhigh(); splx(safepri);
+ * splx(s);" to give interrupts a chance, but there is
+ * no way to give interrupts a chance now.
+ */
+ if (lock != NULL && priority & PDROP)
+ class->lc_unlock(lock);
+ return (0);
+ }
+ catch = priority & PCATCH;
+ pri = priority & PRIMASK;
+
+ /*
+ * If we are already on a sleep queue, then remove us from that
+ * sleep queue first. We have to do this to handle recursive
+ * sleeps.
+ */
+ if (TD_ON_SLEEPQ(td))
+ sleepq_remove(td, td->td_wchan);
+
+ if (ident == &pause_wchan)
+ flags = SLEEPQ_PAUSE;
+ else
+ flags = SLEEPQ_SLEEP;
+ if (catch)
+ flags |= SLEEPQ_INTERRUPTIBLE;
+ if (priority & PBDRY)
+ flags |= SLEEPQ_STOP_ON_BDRY;
+
+ sleepq_lock(ident);
+ CTR5(KTR_PROC, "sleep: thread %ld (pid %ld, %s) on %s (%p)",
+ td->td_tid, p->p_pid, td->td_name, wmesg, ident);
+
+ if (lock == &Giant.lock_object)
+ mtx_assert(&Giant, MA_OWNED);
+ DROP_GIANT();
+ if (lock != NULL && lock != &Giant.lock_object &&
+ !(class->lc_flags & LC_SLEEPABLE)) {
+ WITNESS_SAVE(lock, lock_witness);
+ lock_state = class->lc_unlock(lock);
+ } else
+ /* GCC needs to follow the Yellow Brick Road */
+ lock_state = -1;
+
+ /*
+ * We put ourselves on the sleep queue and start our timeout
+ * before calling thread_suspend_check, as we could stop there,
+ * and a wakeup or a SIGCONT (or both) could occur while we were
+ * stopped without resuming us. Thus, we must be ready for sleep
+ * when cursig() is called. If the wakeup happens while we're
+ * stopped, then td will no longer be on a sleep queue upon
+ * return from cursig().
+ */
+ sleepq_add(ident, lock, wmesg, flags, 0);
+ if (timo)
+ sleepq_set_timeout(ident, timo);
+ if (lock != NULL && class->lc_flags & LC_SLEEPABLE) {
+ sleepq_release(ident);
+ WITNESS_SAVE(lock, lock_witness);
+ lock_state = class->lc_unlock(lock);
+ sleepq_lock(ident);
+ }
+ if (timo && catch)
+ rval = sleepq_timedwait_sig(ident, pri);
+ else if (timo)
+ rval = sleepq_timedwait(ident, pri);
+ else if (catch)
+ rval = sleepq_wait_sig(ident, pri);
+ else {
+ sleepq_wait(ident, pri);
+ rval = 0;
+ }
+#ifdef KTRACE
+ if (KTRPOINT(td, KTR_CSW))
+ ktrcsw(0, 0, wmesg);
+#endif
+ PICKUP_GIANT();
+ if (lock != NULL && lock != &Giant.lock_object && !(priority & PDROP)) {
+ class->lc_lock(lock, lock_state);
+ WITNESS_RESTORE(lock, lock_witness);
+ }
+ return (rval);
+}
+
+int
+msleep_spin(void *ident, struct mtx *mtx, const char *wmesg, int timo)
+{
+ struct thread *td;
+ struct proc *p;
+ int rval;
+ WITNESS_SAVE_DECL(mtx);
+
+ td = curthread;
+ p = td->td_proc;
+ KASSERT(mtx != NULL, ("sleeping without a mutex"));
+ KASSERT(p != NULL, ("msleep1"));
+ KASSERT(ident != NULL && TD_IS_RUNNING(td), ("msleep"));
+
+ if (cold || SCHEDULER_STOPPED()) {
+ /*
+ * During autoconfiguration, just return;
+ * don't run any other threads or panic below,
+ * in case this is the idle thread and already asleep.
+ * XXX: this used to do "s = splhigh(); splx(safepri);
+ * splx(s);" to give interrupts a chance, but there is
+ * no way to give interrupts a chance now.
+ */
+ return (0);
+ }
+
+ sleepq_lock(ident);
+ CTR5(KTR_PROC, "msleep_spin: thread %ld (pid %ld, %s) on %s (%p)",
+ td->td_tid, p->p_pid, td->td_name, wmesg, ident);
+
+ DROP_GIANT();
+ mtx_assert(mtx, MA_OWNED | MA_NOTRECURSED);
+ WITNESS_SAVE(&mtx->lock_object, mtx);
+ mtx_unlock_spin(mtx);
+
+ /*
+ * We put ourselves on the sleep queue and start our timeout.
+ */
+ sleepq_add(ident, &mtx->lock_object, wmesg, SLEEPQ_SLEEP, 0);
+ if (timo)
+ sleepq_set_timeout(ident, timo);
+
+ /*
+ * Can't call ktrace with any spin locks held so it can lock the
+ * ktrace_mtx lock, and WITNESS_WARN considers it an error to hold
+ * any spin lock. Thus, we have to drop the sleepq spin lock while
+ * we handle those requests. This is safe since we have placed our
+ * thread on the sleep queue already.
+ */
+#ifdef KTRACE
+ if (KTRPOINT(td, KTR_CSW)) {
+ sleepq_release(ident);
+ ktrcsw(1, 0, wmesg);
+ sleepq_lock(ident);
+ }
+#endif
+#ifdef WITNESS
+ sleepq_release(ident);
+ WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, "Sleeping on \"%s\"",
+ wmesg);
+ sleepq_lock(ident);
+#endif
+ if (timo)
+ rval = sleepq_timedwait(ident, 0);
+ else {
+ sleepq_wait(ident, 0);
+ rval = 0;
+ }
+#ifdef KTRACE
+ if (KTRPOINT(td, KTR_CSW))
+ ktrcsw(0, 0, wmesg);
+#endif
+ PICKUP_GIANT();
+ mtx_lock_spin(mtx);
+ WITNESS_RESTORE(&mtx->lock_object, mtx);
+ return (rval);
+}
+
+/*
+ * pause() delays the calling thread by the given number of system ticks.
+ * During cold bootup, pause() uses the DELAY() function instead of
+ * the tsleep() function to do the waiting. The "timo" argument must be
+ * greater than or equal to zero. A "timo" value of zero is equivalent
+ * to a "timo" value of one.
+ */
+int
+pause(const char *wmesg, int timo)
+{
+ KASSERT(timo >= 0, ("pause: timo must be >= 0"));
+
+ /* silently convert invalid timeouts */
+ if (timo < 1)
+ timo = 1;
+
+ if (cold) {
+ /*
+ * We delay one HZ at a time to avoid overflowing the
+ * system specific DELAY() function(s):
+ */
+ while (timo >= hz) {
+ DELAY(1000000);
+ timo -= hz;
+ }
+ if (timo > 0)
+ DELAY(timo * tick);
+ return (0);
+ }
+ return (tsleep(&pause_wchan, 0, wmesg, timo));
+}
+
+/*
+ * Make all threads sleeping on the specified identifier runnable.
+ */
+void
+wakeup(void *ident)
+{
+ int wakeup_swapper;
+
+ sleepq_lock(ident);
+ wakeup_swapper = sleepq_broadcast(ident, SLEEPQ_SLEEP, 0, 0);
+ sleepq_release(ident);
+ if (wakeup_swapper) {
+ KASSERT(ident != &proc0,
+ ("wakeup and wakeup_swapper and proc0"));
+ kick_proc0();
+ }
+}
+
+/*
+ * Make a thread sleeping on the specified identifier runnable.
+ * May wake more than one thread if a target thread is currently
+ * swapped out.
+ */
+void
+wakeup_one(void *ident)
+{
+ int wakeup_swapper;
+
+ sleepq_lock(ident);
+ wakeup_swapper = sleepq_signal(ident, SLEEPQ_SLEEP, 0, 0);
+ sleepq_release(ident);
+ if (wakeup_swapper)
+ kick_proc0();
+}
+
+static void
+kdb_switch(void)
+{
+ thread_unlock(curthread);
+ kdb_backtrace();
+ kdb_reenter();
+ panic("%s: did not reenter debugger", __func__);
+}
+
+/*
+ * The machine independent parts of context switching.
+ */
+void
+mi_switch(int flags, struct thread *newtd)
+{
+ uint64_t runtime, new_switchtime;
+ struct thread *td;
+ struct proc *p;
+
+ td = curthread; /* XXX */
+ THREAD_LOCK_ASSERT(td, MA_OWNED | MA_NOTRECURSED);
+ p = td->td_proc; /* XXX */
+ KASSERT(!TD_ON_RUNQ(td), ("mi_switch: called by old code"));
+#ifdef INVARIANTS
+ if (!TD_ON_LOCK(td) && !TD_IS_RUNNING(td))
+ mtx_assert(&Giant, MA_NOTOWNED);
+#endif
+ KASSERT(td->td_critnest == 1 || panicstr,
+ ("mi_switch: switch in a critical section"));
+ KASSERT((flags & (SW_INVOL | SW_VOL)) != 0,
+ ("mi_switch: switch must be voluntary or involuntary"));
+ KASSERT(newtd != curthread, ("mi_switch: preempting back to ourself"));
+
+ /*
+ * Don't perform context switches from the debugger.
+ */
+ if (kdb_active)
+ kdb_switch();
+ if (SCHEDULER_STOPPED())
+ return;
+ if (flags & SW_VOL) {
+ td->td_ru.ru_nvcsw++;
+ td->td_swvoltick = ticks;
+ } else
+ td->td_ru.ru_nivcsw++;
+#ifdef SCHED_STATS
+ SCHED_STAT_INC(sched_switch_stats[flags & SW_TYPE_MASK]);
+#endif
+ /*
+ * Compute the amount of time during which the current
+ * thread was running, and add that to its total so far.
+ */
+ new_switchtime = cpu_ticks();
+ runtime = new_switchtime - PCPU_GET(switchtime);
+ td->td_runtime += runtime;
+ td->td_incruntime += runtime;
+ PCPU_SET(switchtime, new_switchtime);
+ td->td_generation++; /* bump preempt-detect counter */
+ PCPU_INC(cnt.v_swtch);
+ PCPU_SET(switchticks, ticks);
+ CTR4(KTR_PROC, "mi_switch: old thread %ld (td_sched %p, pid %ld, %s)",
+ td->td_tid, td->td_sched, p->p_pid, td->td_name);
+#if (KTR_COMPILE & KTR_SCHED) != 0
+ if (TD_IS_IDLETHREAD(td))
+ KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "idle",
+ "prio:%d", td->td_priority);
+ else
+ KTR_STATE3(KTR_SCHED, "thread", sched_tdname(td), KTDSTATE(td),
+ "prio:%d", td->td_priority, "wmesg:\"%s\"", td->td_wmesg,
+ "lockname:\"%s\"", td->td_lockname);
+#endif
+ SDT_PROBE0(sched, , , preempt);
+#ifdef XEN
+ PT_UPDATES_FLUSH();
+#endif
+ sched_switch(td, newtd, flags);
+ KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "running",
+ "prio:%d", td->td_priority);
+
+ CTR4(KTR_PROC, "mi_switch: new thread %ld (td_sched %p, pid %ld, %s)",
+ td->td_tid, td->td_sched, p->p_pid, td->td_name);
+
+ /*
+ * If the last thread was exiting, finish cleaning it up.
+ */
+ if ((td = PCPU_GET(deadthread))) {
+ PCPU_SET(deadthread, NULL);
+ thread_stash(td);
+ }
+}
+
+/*
+ * Change thread state to be runnable, placing it on the run queue if
+ * it is in memory. If it is swapped out, return true so our caller
+ * will know to awaken the swapper.
+ */
+int
+setrunnable(struct thread *td)
+{
+
+ THREAD_LOCK_ASSERT(td, MA_OWNED);
+ KASSERT(td->td_proc->p_state != PRS_ZOMBIE,
+ ("setrunnable: pid %d is a zombie", td->td_proc->p_pid));
+ switch (td->td_state) {
+ case TDS_RUNNING:
+ case TDS_RUNQ:
+ return (0);
+ case TDS_INHIBITED:
+ /*
+ * If we are only inhibited because we are swapped out
+ * then arange to swap in this process. Otherwise just return.
+ */
+ if (td->td_inhibitors != TDI_SWAPPED)
+ return (0);
+ /* FALLTHROUGH */
+ case TDS_CAN_RUN:
+ break;
+ default:
+ printf("state is 0x%x", td->td_state);
+ panic("setrunnable(2)");
+ }
+ if ((td->td_flags & TDF_INMEM) == 0) {
+ if ((td->td_flags & TDF_SWAPINREQ) == 0) {
+ td->td_flags |= TDF_SWAPINREQ;
+ return (1);
+ }
+ } else
+ sched_wakeup(td);
+ return (0);
+}
+
+/*
+ * Compute a tenex style load average of a quantity on
+ * 1, 5 and 15 minute intervals.
+ */
+static void
+loadav(void *arg)
+{
+ int i, nrun;
+ struct loadavg *avg;
+
+ nrun = sched_load();
+ avg = &averunnable;
+
+ for (i = 0; i < 3; i++)
+ avg->ldavg[i] = (cexp[i] * avg->ldavg[i] +
+ nrun * FSCALE * (FSCALE - cexp[i])) >> FSHIFT;
+
+ /*
+ * Schedule the next update to occur after 5 seconds, but add a
+ * random variation to avoid synchronisation with processes that
+ * run at regular intervals.
+ */
+ callout_reset(&loadav_callout, hz * 4 + (int)(random() % (hz * 2 + 1)),
+ loadav, NULL);
+}
+
+/* ARGSUSED */
+static void
+synch_setup(void *dummy)
+{
+ callout_init(&loadav_callout, CALLOUT_MPSAFE);
+
+ /* Kick off timeout driven events by calling first time. */
+ loadav(NULL);
+}
+
+int
+should_yield(void)
+{
+
+ return ((u_int)ticks - (u_int)curthread->td_swvoltick >= hogticks);
+}
+
+void
+maybe_yield(void)
+{
+
+ if (should_yield())
+ kern_yield(PRI_USER);
+}
+
+void
+kern_yield(int prio)
+{
+ struct thread *td;
+
+ td = curthread;
+ DROP_GIANT();
+ thread_lock(td);
+ if (prio == PRI_USER)
+ prio = td->td_user_pri;
+ if (prio >= 0)
+ sched_prio(td, prio);
+ mi_switch(SW_VOL | SWT_RELINQUISH, NULL);
+ thread_unlock(td);
+ PICKUP_GIANT();
+}
+
+/*
+ * General purpose yield system call.
+ */
+int
+sys_yield(struct thread *td, struct yield_args *uap)
+{
+
+ thread_lock(td);
+ if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE)
+ sched_prio(td, PRI_MAX_TIMESHARE);
+ mi_switch(SW_VOL | SWT_RELINQUISH, NULL);
+ thread_unlock(td);
+ td->td_retval[0] = 0;
+ return (0);
+}
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