diff options
Diffstat (limited to 'sys/kern/kern_thread.c')
| -rw-r--r-- | sys/kern/kern_thread.c | 1054 |
1 files changed, 1054 insertions, 0 deletions
diff --git a/sys/kern/kern_thread.c b/sys/kern/kern_thread.c new file mode 100644 index 0000000..5da4866 --- /dev/null +++ b/sys/kern/kern_thread.c @@ -0,0 +1,1054 @@ +/*- + * Copyright (C) 2001 Julian Elischer <julian@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_witness.h" +#include "opt_kdtrace.h" +#include "opt_hwpmc_hooks.h" + +#include <sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +#include <sys/param.h> +#include <sys/systm.h> +#include <sys/kernel.h> +#include <sys/lock.h> +#include <sys/mutex.h> +#include <sys/proc.h> +#include <sys/rangelock.h> +#include <sys/resourcevar.h> +#include <sys/sdt.h> +#include <sys/smp.h> +#include <sys/sched.h> +#include <sys/sleepqueue.h> +#include <sys/selinfo.h> +#include <sys/turnstile.h> +#include <sys/ktr.h> +#include <sys/rwlock.h> +#include <sys/umtx.h> +#include <sys/cpuset.h> +#ifdef HWPMC_HOOKS +#include <sys/pmckern.h> +#endif + +#include <security/audit/audit.h> + +#include <vm/vm.h> +#include <vm/vm_extern.h> +#include <vm/uma.h> +#include <sys/eventhandler.h> + +SDT_PROVIDER_DECLARE(proc); +SDT_PROBE_DEFINE(proc, , , lwp_exit, lwp-exit); + + +/* + * thread related storage. + */ +static uma_zone_t thread_zone; + +TAILQ_HEAD(, thread) zombie_threads = TAILQ_HEAD_INITIALIZER(zombie_threads); +static struct mtx zombie_lock; +MTX_SYSINIT(zombie_lock, &zombie_lock, "zombie lock", MTX_SPIN); + +static void thread_zombie(struct thread *); + +#define TID_BUFFER_SIZE 1024 + +struct mtx tid_lock; +static struct unrhdr *tid_unrhdr; +static lwpid_t tid_buffer[TID_BUFFER_SIZE]; +static int tid_head, tid_tail; +static MALLOC_DEFINE(M_TIDHASH, "tidhash", "thread hash"); + +struct tidhashhead *tidhashtbl; +u_long tidhash; +struct rwlock tidhash_lock; + +static lwpid_t +tid_alloc(void) +{ + lwpid_t tid; + + tid = alloc_unr(tid_unrhdr); + if (tid != -1) + return (tid); + mtx_lock(&tid_lock); + if (tid_head == tid_tail) { + mtx_unlock(&tid_lock); + return (-1); + } + tid = tid_buffer[tid_head]; + tid_head = (tid_head + 1) % TID_BUFFER_SIZE; + mtx_unlock(&tid_lock); + return (tid); +} + +static void +tid_free(lwpid_t tid) +{ + lwpid_t tmp_tid = -1; + + mtx_lock(&tid_lock); + if ((tid_tail + 1) % TID_BUFFER_SIZE == tid_head) { + tmp_tid = tid_buffer[tid_head]; + tid_head = (tid_head + 1) % TID_BUFFER_SIZE; + } + tid_buffer[tid_tail] = tid; + tid_tail = (tid_tail + 1) % TID_BUFFER_SIZE; + mtx_unlock(&tid_lock); + if (tmp_tid != -1) + free_unr(tid_unrhdr, tmp_tid); +} + +/* + * Prepare a thread for use. + */ +static int +thread_ctor(void *mem, int size, void *arg, int flags) +{ + struct thread *td; + + td = (struct thread *)mem; + td->td_state = TDS_INACTIVE; + td->td_oncpu = NOCPU; + + td->td_tid = tid_alloc(); + + /* + * Note that td_critnest begins life as 1 because the thread is not + * running and is thereby implicitly waiting to be on the receiving + * end of a context switch. + */ + td->td_critnest = 1; + td->td_lend_user_pri = PRI_MAX; + EVENTHANDLER_INVOKE(thread_ctor, td); +#ifdef AUDIT + audit_thread_alloc(td); +#endif + umtx_thread_alloc(td); + return (0); +} + +/* + * Reclaim a thread after use. + */ +static void +thread_dtor(void *mem, int size, void *arg) +{ + struct thread *td; + + td = (struct thread *)mem; + +#ifdef INVARIANTS + /* Verify that this thread is in a safe state to free. */ + switch (td->td_state) { + case TDS_INHIBITED: + case TDS_RUNNING: + case TDS_CAN_RUN: + case TDS_RUNQ: + /* + * We must never unlink a thread that is in one of + * these states, because it is currently active. + */ + panic("bad state for thread unlinking"); + /* NOTREACHED */ + case TDS_INACTIVE: + break; + default: + panic("bad thread state"); + /* NOTREACHED */ + } +#endif +#ifdef AUDIT + audit_thread_free(td); +#endif + /* Free all OSD associated to this thread. */ + osd_thread_exit(td); + + EVENTHANDLER_INVOKE(thread_dtor, td); + tid_free(td->td_tid); +} + +/* + * Initialize type-stable parts of a thread (when newly created). + */ +static int +thread_init(void *mem, int size, int flags) +{ + struct thread *td; + + td = (struct thread *)mem; + + td->td_sleepqueue = sleepq_alloc(); + td->td_turnstile = turnstile_alloc(); + td->td_rlqe = NULL; + EVENTHANDLER_INVOKE(thread_init, td); + td->td_sched = (struct td_sched *)&td[1]; + umtx_thread_init(td); + td->td_kstack = 0; + return (0); +} + +/* + * Tear down type-stable parts of a thread (just before being discarded). + */ +static void +thread_fini(void *mem, int size) +{ + struct thread *td; + + td = (struct thread *)mem; + EVENTHANDLER_INVOKE(thread_fini, td); + rlqentry_free(td->td_rlqe); + turnstile_free(td->td_turnstile); + sleepq_free(td->td_sleepqueue); + umtx_thread_fini(td); + seltdfini(td); +} + +/* + * For a newly created process, + * link up all the structures and its initial threads etc. + * called from: + * {arch}/{arch}/machdep.c ia64_init(), init386() etc. + * proc_dtor() (should go away) + * proc_init() + */ +void +proc_linkup0(struct proc *p, struct thread *td) +{ + TAILQ_INIT(&p->p_threads); /* all threads in proc */ + proc_linkup(p, td); +} + +void +proc_linkup(struct proc *p, struct thread *td) +{ + + sigqueue_init(&p->p_sigqueue, p); + p->p_ksi = ksiginfo_alloc(1); + if (p->p_ksi != NULL) { + /* XXX p_ksi may be null if ksiginfo zone is not ready */ + p->p_ksi->ksi_flags = KSI_EXT | KSI_INS; + } + LIST_INIT(&p->p_mqnotifier); + p->p_numthreads = 0; + thread_link(td, p); +} + +/* + * Initialize global thread allocation resources. + */ +void +threadinit(void) +{ + + mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF); + + /* + * pid_max cannot be greater than PID_MAX. + * leave one number for thread0. + */ + tid_unrhdr = new_unrhdr(PID_MAX + 2, INT_MAX, &tid_lock); + + thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(), + thread_ctor, thread_dtor, thread_init, thread_fini, + 16 - 1, 0); + tidhashtbl = hashinit(maxproc / 2, M_TIDHASH, &tidhash); + rw_init(&tidhash_lock, "tidhash"); +} + +/* + * Place an unused thread on the zombie list. + * Use the slpq as that must be unused by now. + */ +void +thread_zombie(struct thread *td) +{ + mtx_lock_spin(&zombie_lock); + TAILQ_INSERT_HEAD(&zombie_threads, td, td_slpq); + mtx_unlock_spin(&zombie_lock); +} + +/* + * Release a thread that has exited after cpu_throw(). + */ +void +thread_stash(struct thread *td) +{ + atomic_subtract_rel_int(&td->td_proc->p_exitthreads, 1); + thread_zombie(td); +} + +/* + * Reap zombie resources. + */ +void +thread_reap(void) +{ + struct thread *td_first, *td_next; + + /* + * Don't even bother to lock if none at this instant, + * we really don't care about the next instant.. + */ + if (!TAILQ_EMPTY(&zombie_threads)) { + mtx_lock_spin(&zombie_lock); + td_first = TAILQ_FIRST(&zombie_threads); + if (td_first) + TAILQ_INIT(&zombie_threads); + mtx_unlock_spin(&zombie_lock); + while (td_first) { + td_next = TAILQ_NEXT(td_first, td_slpq); + if (td_first->td_ucred) + crfree(td_first->td_ucred); + thread_free(td_first); + td_first = td_next; + } + } +} + +/* + * Allocate a thread. + */ +struct thread * +thread_alloc(int pages) +{ + struct thread *td; + + thread_reap(); /* check if any zombies to get */ + + td = (struct thread *)uma_zalloc(thread_zone, M_WAITOK); + KASSERT(td->td_kstack == 0, ("thread_alloc got thread with kstack")); + if (!vm_thread_new(td, pages)) { + uma_zfree(thread_zone, td); + return (NULL); + } + cpu_thread_alloc(td); + return (td); +} + +int +thread_alloc_stack(struct thread *td, int pages) +{ + + KASSERT(td->td_kstack == 0, + ("thread_alloc_stack called on a thread with kstack")); + if (!vm_thread_new(td, pages)) + return (0); + cpu_thread_alloc(td); + return (1); +} + +/* + * Deallocate a thread. + */ +void +thread_free(struct thread *td) +{ + + lock_profile_thread_exit(td); + if (td->td_cpuset) + cpuset_rel(td->td_cpuset); + td->td_cpuset = NULL; + cpu_thread_free(td); + if (td->td_kstack != 0) + vm_thread_dispose(td); + uma_zfree(thread_zone, td); +} + +/* + * Discard the current thread and exit from its context. + * Always called with scheduler locked. + * + * Because we can't free a thread while we're operating under its context, + * push the current thread into our CPU's deadthread holder. This means + * we needn't worry about someone else grabbing our context before we + * do a cpu_throw(). + */ +void +thread_exit(void) +{ + uint64_t runtime, new_switchtime; + struct thread *td; + struct thread *td2; + struct proc *p; + int wakeup_swapper; + + td = curthread; + p = td->td_proc; + + PROC_SLOCK_ASSERT(p, MA_OWNED); + mtx_assert(&Giant, MA_NOTOWNED); + + PROC_LOCK_ASSERT(p, MA_OWNED); + KASSERT(p != NULL, ("thread exiting without a process")); + CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td, + (long)p->p_pid, td->td_name); + KASSERT(TAILQ_EMPTY(&td->td_sigqueue.sq_list), ("signal pending")); + +#ifdef AUDIT + AUDIT_SYSCALL_EXIT(0, td); +#endif + umtx_thread_exit(td); + /* + * drop FPU & debug register state storage, or any other + * architecture specific resources that + * would not be on a new untouched process. + */ + cpu_thread_exit(td); /* XXXSMP */ + + /* + * The last thread is left attached to the process + * So that the whole bundle gets recycled. Skip + * all this stuff if we never had threads. + * EXIT clears all sign of other threads when + * it goes to single threading, so the last thread always + * takes the short path. + */ + if (p->p_flag & P_HADTHREADS) { + if (p->p_numthreads > 1) { + thread_unlink(td); + td2 = FIRST_THREAD_IN_PROC(p); + sched_exit_thread(td2, td); + + /* + * The test below is NOT true if we are the + * sole exiting thread. P_STOPPED_SINGLE is unset + * in exit1() after it is the only survivor. + */ + if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { + if (p->p_numthreads == p->p_suspcount) { + thread_lock(p->p_singlethread); + wakeup_swapper = thread_unsuspend_one( + p->p_singlethread); + thread_unlock(p->p_singlethread); + if (wakeup_swapper) + kick_proc0(); + } + } + + atomic_add_int(&td->td_proc->p_exitthreads, 1); + PCPU_SET(deadthread, td); + } else { + /* + * The last thread is exiting.. but not through exit() + */ + panic ("thread_exit: Last thread exiting on its own"); + } + } +#ifdef HWPMC_HOOKS + /* + * If this thread is part of a process that is being tracked by hwpmc(4), + * inform the module of the thread's impending exit. + */ + if (PMC_PROC_IS_USING_PMCS(td->td_proc)) + PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); +#endif + PROC_UNLOCK(p); + + /* Do the same timestamp bookkeeping that mi_switch() would do. */ + new_switchtime = cpu_ticks(); + runtime = new_switchtime - PCPU_GET(switchtime); + td->td_runtime += runtime; + td->td_incruntime += runtime; + PCPU_SET(switchtime, new_switchtime); + PCPU_SET(switchticks, ticks); + PCPU_INC(cnt.v_swtch); + + /* Save our resource usage in our process. */ + td->td_ru.ru_nvcsw++; + ruxagg(p, td); + rucollect(&p->p_ru, &td->td_ru); + + thread_lock(td); + PROC_SUNLOCK(p); + td->td_state = TDS_INACTIVE; +#ifdef WITNESS + witness_thread_exit(td); +#endif + CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td); + sched_throw(td); + panic("I'm a teapot!"); + /* NOTREACHED */ +} + +/* + * Do any thread specific cleanups that may be needed in wait() + * called with Giant, proc and schedlock not held. + */ +void +thread_wait(struct proc *p) +{ + struct thread *td; + + mtx_assert(&Giant, MA_NOTOWNED); + KASSERT((p->p_numthreads == 1), ("Multiple threads in wait1()")); + td = FIRST_THREAD_IN_PROC(p); + /* Lock the last thread so we spin until it exits cpu_throw(). */ + thread_lock(td); + thread_unlock(td); + /* Wait for any remaining threads to exit cpu_throw(). */ + while (p->p_exitthreads) + sched_relinquish(curthread); + lock_profile_thread_exit(td); + cpuset_rel(td->td_cpuset); + td->td_cpuset = NULL; + cpu_thread_clean(td); + crfree(td->td_ucred); + thread_reap(); /* check for zombie threads etc. */ +} + +/* + * Link a thread to a process. + * set up anything that needs to be initialized for it to + * be used by the process. + */ +void +thread_link(struct thread *td, struct proc *p) +{ + + /* + * XXX This can't be enabled because it's called for proc0 before + * its lock has been created. + * PROC_LOCK_ASSERT(p, MA_OWNED); + */ + td->td_state = TDS_INACTIVE; + td->td_proc = p; + td->td_flags = TDF_INMEM; + + LIST_INIT(&td->td_contested); + LIST_INIT(&td->td_lprof[0]); + LIST_INIT(&td->td_lprof[1]); + sigqueue_init(&td->td_sigqueue, p); + callout_init(&td->td_slpcallout, CALLOUT_MPSAFE); + TAILQ_INSERT_HEAD(&p->p_threads, td, td_plist); + p->p_numthreads++; +} + +/* + * Convert a process with one thread to an unthreaded process. + */ +void +thread_unthread(struct thread *td) +{ + struct proc *p = td->td_proc; + + KASSERT((p->p_numthreads == 1), ("Unthreading with >1 threads")); + p->p_flag &= ~P_HADTHREADS; +} + +/* + * Called from: + * thread_exit() + */ +void +thread_unlink(struct thread *td) +{ + struct proc *p = td->td_proc; + + PROC_LOCK_ASSERT(p, MA_OWNED); + TAILQ_REMOVE(&p->p_threads, td, td_plist); + p->p_numthreads--; + /* could clear a few other things here */ + /* Must NOT clear links to proc! */ +} + +static int +calc_remaining(struct proc *p, int mode) +{ + int remaining; + + PROC_LOCK_ASSERT(p, MA_OWNED); + PROC_SLOCK_ASSERT(p, MA_OWNED); + if (mode == SINGLE_EXIT) + remaining = p->p_numthreads; + else if (mode == SINGLE_BOUNDARY) + remaining = p->p_numthreads - p->p_boundary_count; + else if (mode == SINGLE_NO_EXIT) + remaining = p->p_numthreads - p->p_suspcount; + else + panic("calc_remaining: wrong mode %d", mode); + return (remaining); +} + +/* + * Enforce single-threading. + * + * Returns 1 if the caller must abort (another thread is waiting to + * exit the process or similar). Process is locked! + * Returns 0 when you are successfully the only thread running. + * A process has successfully single threaded in the suspend mode when + * There are no threads in user mode. Threads in the kernel must be + * allowed to continue until they get to the user boundary. They may even + * copy out their return values and data before suspending. They may however be + * accelerated in reaching the user boundary as we will wake up + * any sleeping threads that are interruptable. (PCATCH). + */ +int +thread_single(int mode) +{ + struct thread *td; + struct thread *td2; + struct proc *p; + int remaining, wakeup_swapper; + + td = curthread; + p = td->td_proc; + mtx_assert(&Giant, MA_NOTOWNED); + PROC_LOCK_ASSERT(p, MA_OWNED); + + if ((p->p_flag & P_HADTHREADS) == 0) + return (0); + + /* Is someone already single threading? */ + if (p->p_singlethread != NULL && p->p_singlethread != td) + return (1); + + if (mode == SINGLE_EXIT) { + p->p_flag |= P_SINGLE_EXIT; + p->p_flag &= ~P_SINGLE_BOUNDARY; + } else { + p->p_flag &= ~P_SINGLE_EXIT; + if (mode == SINGLE_BOUNDARY) + p->p_flag |= P_SINGLE_BOUNDARY; + else + p->p_flag &= ~P_SINGLE_BOUNDARY; + } + p->p_flag |= P_STOPPED_SINGLE; + PROC_SLOCK(p); + p->p_singlethread = td; + remaining = calc_remaining(p, mode); + while (remaining != 1) { + if (P_SHOULDSTOP(p) != P_STOPPED_SINGLE) + goto stopme; + wakeup_swapper = 0; + FOREACH_THREAD_IN_PROC(p, td2) { + if (td2 == td) + continue; + thread_lock(td2); + td2->td_flags |= TDF_ASTPENDING | TDF_NEEDSUSPCHK; + if (TD_IS_INHIBITED(td2)) { + switch (mode) { + case SINGLE_EXIT: + if (TD_IS_SUSPENDED(td2)) + wakeup_swapper |= + thread_unsuspend_one(td2); + if (TD_ON_SLEEPQ(td2) && + (td2->td_flags & TDF_SINTR)) + wakeup_swapper |= + sleepq_abort(td2, EINTR); + break; + case SINGLE_BOUNDARY: + if (TD_IS_SUSPENDED(td2) && + !(td2->td_flags & TDF_BOUNDARY)) + wakeup_swapper |= + thread_unsuspend_one(td2); + if (TD_ON_SLEEPQ(td2) && + (td2->td_flags & TDF_SINTR)) + wakeup_swapper |= + sleepq_abort(td2, ERESTART); + break; + case SINGLE_NO_EXIT: + if (TD_IS_SUSPENDED(td2) && + !(td2->td_flags & TDF_BOUNDARY)) + wakeup_swapper |= + thread_unsuspend_one(td2); + if (TD_ON_SLEEPQ(td2) && + (td2->td_flags & TDF_SINTR)) + wakeup_swapper |= + sleepq_abort(td2, ERESTART); + break; + default: + break; + } + } +#ifdef SMP + else if (TD_IS_RUNNING(td2) && td != td2) { + forward_signal(td2); + } +#endif + thread_unlock(td2); + } + if (wakeup_swapper) + kick_proc0(); + remaining = calc_remaining(p, mode); + + /* + * Maybe we suspended some threads.. was it enough? + */ + if (remaining == 1) + break; + +stopme: + /* + * Wake us up when everyone else has suspended. + * In the mean time we suspend as well. + */ + thread_suspend_switch(td); + remaining = calc_remaining(p, mode); + } + if (mode == SINGLE_EXIT) { + /* + * We have gotten rid of all the other threads and we + * are about to either exit or exec. In either case, + * we try our utmost to revert to being a non-threaded + * process. + */ + p->p_singlethread = NULL; + p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT); + thread_unthread(td); + } + PROC_SUNLOCK(p); + return (0); +} + +/* + * Called in from locations that can safely check to see + * whether we have to suspend or at least throttle for a + * single-thread event (e.g. fork). + * + * Such locations include userret(). + * If the "return_instead" argument is non zero, the thread must be able to + * accept 0 (caller may continue), or 1 (caller must abort) as a result. + * + * The 'return_instead' argument tells the function if it may do a + * thread_exit() or suspend, or whether the caller must abort and back + * out instead. + * + * If the thread that set the single_threading request has set the + * P_SINGLE_EXIT bit in the process flags then this call will never return + * if 'return_instead' is false, but will exit. + * + * P_SINGLE_EXIT | return_instead == 0| return_instead != 0 + *---------------+--------------------+--------------------- + * 0 | returns 0 | returns 0 or 1 + * | when ST ends | immediately + *---------------+--------------------+--------------------- + * 1 | thread exits | returns 1 + * | | immediately + * 0 = thread_exit() or suspension ok, + * other = return error instead of stopping the thread. + * + * While a full suspension is under effect, even a single threading + * thread would be suspended if it made this call (but it shouldn't). + * This call should only be made from places where + * thread_exit() would be safe as that may be the outcome unless + * return_instead is set. + */ +int +thread_suspend_check(int return_instead) +{ + struct thread *td; + struct proc *p; + int wakeup_swapper; + + td = curthread; + p = td->td_proc; + mtx_assert(&Giant, MA_NOTOWNED); + PROC_LOCK_ASSERT(p, MA_OWNED); + while (P_SHOULDSTOP(p) || + ((p->p_flag & P_TRACED) && (td->td_dbgflags & TDB_SUSPEND))) { + if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { + KASSERT(p->p_singlethread != NULL, + ("singlethread not set")); + /* + * The only suspension in action is a + * single-threading. Single threader need not stop. + * XXX Should be safe to access unlocked + * as it can only be set to be true by us. + */ + if (p->p_singlethread == td) + return (0); /* Exempt from stopping. */ + } + if ((p->p_flag & P_SINGLE_EXIT) && return_instead) + return (EINTR); + + /* Should we goto user boundary if we didn't come from there? */ + if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && + (p->p_flag & P_SINGLE_BOUNDARY) && return_instead) + return (ERESTART); + + /* + * Ignore suspend requests for stop signals if they + * are deferred. + */ + if (P_SHOULDSTOP(p) == P_STOPPED_SIG && + td->td_flags & TDF_SBDRY) { + KASSERT(return_instead, + ("TDF_SBDRY set for unsafe thread_suspend_check")); + return (0); + } + + /* + * If the process is waiting for us to exit, + * this thread should just suicide. + * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE. + */ + if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) { + PROC_UNLOCK(p); + tidhash_remove(td); + PROC_LOCK(p); + tdsigcleanup(td); + PROC_SLOCK(p); + thread_stopped(p); + thread_exit(); + } + + PROC_SLOCK(p); + thread_stopped(p); + if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { + if (p->p_numthreads == p->p_suspcount + 1) { + thread_lock(p->p_singlethread); + wakeup_swapper = + thread_unsuspend_one(p->p_singlethread); + thread_unlock(p->p_singlethread); + if (wakeup_swapper) + kick_proc0(); + } + } + PROC_UNLOCK(p); + thread_lock(td); + /* + * When a thread suspends, it just + * gets taken off all queues. + */ + thread_suspend_one(td); + if (return_instead == 0) { + p->p_boundary_count++; + td->td_flags |= TDF_BOUNDARY; + } + PROC_SUNLOCK(p); + mi_switch(SW_INVOL | SWT_SUSPEND, NULL); + if (return_instead == 0) + td->td_flags &= ~TDF_BOUNDARY; + thread_unlock(td); + PROC_LOCK(p); + if (return_instead == 0) { + PROC_SLOCK(p); + p->p_boundary_count--; + PROC_SUNLOCK(p); + } + } + return (0); +} + +void +thread_suspend_switch(struct thread *td) +{ + struct proc *p; + + p = td->td_proc; + KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); + PROC_LOCK_ASSERT(p, MA_OWNED); + PROC_SLOCK_ASSERT(p, MA_OWNED); + /* + * We implement thread_suspend_one in stages here to avoid + * dropping the proc lock while the thread lock is owned. + */ + thread_stopped(p); + p->p_suspcount++; + PROC_UNLOCK(p); + thread_lock(td); + td->td_flags &= ~TDF_NEEDSUSPCHK; + TD_SET_SUSPENDED(td); + sched_sleep(td, 0); + PROC_SUNLOCK(p); + DROP_GIANT(); + mi_switch(SW_VOL | SWT_SUSPEND, NULL); + thread_unlock(td); + PICKUP_GIANT(); + PROC_LOCK(p); + PROC_SLOCK(p); +} + +void +thread_suspend_one(struct thread *td) +{ + struct proc *p = td->td_proc; + + PROC_SLOCK_ASSERT(p, MA_OWNED); + THREAD_LOCK_ASSERT(td, MA_OWNED); + KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); + p->p_suspcount++; + td->td_flags &= ~TDF_NEEDSUSPCHK; + TD_SET_SUSPENDED(td); + sched_sleep(td, 0); +} + +int +thread_unsuspend_one(struct thread *td) +{ + struct proc *p = td->td_proc; + + PROC_SLOCK_ASSERT(p, MA_OWNED); + THREAD_LOCK_ASSERT(td, MA_OWNED); + KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended")); + TD_CLR_SUSPENDED(td); + p->p_suspcount--; + return (setrunnable(td)); +} + +/* + * Allow all threads blocked by single threading to continue running. + */ +void +thread_unsuspend(struct proc *p) +{ + struct thread *td; + int wakeup_swapper; + + PROC_LOCK_ASSERT(p, MA_OWNED); + PROC_SLOCK_ASSERT(p, MA_OWNED); + wakeup_swapper = 0; + if (!P_SHOULDSTOP(p)) { + FOREACH_THREAD_IN_PROC(p, td) { + thread_lock(td); + if (TD_IS_SUSPENDED(td)) { + wakeup_swapper |= thread_unsuspend_one(td); + } + thread_unlock(td); + } + } else if ((P_SHOULDSTOP(p) == P_STOPPED_SINGLE) && + (p->p_numthreads == p->p_suspcount)) { + /* + * Stopping everything also did the job for the single + * threading request. Now we've downgraded to single-threaded, + * let it continue. + */ + thread_lock(p->p_singlethread); + wakeup_swapper = thread_unsuspend_one(p->p_singlethread); + thread_unlock(p->p_singlethread); + } + if (wakeup_swapper) + kick_proc0(); +} + +/* + * End the single threading mode.. + */ +void +thread_single_end(void) +{ + struct thread *td; + struct proc *p; + int wakeup_swapper; + + td = curthread; + p = td->td_proc; + PROC_LOCK_ASSERT(p, MA_OWNED); + p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY); + PROC_SLOCK(p); + p->p_singlethread = NULL; + wakeup_swapper = 0; + /* + * If there are other threads they may now run, + * unless of course there is a blanket 'stop order' + * on the process. The single threader must be allowed + * to continue however as this is a bad place to stop. + */ + if ((p->p_numthreads != 1) && (!P_SHOULDSTOP(p))) { + FOREACH_THREAD_IN_PROC(p, td) { + thread_lock(td); + if (TD_IS_SUSPENDED(td)) { + wakeup_swapper |= thread_unsuspend_one(td); + } + thread_unlock(td); + } + } + PROC_SUNLOCK(p); + if (wakeup_swapper) + kick_proc0(); +} + +struct thread * +thread_find(struct proc *p, lwpid_t tid) +{ + struct thread *td; + + PROC_LOCK_ASSERT(p, MA_OWNED); + FOREACH_THREAD_IN_PROC(p, td) { + if (td->td_tid == tid) + break; + } + return (td); +} + +/* Locate a thread by number; return with proc lock held. */ +struct thread * +tdfind(lwpid_t tid, pid_t pid) +{ +#define RUN_THRESH 16 + struct thread *td; + int run = 0; + + rw_rlock(&tidhash_lock); + LIST_FOREACH(td, TIDHASH(tid), td_hash) { + if (td->td_tid == tid) { + if (pid != -1 && td->td_proc->p_pid != pid) { + td = NULL; + break; + } + PROC_LOCK(td->td_proc); + if (td->td_proc->p_state == PRS_NEW) { + PROC_UNLOCK(td->td_proc); + td = NULL; + break; + } + if (run > RUN_THRESH) { + if (rw_try_upgrade(&tidhash_lock)) { + LIST_REMOVE(td, td_hash); + LIST_INSERT_HEAD(TIDHASH(td->td_tid), + td, td_hash); + rw_wunlock(&tidhash_lock); + return (td); + } + } + break; + } + run++; + } + rw_runlock(&tidhash_lock); + return (td); +} + +void +tidhash_add(struct thread *td) +{ + rw_wlock(&tidhash_lock); + LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash); + rw_wunlock(&tidhash_lock); +} + +void +tidhash_remove(struct thread *td) +{ + rw_wlock(&tidhash_lock); + LIST_REMOVE(td, td_hash); + rw_wunlock(&tidhash_lock); +} |
