diff options
Diffstat (limited to 'linuxthreads/manager.c')
| -rw-r--r-- | linuxthreads/manager.c | 400 |
1 files changed, 400 insertions, 0 deletions
diff --git a/linuxthreads/manager.c b/linuxthreads/manager.c new file mode 100644 index 0000000..325955d --- /dev/null +++ b/linuxthreads/manager.c @@ -0,0 +1,400 @@ +/* Linuxthreads - a simple clone()-based implementation of Posix */ +/* threads for Linux. */ +/* Copyright (C) 1996 Xavier Leroy (Xavier.Leroy@inria.fr) */ +/* */ +/* This program is free software; you can redistribute it and/or */ +/* modify it under the terms of the GNU Library General Public License */ +/* as published by the Free Software Foundation; either version 2 */ +/* of the License, or (at your option) any later version. */ +/* */ +/* This program is distributed in the hope that it will be useful, */ +/* but WITHOUT ANY WARRANTY; without even the implied warranty of */ +/* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the */ +/* GNU Library General Public License for more details. */ + +/* The "thread manager" thread: manages creation and termination of threads */ + +#include <errno.h> +#include <sched.h> +#include <stddef.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> +#include <sys/select.h> /* for select */ +#include <sys/mman.h> /* for mmap */ +#include <sys/time.h> +#include <sys/wait.h> /* for waitpid macros */ +#include <linux/tasks.h> + +#include "pthread.h" +#include "internals.h" +#include "spinlock.h" +#include "restart.h" + +/* Array of active threads. Entry 0 is reserved for the initial thread. */ + +struct pthread_handle_struct __pthread_handles[PTHREAD_THREADS_MAX] = +{ { 0, &__pthread_initial_thread}, /* All NULLs */ }; + +/* Mapping from stack segment to thread descriptor. */ +/* Stack segment numbers are also indices into the __pthread_handles array. */ +/* Stack segment number 0 is reserved for the initial thread. */ + +static inline pthread_descr thread_segment(int seg) +{ + return (pthread_descr)(THREAD_STACK_START_ADDRESS - (seg - 1) * STACK_SIZE) + - 1; +} + +/* Flag set in signal handler to record child termination */ + +static volatile int terminated_children = 0; + +/* Flag set when the initial thread is blocked on pthread_exit waiting + for all other threads to terminate */ + +static int main_thread_exiting = 0; + +/* Counter used to generate unique thread identifier. + Thread identifier is pthread_threads_counter + segment. */ + +static pthread_t pthread_threads_counter = 0; + +/* Forward declarations */ + +static int pthread_handle_create(pthread_t *thread, const pthread_attr_t *attr, + void * (*start_routine)(void *), void *arg, + sigset_t *mask, int father_pid); +static void pthread_handle_free(pthread_descr th); +static void pthread_handle_exit(pthread_descr issuing_thread, int exitcode); +static void pthread_reap_children(void); +static void pthread_kill_all_threads(int sig, int main_thread_also); + +/* The server thread managing requests for thread creation and termination */ + +int __pthread_manager(void *arg) +{ + int reqfd = (int)arg; + sigset_t mask; + fd_set readfds; + struct timeval timeout; + int n; + struct pthread_request request; + + /* If we have special thread_self processing, initialize it. */ +#ifdef INIT_THREAD_SELF + INIT_THREAD_SELF(&__pthread_manager_thread); +#endif + /* Set the error variable. */ + __pthread_manager_thread.p_errnop = &__pthread_manager_thread.p_errno; + __pthread_manager_thread.p_h_errnop = &__pthread_manager_thread.p_h_errno; + /* Block all signals except PTHREAD_SIG_RESTART */ + sigfillset(&mask); + sigdelset(&mask, PTHREAD_SIG_RESTART); + sigprocmask(SIG_SETMASK, &mask, NULL); + /* Enter server loop */ + while(1) { + FD_ZERO(&readfds); + FD_SET(reqfd, &readfds); + timeout.tv_sec = 2; + timeout.tv_usec = 0; + n = __select(FD_SETSIZE, &readfds, NULL, NULL, &timeout); + /* Check for termination of the main thread */ + if (getppid() == 1) { + pthread_kill_all_threads(SIGKILL, 0); + _exit(0); + } + /* Check for dead children */ + if (terminated_children) { + terminated_children = 0; + pthread_reap_children(); + } + /* Read and execute request */ + if (n == 1 && FD_ISSET(reqfd, &readfds)) { + n = __libc_read(reqfd, (char *)&request, sizeof(request)); + ASSERT(n == sizeof(request)); + switch(request.req_kind) { + case REQ_CREATE: + request.req_thread->p_retcode = + pthread_handle_create((pthread_t *) &request.req_thread->p_retval, + request.req_args.create.attr, + request.req_args.create.fn, + request.req_args.create.arg, + &request.req_args.create.mask, + request.req_thread->p_pid); + restart(request.req_thread); + break; + case REQ_FREE: + pthread_handle_free(request.req_args.free.thread); + break; + case REQ_PROCESS_EXIT: + pthread_handle_exit(request.req_thread, + request.req_args.exit.code); + break; + case REQ_MAIN_THREAD_EXIT: + main_thread_exiting = 1; + if (__pthread_main_thread->p_nextlive == __pthread_main_thread) { + restart(__pthread_main_thread); + return 0; + } + break; + } + } + } +} + +/* Process creation */ + +static int pthread_start_thread(void *arg) +{ + pthread_descr self = (pthread_descr) arg; + void * outcome; + /* Initialize special thread_self processing, if any. */ +#ifdef INIT_THREAD_SELF + INIT_THREAD_SELF(self); +#endif + /* Make sure our pid field is initialized, just in case we get there + before our father has initialized it. */ + self->p_pid = __getpid(); + /* Initial signal mask is that of the creating thread. (Otherwise, + we'd just inherit the mask of the thread manager.) */ + sigprocmask(SIG_SETMASK, &self->p_start_args.mask, NULL); + /* Set the scheduling policy and priority for the new thread, if needed */ + if (self->p_start_args.schedpolicy >= 0) + __sched_setscheduler(self->p_pid, self->p_start_args.schedpolicy, + &self->p_start_args.schedparam); + /* Run the thread code */ + outcome = self->p_start_args.start_routine(self->p_start_args.arg); + /* Exit with the given return value */ + pthread_exit(outcome); + return 0; +} + +static int pthread_handle_create(pthread_t *thread, const pthread_attr_t *attr, + void * (*start_routine)(void *), void *arg, + sigset_t * mask, int father_pid) +{ + size_t sseg; + int pid; + pthread_descr new_thread; + pthread_t new_thread_id; + int i; + + /* Find a free stack segment for the current stack */ + for (sseg = 1; ; sseg++) { + if (sseg >= PTHREAD_THREADS_MAX) return EAGAIN; + if (__pthread_handles[sseg].h_descr != NULL) continue; + new_thread = thread_segment(sseg); + /* Allocate space for stack and thread descriptor. */ + if (mmap((caddr_t)((char *)(new_thread+1) - INITIAL_STACK_SIZE), + INITIAL_STACK_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC, + MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED | MAP_GROWSDOWN, -1, 0) + != MAP_FAILED) break; + /* It seems part of this segment is already mapped. Try the next. */ + } + /* Allocate new thread identifier */ + pthread_threads_counter += PTHREAD_THREADS_MAX; + new_thread_id = sseg + pthread_threads_counter; + /* Initialize the thread descriptor */ + new_thread->p_nextwaiting = NULL; + new_thread->p_tid = new_thread_id; + new_thread->p_priority = 0; + new_thread->p_spinlock = &(__pthread_handles[sseg].h_spinlock); + new_thread->p_signal = 0; + new_thread->p_signal_jmp = NULL; + new_thread->p_cancel_jmp = NULL; + new_thread->p_terminated = 0; + new_thread->p_detached = attr == NULL ? 0 : attr->detachstate; + new_thread->p_exited = 0; + new_thread->p_retval = NULL; + new_thread->p_joining = NULL; + new_thread->p_cleanup = NULL; + new_thread->p_cancelstate = PTHREAD_CANCEL_ENABLE; + new_thread->p_canceltype = PTHREAD_CANCEL_DEFERRED; + new_thread->p_canceled = 0; + new_thread->p_errnop = &new_thread->p_errno; + new_thread->p_errno = 0; + new_thread->p_h_errnop = &new_thread->p_h_errno; + new_thread->p_h_errno = 0; + for (i = 0; i < PTHREAD_KEY_1STLEVEL_SIZE; i++) + new_thread->p_specific[i] = NULL; + /* Initialize the thread handle */ + __pthread_handles[sseg].h_spinlock = 0; /* should already be 0 */ + __pthread_handles[sseg].h_descr = new_thread; + /* Determine scheduling parameters for the thread */ + new_thread->p_start_args.schedpolicy = -1; + if (attr != NULL) { + switch(attr->inheritsched) { + case PTHREAD_EXPLICIT_SCHED: + new_thread->p_start_args.schedpolicy = attr->schedpolicy; + new_thread->p_start_args.schedparam = attr->schedparam; + break; + case PTHREAD_INHERIT_SCHED: + /* schedpolicy doesn't need to be set, only get priority */ + __sched_getparam(father_pid, &new_thread->p_start_args.schedparam); + break; + } + new_thread->p_priority = + new_thread->p_start_args.schedparam.sched_priority; + } + /* Finish setting up arguments to pthread_start_thread */ + new_thread->p_start_args.start_routine = start_routine; + new_thread->p_start_args.arg = arg; + new_thread->p_start_args.mask = *mask; + /* Do the cloning */ + pid = __clone(pthread_start_thread, (void **) new_thread, + CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND | + PTHREAD_SIG_RESTART, + new_thread); + /* Check if cloning succeeded */ + if (pid == -1) { + /* Free the stack */ + munmap((caddr_t)((char *)(new_thread+1) - INITIAL_STACK_SIZE), + INITIAL_STACK_SIZE); + __pthread_handles[sseg].h_descr = NULL; + return errno; + } + /* Insert new thread in doubly linked list of active threads */ + new_thread->p_prevlive = __pthread_main_thread; + new_thread->p_nextlive = __pthread_main_thread->p_nextlive; + __pthread_main_thread->p_nextlive->p_prevlive = new_thread; + __pthread_main_thread->p_nextlive = new_thread; + /* Set pid field of the new thread, in case we get there before the + child starts. */ + new_thread->p_pid = pid; + /* We're all set */ + *thread = new_thread_id; + return 0; +} + +/* Free the resources of a thread. */ + +static void pthread_free(pthread_descr th) +{ + pthread_handle handle; + ASSERT(th->p_exited); + /* Make the handle invalid */ + handle = thread_handle(th->p_tid); + acquire(&handle->h_spinlock); + handle->h_descr = NULL; + release(&handle->h_spinlock); + /* If initial thread, nothing to free */ + if (th == &__pthread_initial_thread) return; + /* Free the stack and thread descriptor area */ + munmap((caddr_t) ((char *)(th+1) - STACK_SIZE), STACK_SIZE); +} + +/* Handle threads that have exited */ + +static void pthread_exited(pid_t pid) +{ + pthread_descr th; + int detached; + /* Find thread with that pid */ + for (th = __pthread_main_thread->p_nextlive; + th != __pthread_main_thread; + th = th->p_nextlive) { + if (th->p_pid == pid) { + /* Remove thread from list of active threads */ + th->p_nextlive->p_prevlive = th->p_prevlive; + th->p_prevlive->p_nextlive = th->p_nextlive; + /* Mark thread as exited, and if detached, free its resources */ + acquire(th->p_spinlock); + th->p_exited = 1; + detached = th->p_detached; + release(th->p_spinlock); + if (detached) pthread_free(th); + break; + } + } + /* If all threads have exited and the main thread is pending on a + pthread_exit, wake up the main thread and terminate ourselves. */ + if (main_thread_exiting && + __pthread_main_thread->p_nextlive == __pthread_main_thread) { + restart(__pthread_main_thread); + _exit(0); + } +} + +static void pthread_reap_children(void) +{ + pid_t pid; + int status; + + while ((pid = __libc_waitpid(-1, &status, WNOHANG | __WCLONE)) > 0) { + pthread_exited(pid); + if (WIFSIGNALED(status)) { + /* If a thread died due to a signal, send the same signal to + all other threads, including the main thread. */ + pthread_kill_all_threads(WTERMSIG(status), 1); + _exit(0); + } + } +} + +/* Free the resources of a thread */ + +static void pthread_handle_free(pthread_descr th) +{ + acquire(th->p_spinlock); + if (th->p_exited) { + release(th->p_spinlock); + pthread_free(th); + } else { + /* The Unix process of the thread is still running. + Mark the thread as detached so that the thread manager will + deallocate its resources when the Unix process exits. */ + th->p_detached = 1; + release(th->p_spinlock); + } +} + +/* Send a signal to all running threads */ + +static void pthread_kill_all_threads(int sig, int main_thread_also) +{ + pthread_descr th; + for (th = __pthread_main_thread->p_nextlive; + th != __pthread_main_thread; + th = th->p_nextlive) { + kill(th->p_pid, sig); + } + if (main_thread_also) { + kill(__pthread_main_thread->p_pid, sig); + } +} + +/* Process-wide exit() */ + +static void pthread_handle_exit(pthread_descr issuing_thread, int exitcode) +{ + pthread_descr th; + __pthread_exit_requested = 1; + __pthread_exit_code = exitcode; + /* Send the CANCEL signal to all running threads, including the main + thread, but excluding the thread from which the exit request originated + (that thread must complete the exit, e.g. calling atexit functions + and flushing stdio buffers). */ + for (th = issuing_thread->p_nextlive; + th != issuing_thread; + th = th->p_nextlive) { + kill(th->p_pid, PTHREAD_SIG_CANCEL); + } + /* Now, wait for all these threads, so that they don't become zombies + and their times are properly added to the thread manager's times. */ + for (th = issuing_thread->p_nextlive; + th != issuing_thread; + th = th->p_nextlive) { + waitpid(th->p_pid, NULL, __WCLONE); + } + restart(issuing_thread); + _exit(0); +} + +/* Handler for PTHREAD_SIG_RESTART in thread manager thread */ + +void __pthread_manager_sighandler(int sig) +{ + terminated_children = 1; +} |