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https://github.com/jart/cosmopolitan.git
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Implement pthread_atfork()
If threads are being used, then fork() will now acquire and release and runtime locks so that fork() may be safely used from threads. This also makes vfork() thread safe, because pthread mutexes will do nothing when the process is a child of vfork(). More torture tests have been written to confirm this all works like a charm. Additionally: - Invent hexpcpy() api - Rename nsync_malloc_() to kmalloc() - Complete posix named semaphore implementation - Make pthread_create() asynchronous signal safe - Add rm, rmdir, and touch to command interpreter builtins - Invent sigisprecious() and modify sigset functions to use it - Add unit tests for posix_spawn() attributes and fix its bugs One unresolved problem is the reclaiming of *NSYNC waiter memory in the forked child processes, within apps which have threads waiting on locks
This commit is contained in:
Justine Tunney
parent
64c284003d
commit
60cb435cb4
124 changed files with 2169 additions and 718 deletions
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@ -21,6 +21,7 @@
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#include "libc/calls/sched-sysv.internal.h"
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#include "libc/calls/state.internal.h"
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#include "libc/calls/struct/sigaltstack.h"
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#include "libc/calls/struct/sigset.h"
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#include "libc/calls/syscall-sysv.internal.h"
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#include "libc/dce.h"
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#include "libc/errno.h"
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@ -41,6 +42,7 @@
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#include "libc/sysv/consts/clone.h"
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#include "libc/sysv/consts/map.h"
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#include "libc/sysv/consts/prot.h"
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#include "libc/sysv/consts/sig.h"
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#include "libc/sysv/consts/ss.h"
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#include "libc/sysv/errfuns.h"
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#include "libc/thread/posixthread.internal.h"
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@ -52,6 +54,7 @@
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STATIC_YOINK("nsync_mu_lock");
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STATIC_YOINK("nsync_mu_unlock");
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STATIC_YOINK("_pthread_atfork");
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#define MAP_ANON_OPENBSD 0x1000
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#define MAP_STACK_OPENBSD 0x4000
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@ -76,30 +79,6 @@ void _pthread_free(struct PosixThread *pt) {
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free(pt);
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}
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void _pthread_funlock(pthread_mutex_t *mu, int parent_tid) {
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if (mu->_type == PTHREAD_MUTEX_NORMAL ||
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(atomic_load_explicit(&mu->_lock, memory_order_relaxed) &&
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mu->_owner != parent_tid)) {
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atomic_store_explicit(&mu->_lock, 0, memory_order_relaxed);
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mu->_nsync = 0;
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mu->_depth = 0;
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mu->_owner = 0;
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}
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}
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void _pthread_atfork(int parent_tid) {
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FILE *f;
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if (_weaken(dlmalloc_atfork)) _weaken(dlmalloc_atfork)();
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_pthread_funlock(&__fds_lock_obj, parent_tid);
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_pthread_funlock(&__sig_lock_obj, parent_tid);
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_pthread_funlock(&__fflush_lock_obj, parent_tid);
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for (int i = 0; i < __fflush.handles.i; ++i) {
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if ((f = __fflush.handles.p[i])) {
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_pthread_funlock((pthread_mutex_t *)f->lock, parent_tid);
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}
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}
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}
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static int PosixThread(void *arg, int tid) {
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struct PosixThread *pt = arg;
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enum PosixThreadStatus status;
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@ -118,6 +97,7 @@ static int PosixThread(void *arg, int tid) {
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// set long jump handler so pthread_exit can bring control back here
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if (!setjmp(pt->exiter)) {
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__get_tls()->tib_pthread = (pthread_t)pt;
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sigprocmask(SIG_SETMASK, &pt->sigmask, 0);
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pt->rc = pt->start_routine(pt->arg);
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// ensure pthread_cleanup_pop(), and pthread_exit() popped cleanup
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_npassert(!pt->cleanup);
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@ -158,62 +138,12 @@ static int FixupCustomStackOnOpenbsd(pthread_attr_t *attr) {
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}
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}
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/**
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* Creates thread, e.g.
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*
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* void *worker(void *arg) {
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* fputs(arg, stdout);
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* return "there\n";
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* }
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*
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* int main() {
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* void *result;
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* pthread_t id;
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* pthread_create(&id, 0, worker, "hi ");
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* pthread_join(id, &result);
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* fputs(result, stdout);
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* }
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*
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* Here's the OSI model of threads in Cosmopolitan:
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*
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* ┌──────────────────┐
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* │ pthread_create() │ - Standard
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* └─────────┬────────┘ Abstraction
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* ┌─────────┴────────┐
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* │ clone() │ - Polyfill
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* └─────────┬────────┘
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* ┌────────┬──┴┬─┬─┬─────────┐ - Kernel
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* ┌─────┴─────┐ │ │ │┌┴──────┐ │ Interfaces
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* │ sys_clone │ │ │ ││ tfork │ ┌┴─────────────┐
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* └───────────┘ │ │ │└───────┘ │ CreateThread │
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* ┌───────────────┴──┐│┌┴────────┐ └──────────────┘
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* │ bsdthread_create │││ thr_new │
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* └──────────────────┘│└─────────┘
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* ┌───────┴──────┐
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* │ _lwp_create │
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* └──────────────┘
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*
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* @param thread if non-null is used to output the thread id
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* upon successful completion
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* @param attr points to launch configuration, or may be null
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* to use sensible defaults; it must be initialized using
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* pthread_attr_init()
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* @param start_routine is your thread's callback function
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* @param arg is an arbitrary value passed to `start_routine`
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* @return 0 on success, or errno on error
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* @raise EAGAIN if resources to create thread weren't available
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* @raise EINVAL if `attr` was supplied and had unnaceptable data
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* @raise EPERM if scheduling policy was requested and user account
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* isn't authorized to use it
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* @returnserrno
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* @threadsafe
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*/
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errno_t pthread_create(pthread_t *thread, const pthread_attr_t *attr,
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void *(*start_routine)(void *), void *arg) {
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static errno_t pthread_create_impl(pthread_t *thread,
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const pthread_attr_t *attr,
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void *(*start_routine)(void *), void *arg,
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sigset_t oldsigs) {
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int rc, e = errno;
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struct PosixThread *pt;
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__require_tls();
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_pthread_zombies_decimate();
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// create posix thread object
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if (!(pt = calloc(1, sizeof(struct PosixThread)))) {
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@ -323,6 +253,7 @@ errno_t pthread_create(pthread_t *thread, const pthread_attr_t *attr,
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}
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// launch PosixThread(pt) in new thread
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pt->sigmask = oldsigs;
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if (clone(PosixThread, pt->attr.__stackaddr,
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pt->attr.__stacksize - (IsOpenbsd() ? 16 : 0),
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CLONE_VM | CLONE_THREAD | CLONE_FS | CLONE_FILES | CLONE_SIGHAND |
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@ -340,3 +271,66 @@ errno_t pthread_create(pthread_t *thread, const pthread_attr_t *attr,
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}
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return 0;
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}
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/**
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* Creates thread, e.g.
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*
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* void *worker(void *arg) {
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* fputs(arg, stdout);
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* return "there\n";
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* }
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*
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* int main() {
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* void *result;
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* pthread_t id;
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* pthread_create(&id, 0, worker, "hi ");
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* pthread_join(id, &result);
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* fputs(result, stdout);
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* }
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*
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* Here's the OSI model of threads in Cosmopolitan:
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*
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* ┌──────────────────┐
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* │ pthread_create() │ - Standard
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* └─────────┬────────┘ Abstraction
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* ┌─────────┴────────┐
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* │ clone() │ - Polyfill
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* └─────────┬────────┘
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* ┌────────┬──┴┬─┬─┬─────────┐ - Kernel
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* ┌─────┴─────┐ │ │ │┌┴──────┐ │ Interfaces
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* │ sys_clone │ │ │ ││ tfork │ ┌┴─────────────┐
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* └───────────┘ │ │ │└───────┘ │ CreateThread │
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* ┌───────────────┴──┐│┌┴────────┐ └──────────────┘
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* │ bsdthread_create │││ thr_new │
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* └──────────────────┘│└─────────┘
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* ┌───────┴──────┐
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* │ _lwp_create │
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* └──────────────┘
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*
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* @param thread if non-null is used to output the thread id
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* upon successful completion
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* @param attr points to launch configuration, or may be null
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* to use sensible defaults; it must be initialized using
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* pthread_attr_init()
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* @param start_routine is your thread's callback function
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* @param arg is an arbitrary value passed to `start_routine`
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* @return 0 on success, or errno on error
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* @raise EAGAIN if resources to create thread weren't available
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* @raise EINVAL if `attr` was supplied and had unnaceptable data
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* @raise EPERM if scheduling policy was requested and user account
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* isn't authorized to use it
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* @returnserrno
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* @threadsafe
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*/
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errno_t pthread_create(pthread_t *thread, const pthread_attr_t *attr,
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void *(*start_routine)(void *), void *arg) {
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errno_t rc;
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sigset_t blocksigs, oldsigs;
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__require_tls();
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_pthread_zombies_decimate();
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sigfillset(&blocksigs);
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_npassert(!sigprocmask(SIG_SETMASK, &blocksigs, &oldsigs));
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rc = pthread_create_impl(thread, attr, start_routine, arg, oldsigs);
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_npassert(!sigprocmask(SIG_SETMASK, &oldsigs, 0));
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return rc;
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}
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