X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;f=src%2Fthread%2Fpthread_create.c;h=6e2e48161753e03f0296e97383b7e081b711fb32;hb=3366a99b17847b58f2d8cc52cbb5d65deb824f8a;hp=0cd2d6c29260d5f92f0b13f5ca8e82f596be770c;hpb=23f21c304fd6a7592b70927e247129c5a2bc2390;p=musl diff --git a/src/thread/pthread_create.c b/src/thread/pthread_create.c index 0cd2d6c2..6e2e4816 100644 --- a/src/thread/pthread_create.c +++ b/src/thread/pthread_create.c @@ -1,6 +1,14 @@ +#define _GNU_SOURCE #include "pthread_impl.h" #include "stdio_impl.h" +#include "libc.h" #include +#include +#include + +void *__mmap(void *, size_t, int, int, int, off_t); +int __munmap(void *, size_t); +int __mprotect(void *, size_t, int); static void dummy_0() { @@ -8,12 +16,16 @@ static void dummy_0() weak_alias(dummy_0, __acquire_ptc); weak_alias(dummy_0, __release_ptc); weak_alias(dummy_0, __pthread_tsd_run_dtors); +weak_alias(dummy_0, __do_orphaned_stdio_locks); +weak_alias(dummy_0, __dl_thread_cleanup); -_Noreturn void pthread_exit(void *result) +_Noreturn void __pthread_exit(void *result) { - pthread_t self = pthread_self(); - int n; + pthread_t self = __pthread_self(); + sigset_t set; + self->canceldisable = 1; + self->cancelasync = 0; self->result = result; while (self->cancelbuf) { @@ -30,17 +42,74 @@ _Noreturn void pthread_exit(void *result) /* Mark this thread dead before decrementing count */ __lock(self->killlock); self->dead = 1; + + /* Block all signals before decrementing the live thread count. + * This is important to ensure that dynamically allocated TLS + * is not under-allocated/over-committed, and possibly for other + * reasons as well. */ + __block_all_sigs(&set); + + /* Wait to unlock the kill lock, which governs functions like + * pthread_kill which target a thread id, until signals have + * been blocked. This precludes observation of the thread id + * as a live thread (with application code running in it) after + * the thread was reported dead by ESRCH being returned. */ __unlock(self->killlock); - __syscall(SYS_rt_sigprocmask, SIG_BLOCK, SIGALL_SET, 0, _NSIG/8); + /* It's impossible to determine whether this is "the last thread" + * until performing the atomic decrement, since multiple threads + * could exit at the same time. For the last thread, revert the + * decrement and unblock signals to give the atexit handlers and + * stdio cleanup code a consistent state. */ + if (a_fetch_add(&libc.threads_minus_1, -1)==0) { + libc.threads_minus_1 = 0; + __restore_sigs(&set); + exit(0); + } + + /* Process robust list in userspace to handle non-pshared mutexes + * and the detached thread case where the robust list head will + * be invalid when the kernel would process it. */ + __vm_lock(); + volatile void *volatile *rp; + while ((rp=self->robust_list.head) && rp != &self->robust_list.head) { + pthread_mutex_t *m = (void *)((char *)rp + - offsetof(pthread_mutex_t, _m_next)); + int waiters = m->_m_waiters; + int priv = (m->_m_type & 128) ^ 128; + self->robust_list.pending = rp; + self->robust_list.head = *rp; + int cont = a_swap(&m->_m_lock, self->tid|0x40000000); + self->robust_list.pending = 0; + if (cont < 0 || waiters) + __wake(&m->_m_lock, 1, priv); + } + __vm_unlock(); - do n = libc.threads_minus_1; - while (n && a_cas(&libc.threads_minus_1, n, n-1)!=n); - if (!n) exit(0); + __do_orphaned_stdio_locks(); + __dl_thread_cleanup(); if (self->detached && self->map_base) { - if (self->detached == 2) - __syscall(SYS_set_tid_address, 0); + /* Detached threads must avoid the kernel clear_child_tid + * feature, since the virtual address will have been + * unmapped and possibly already reused by a new mapping + * at the time the kernel would perform the write. In + * the case of threads that started out detached, the + * initial clone flags are correct, but if the thread was + * detached later (== 2), we need to clear it here. */ + if (self->detached == 2) __syscall(SYS_set_tid_address, 0); + + /* Robust list will no longer be valid, and was already + * processed above, so unregister it with the kernel. */ + if (self->robust_list.off) + __syscall(SYS_set_robust_list, 0, 3*sizeof(long)); + + /* Since __unmapself bypasses the normal munmap code path, + * explicitly wait for vmlock holders first. */ + __vm_wait(); + + /* The following call unmaps the thread's stack mapping + * and then exits without touching the stack. */ __unmapself(self->map_base, self->map_size); } @@ -49,7 +118,7 @@ _Noreturn void pthread_exit(void *result) void __do_cleanup_push(struct __ptcb *cb) { - struct pthread *self = pthread_self(); + struct pthread *self = __pthread_self(); cb->__next = self->cancelbuf; self->cancelbuf = cb; } @@ -68,23 +137,34 @@ static int start(void *p) self->detached = 2; pthread_exit(0); } - __syscall(SYS_rt_sigprocmask, SIG_SETMASK, - self->sigmask, 0, _NSIG/8); + __restore_sigs(self->sigmask); } if (self->unblock_cancel) __syscall(SYS_rt_sigprocmask, SIG_UNBLOCK, SIGPT_SET, 0, _NSIG/8); - pthread_exit(self->start(self->start_arg)); + __pthread_exit(self->start(self->start_arg)); + return 0; +} + +static int start_c11(void *p) +{ + pthread_t self = p; + int (*start)(void*) = (int(*)(void*)) self->start; + __pthread_exit((void *)(uintptr_t)start(self->start_arg)); return 0; } #define ROUND(x) (((x)+PAGE_SIZE-1)&-PAGE_SIZE) /* pthread_key_create.c overrides this */ -static const size_t dummy = 0; +static volatile size_t dummy = 0; weak_alias(dummy, __pthread_tsd_size); +static void *dummy_tsd[1] = { 0 }; +weak_alias(dummy_tsd, __pthread_tsd_main); -static FILE *const dummy_file = 0; +volatile int __block_new_threads = 0; + +static FILE *volatile dummy_file = 0; weak_alias(dummy_file, __stdin_used); weak_alias(dummy_file, __stdout_used); weak_alias(dummy_file, __stderr_used); @@ -96,28 +176,35 @@ static void init_file_lock(FILE *f) void *__copy_tls(unsigned char *); -int pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict attrp, void *(*entry)(void *), void *restrict arg) +int __pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict attrp, void *(*entry)(void *), void *restrict arg) { - int ret; + int ret, c11 = (attrp == __ATTRP_C11_THREAD); size_t size, guard; - struct pthread *self = pthread_self(), *new; + struct pthread *self, *new; unsigned char *map = 0, *stack = 0, *tsd = 0, *stack_limit; - unsigned flags = 0x7d8f00; + unsigned flags = CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND + | CLONE_THREAD | CLONE_SYSVSEM | CLONE_SETTLS + | CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID | CLONE_DETACHED; int do_sched = 0; pthread_attr_t attr = {0}; - if (!self) return ENOSYS; + if (!libc.can_do_threads) return ENOSYS; + self = __pthread_self(); if (!libc.threaded) { - for (FILE *f=libc.ofl_head; f; f=f->next) + for (FILE *f=*__ofl_lock(); f; f=f->next) init_file_lock(f); + __ofl_unlock(); init_file_lock(__stdin_used); init_file_lock(__stdout_used); init_file_lock(__stderr_used); + __syscall(SYS_rt_sigprocmask, SIG_UNBLOCK, SIGPT_SET, 0, _NSIG/8); + self->tsd = (void **)__pthread_tsd_main; libc.threaded = 1; } - if (attrp) attr = *attrp; + if (attrp && !c11) attr = *attrp; __acquire_ptc(); + if (__block_new_threads) __wait(&__block_new_threads, 0, 1, 1); if (attr._a_stackaddr) { size_t need = libc.tls_size + __pthread_tsd_size; @@ -130,6 +217,7 @@ int pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict attrp if (need < size/8 && need < 2048) { tsd = stack - __pthread_tsd_size; stack = tsd - libc.tls_size; + memset(stack, 0, need); } else { size = ROUND(need); guard = 0; @@ -142,14 +230,14 @@ int pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict attrp if (!tsd) { if (guard) { - map = mmap(0, size, PROT_NONE, MAP_PRIVATE|MAP_ANON, -1, 0); + map = __mmap(0, size, PROT_NONE, MAP_PRIVATE|MAP_ANON, -1, 0); if (map == MAP_FAILED) goto fail; - if (mprotect(map+guard, size-guard, PROT_READ|PROT_WRITE)) { - munmap(map, size); + if (__mprotect(map+guard, size-guard, PROT_READ|PROT_WRITE)) { + __munmap(map, size); goto fail; } } else { - map = mmap(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0); + map = __mmap(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0); if (map == MAP_FAILED) goto fail; } tsd = map + size - __pthread_tsd_size; @@ -164,37 +252,35 @@ int pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict attrp new->map_size = size; new->stack = stack; new->stack_size = stack - stack_limit; - new->pid = self->pid; - new->errno_ptr = &new->errno_val; new->start = entry; new->start_arg = arg; new->self = new; new->tsd = (void *)tsd; + new->locale = &libc.global_locale; if (attr._a_detach) { new->detached = 1; - flags -= 0x200000; + flags -= CLONE_CHILD_CLEARTID; } if (attr._a_sched) { do_sched = new->startlock[0] = 1; - __syscall(SYS_rt_sigprocmask, SIG_BLOCK, - SIGALL_SET, self->sigmask, _NSIG/8); + __block_app_sigs(new->sigmask); } + new->robust_list.head = &new->robust_list.head; new->unblock_cancel = self->cancel; - new->canary = self->canary; + new->CANARY = self->CANARY; a_inc(&libc.threads_minus_1); - ret = __clone(start, stack, flags, new, &new->tid, TP_ADJ(new), &new->tid); + ret = __clone((c11 ? start_c11 : start), stack, flags, new, &new->tid, TP_ADJ(new), &new->tid); __release_ptc(); if (do_sched) { - __syscall(SYS_rt_sigprocmask, SIG_SETMASK, - new->sigmask, 0, _NSIG/8); + __restore_sigs(new->sigmask); } if (ret < 0) { a_dec(&libc.threads_minus_1); - if (map) munmap(map, size); + if (map) __munmap(map, size); return EAGAIN; } @@ -212,3 +298,6 @@ fail: __release_ptc(); return EAGAIN; } + +weak_alias(__pthread_exit, pthread_exit); +weak_alias(__pthread_create, pthread_create);