nsz Git - musl/blob - src/thread/pthread_create.c

   1 #include "pthread_impl.h"
   2 #include "stdio_impl.h"
   3
   4 static void dummy_0()
   5 {
   6 }
   7 weak_alias(dummy_0, __acquire_ptc);
   8 weak_alias(dummy_0, __release_ptc);
   9 weak_alias(dummy_0, __pthread_tsd_run_dtors);
  10
  11 _Noreturn void pthread_exit(void *result)
  12 {
  13         pthread_t self = pthread_self();
  14         int n;
  15
  16         self->result = result;
  17
  18         while (self->cancelbuf) {
  19                 void (*f)(void *) = self->cancelbuf->__f;
  20                 void *x = self->cancelbuf->__x;
  21                 self->cancelbuf = self->cancelbuf->__next;
  22                 f(x);
  23         }
  24
  25         __pthread_tsd_run_dtors();
  26
  27         __lock(self->exitlock);
  28
  29         /* Mark this thread dead before decrementing count */
  30         __lock(self->killlock);
  31         self->dead = 1;
  32         __unlock(self->killlock);
  33
  34         do n = libc.threads_minus_1;
  35         while (n && a_cas(&libc.threads_minus_1, n, n-1)!=n);
  36         if (!n) exit(0);
  37
  38         if (self->detached && self->map_base) {
  39                 if (self->detached == 2)
  40                         __syscall(SYS_set_tid_address, 0);
  41                 __syscall(SYS_rt_sigprocmask, SIG_BLOCK,
  42                         SIGALL_SET, 0, __SYSCALL_SSLEN);
  43                 __unmapself(self->map_base, self->map_size);
  44         }
  45
  46         for (;;) __syscall(SYS_exit, 0);
  47 }
  48
  49 void __do_cleanup_push(struct __ptcb *cb)
  50 {
  51         struct pthread *self = pthread_self();
  52         cb->__next = self->cancelbuf;
  53         self->cancelbuf = cb;
  54 }
  55
  56 void __do_cleanup_pop(struct __ptcb *cb)
  57 {
  58         __pthread_self()->cancelbuf = cb->__next;
  59 }
  60
  61 static int start(void *p)
  62 {
  63         pthread_t self = p;
  64         if (self->unblock_cancel)
  65                 __syscall(SYS_rt_sigprocmask, SIG_UNBLOCK,
  66                         SIGPT_SET, 0, __SYSCALL_SSLEN);
  67         pthread_exit(self->start(self->start_arg));
  68         return 0;
  69 }
  70
  71 #define ROUND(x) (((x)+PAGE_SIZE-1)&-PAGE_SIZE)
  72
  73 /* pthread_key_create.c overrides this */
  74 static const size_t dummy = 0;
  75 weak_alias(dummy, __pthread_tsd_size);
  76
  77 static FILE *const dummy_file = 0;
  78 weak_alias(dummy_file, __stdin_used);
  79 weak_alias(dummy_file, __stdout_used);
  80 weak_alias(dummy_file, __stderr_used);
  81
  82 static void init_file_lock(FILE *f)
  83 {
  84         if (f && f->lock<0) f->lock = 0;
  85 }
  86
  87 void *__copy_tls(unsigned char *);
  88
  89 int pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict attr, void *(*entry)(void *), void *restrict arg)
  90 {
  91         int ret;
  92         size_t size = DEFAULT_STACK_SIZE + DEFAULT_GUARD_SIZE;
  93         size_t guard = DEFAULT_GUARD_SIZE;
  94         struct pthread *self = pthread_self(), *new;
  95         unsigned char *map, *stack, *tsd;
  96         unsigned flags = 0x7d8f00;
  97
  98         if (!self) return ENOSYS;
  99         if (!libc.threaded) {
 100                 for (FILE *f=libc.ofl_head; f; f=f->next)
 101                         init_file_lock(f);
 102                 init_file_lock(__stdin_used);
 103                 init_file_lock(__stdout_used);
 104                 init_file_lock(__stderr_used);
 105                 libc.threaded = 1;
 106         }
 107
 108         __acquire_ptc();
 109
 110         if (attr && attr->_a_stackaddr) {
 111                 map = 0;
 112                 tsd = (void *)(attr->_a_stackaddr-__pthread_tsd_size & -16);
 113         } else {
 114                 if (attr) {
 115                         guard = ROUND(attr->_a_guardsize + DEFAULT_GUARD_SIZE);
 116                         size = guard + ROUND(attr->_a_stacksize
 117                                 + DEFAULT_STACK_SIZE + libc.tls_size);
 118                 }
 119                 size += __pthread_tsd_size;
 120                 if (guard) {
 121                         map = mmap(0, size, PROT_NONE, MAP_PRIVATE|MAP_ANON, -1, 0);
 122                         if (map == MAP_FAILED) return EAGAIN;
 123                         if (mprotect(map+guard, size-guard, PROT_READ|PROT_WRITE)) {
 124                                 munmap(map, size);
 125                                 return EAGAIN;
 126                         }
 127                 } else {
 128                         map = mmap(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0);
 129                         if (map == MAP_FAILED) return EAGAIN;
 130                 }
 131                 tsd = map + size - __pthread_tsd_size;
 132         }
 133         new = __copy_tls(stack = tsd - libc.tls_size);
 134         new->map_base = map;
 135         new->map_size = size;
 136         new->pid = self->pid;
 137         new->errno_ptr = &new->errno_val;
 138         new->start = entry;
 139         new->start_arg = arg;
 140         new->self = new;
 141         new->tsd = (void *)tsd;
 142         if (attr && attr->_a_detach) {
 143                 new->detached = 1;
 144                 flags -= 0x200000;
 145         }
 146         new->unblock_cancel = self->cancel;
 147         new->canary = self->canary;
 148
 149         a_inc(&libc.threads_minus_1);
 150         ret = __clone(start, stack, flags, new, &new->tid, new, &new->tid);
 151
 152         __release_ptc();
 153
 154         if (ret < 0) {
 155                 a_dec(&libc.threads_minus_1);
 156                 munmap(map, size);
 157                 return EAGAIN;
 158         }
 159         *res = new;
 160         return 0;
 161 }