race condition fix: block all signals before decrementing thread count

[musl] / src / thread / pthread_create.c

diff --git a/src/thread/pthread_create.c b/src/thread/pthread_create.c
index 6fa484c..c73c521 100644 (file)
--- a/src/thread/pthread_create.c
+++ b/src/thread/pthread_create.c
@@ -1,6 +1,40 @@
 #include "pthread_impl.h"
 
-#define pthread_self __pthread_self
+void __pthread_unwind_next(struct __ptcb *cb)
+{
+       int i, j, not_finished;
+       pthread_t self;
+
+       if (cb->__next) longjmp((void *)cb->__next->__jb, 1);
+
+       self = pthread_self();
+       if (self->cancel) self->result = PTHREAD_CANCELLED;
+
+       LOCK(&self->exitlock);
+
+       not_finished = self->tsd_used;
+       for (j=0; not_finished && j<PTHREAD_DESTRUCTOR_ITERATIONS; j++) {
+               not_finished = 0;
+               for (i=0; i<PTHREAD_KEYS_MAX; i++) {
+                       if (self->tsd[i] && libc.tsd_keys[i]) {
+                               void *tmp = self->tsd[i];
+                               self->tsd[i] = 0;
+                               libc.tsd_keys[i](tmp);
+                               not_finished = 1;
+                       }
+               }
+       }
+
+       syscall4(__NR_sigprocmask, SIG_BLOCK, (long)(uint64_t[1]){-1}, 0, 8);
+
+       if (!a_fetch_add(&libc.threads_minus_1, -1))
+               exit(0);
+
+       if (self->detached && self->map_base)
+               __unmapself(self->map_base, self->map_size);
+
+       __syscall_exit(0);
+}
 
 static void docancel(struct pthread *self)
 {
@@ -10,13 +44,21 @@ static void docancel(struct pthread *self)
 
 static void cancel_handler(int sig, siginfo_t *si, void *ctx)
 {
-       struct pthread *self = pthread_self();
+       struct pthread *self = __pthread_self();
        self->cancel = 1;
        if (self->canceldisable || (!self->cancelasync && !self->cancelpoint))
                return;
        docancel(self);
 }
 
+static void cancelpt(int x)
+{
+       struct pthread *self = __pthread_self();
+       if (self->canceldisable) return;
+       self->cancelpoint = x;
+       if (self->cancel) docancel(self);
+}
+
 /* "rsyscall" is a mechanism by which a thread can synchronously force all
  * other threads to perform an arbitrary syscall. It is necessary to work
  * around the non-conformant implementation of setuid() et al on Linux,
@@ -50,7 +92,7 @@ static int rsyscall(int nr, long a, long b, long c, long d, long e, long f)
 {
        int i, ret;
        sigset_t set = { 0 };
-       struct pthread *self = pthread_self();
+       struct pthread *self = __pthread_self();
        sigaddset(&set, SIGSYSCALL);
 
        LOCK(&rs.lock);
@@ -90,14 +132,6 @@ static int rsyscall(int nr, long a, long b, long c, long d, long e, long f)
        return ret;
 }
 
-static void cancelpt(int x)
-{
-       struct pthread *self = pthread_self();
-       if (self->canceldisable) return;
-       self->cancelpoint = x;
-       if (self->cancel) docancel(self);
-}
-
 static void init_threads()
 {
        struct sigaction sa = { .sa_flags = SA_SIGINFO | SA_RESTART };
@@ -120,10 +154,7 @@ static int start(void *p)
        return 0;
 }
 
-#undef pthread_self
-
-#define CLONE_MAGIC 0x7d0f00
-int __clone(int (*)(void *), void *, int, void *, pid_t *, void *, pid_t *);
+int __uniclone(void *, int (*)(), void *);
 
 #define ROUND(x) (((x)+PAGE_SIZE-1)&-PAGE_SIZE)
 
@@ -144,8 +175,8 @@ int pthread_create(pthread_t *res, const pthread_attr_t *attr, void *(*entry)(vo
        if (!init && ++init) init_threads();
 
        if (!attr) attr = &default_attr;
-       guard = ROUND(attr->__guardsize + DEFAULT_GUARD_SIZE);
-       size = guard + ROUND(attr->__stacksize + DEFAULT_STACK_SIZE);
+       guard = ROUND(attr->_a_guardsize + DEFAULT_GUARD_SIZE);
+       size = guard + ROUND(attr->_a_stacksize + DEFAULT_STACK_SIZE);
        size += __pthread_tsd_size;
        map = mmap(0, size, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|MAP_ANON, -1, 0);
        if (!map) return EAGAIN;
@@ -161,7 +192,7 @@ int pthread_create(pthread_t *res, const pthread_attr_t *attr, void *(*entry)(vo
        new->start_arg = arg;
        new->self = new;
        new->tsd = (void *)tsd;
-       new->detached = attr->__detach;
+       new->detached = attr->_a_detach;
        new->attr = *attr;
        memcpy(new->tlsdesc, self->tlsdesc, sizeof new->tlsdesc);
        new->tlsdesc[1] = (uintptr_t)new;
@@ -173,8 +204,7 @@ int pthread_create(pthread_t *res, const pthread_attr_t *attr, void *(*entry)(vo
        while (rs.lock) __wait(&rs.lock, 0, 1, 1);
 
        a_inc(&libc.threads_minus_1);
-       ret = __clone(start, stack, CLONE_MAGIC, new,
-               &new->tid, &new->tlsdesc, &new->tid);
+       ret = __uniclone(stack, start, new);
 
        a_dec(&rs.blocks);
        if (rs.lock) __wake(&rs.blocks, 1, 1);
@@ -182,8 +212,15 @@ int pthread_create(pthread_t *res, const pthread_attr_t *attr, void *(*entry)(vo
        if (ret < 0) {
                a_dec(&libc.threads_minus_1);
                munmap(map, size);
-               return -ret;
+               return EAGAIN;
        }
        *res = new;
        return 0;
 }
+
+void pthread_exit(void *result)
+{
+       struct pthread *self = pthread_self();
+       self->result = result;
+       docancel(self);
+}