X-Git-Url: http://nsz.repo.hu/git/?p=musl;a=blobdiff_plain;f=src%2Fthread%2Fpthread_create.c;h=c6a23955bdd6dde5b12ace70b74130bd2abf1c6d;hp=6f1bb0e8172b3c8045b4fa0867071c3118dd1e6c;hb=1ebde9c3a228e8daa4bdba98046556b4b6829f5e;hpb=fd80cfa00b34ec81b3049b98c66f6a45301ca6c4

diff --git a/src/thread/pthread_create.c b/src/thread/pthread_create.c
index 6f1bb0e8..c6a23955 100644
--- a/src/thread/pthread_create.c
+++ b/src/thread/pthread_create.c
@@ -1,5 +1,11 @@
 #include "pthread_impl.h"
 
+static void dummy_0()
+{
+}
+weak_alias(dummy_0, __rsyscall_lock);
+weak_alias(dummy_0, __rsyscall_unlock);
+
 static void dummy_1(pthread_t self)
 {
 }
@@ -12,11 +18,13 @@ weak_alias(dummy_1, __pthread_tsd_run_dtors);
 
 void __pthread_unwind_next(struct __ptcb *cb)
 {
-	pthread_t self;
+	pthread_t self = pthread_self();
+	int n;
 
-	if (cb->__next) longjmp((void *)cb->__next->__jb, 1);
-
-	self = pthread_self();
+	if (cb->__next) {
+		self->cancelbuf = cb->__next->__next;
+		longjmp((void *)cb->__next->__jb, 1);
+	}
 
 	LOCK(&self->exitlock);
 
@@ -25,143 +33,16 @@ void __pthread_unwind_next(struct __ptcb *cb)
 	/* Mark this thread dead before decrementing count */
 	self->dead = 1;
 
-	if (!a_fetch_add(&libc.threads_minus_1, -1))
-		exit(0);
+	do n = libc.threads_minus_1;
+	while (n && a_cas(&libc.threads_minus_1, n, n-1)!=n);
+	if (!n) exit(0);
 
 	if (self->detached && self->map_base) {
-		syscall(__NR_rt_sigprocmask, SIG_BLOCK, (long)(uint64_t[1]){-1},0,8);
+		__syscall(SYS_rt_sigprocmask, SIG_BLOCK, (long)(uint64_t[1]){-1},0,8);
 		__unmapself(self->map_base, self->map_size);
 	}
 
-	syscall(SYS_exit, 0);
-}
-
-static void docancel(struct pthread *self)
-{
-	struct __ptcb cb = { .__next = self->cancelbuf };
-	self->canceldisable = 1;
-	self->cancelasync = 0;
-	__pthread_unwind_next(&cb);
-}
-
-static void cancel_handler(int sig, siginfo_t *si, void *ctx)
-{
-	struct pthread *self = __pthread_self();
-	if (!self->cancel) {
-		if (si->si_code == SI_TIMER && libc.sigtimer)
-			libc.sigtimer(sig, si, ctx);
-		return;
-	}
-	if (self->canceldisable) return;
-	if (self->cancelasync || (self->cancelpoint==1 && PC_AT_SYS(ctx)))
-		docancel(self);
-}
-
-static void cancelpt(int x)
-{
-	struct pthread *self = __pthread_self();
-	if (self->canceldisable) return;
-	if ((self->cancelpoint+=x)==1 && x>=0 && 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,
- * which affect only the calling thread and not the whole process. This
- * implementation performs some tricks with signal delivery to work around
- * the fact that it does not keep any list of threads in userspace. */
-
-static struct {
-	volatile int lock, hold, blocks, cnt;
-	unsigned long arg[6];
-	int nr;
-	int err;
-} rs;
-
-static void rsyscall_handler(int sig, siginfo_t *si, void *ctx)
-{
-	struct pthread *self = __pthread_self();
-
-	if (si->si_code > 0 || si->si_pid != self->pid ||
-		rs.cnt == libc.threads_minus_1) return;
-
-	/* Threads which have already decremented themselves from the
-	 * thread count must not increment rs.cnt or otherwise act. */
-	if (self->dead) {
-		__wait(&rs.hold, 0, 1, 1);
-		return;
-	}
-
-	if (syscall(rs.nr, rs.arg[0], rs.arg[1], rs.arg[2],
-		rs.arg[3], rs.arg[4], rs.arg[5]) < 0 && !rs.err) rs.err=errno;
-
-	a_inc(&rs.cnt);
-	__wake(&rs.cnt, 1, 1);
-	while(rs.hold)
-		__wait(&rs.hold, 0, 1, 1);
-	a_dec(&rs.cnt);
-	if (!rs.cnt) __wake(&rs.cnt, 1, 1);
-}
-
-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();
-	sigaddset(&set, SIGSYSCALL);
-
-	LOCK(&rs.lock);
-	while ((i=rs.blocks))
-		__wait(&rs.blocks, 0, i, 1);
-
-	__libc_sigprocmask(SIG_BLOCK, &set, 0);
-
-	rs.nr = nr;
-	rs.arg[0] = a; rs.arg[1] = b;
-	rs.arg[2] = c; rs.arg[3] = d;
-	rs.arg[4] = d; rs.arg[5] = f;
-	rs.hold = 1;
-	rs.err = 0;
-	rs.cnt = 0;
-
-	/* Dispatch signals until all threads respond */
-	for (i=libc.threads_minus_1; i; i--)
-		sigqueue(self->pid, SIGSYSCALL, (union sigval){0});
-	while ((i=rs.cnt) < libc.threads_minus_1) {
-		sigqueue(self->pid, SIGSYSCALL, (union sigval){0});
-		__wait(&rs.cnt, 0, i, 1);
-	}
-
-	/* Handle any lingering signals with no-op */
-	__libc_sigprocmask(SIG_UNBLOCK, &set, 0);
-
-	/* Resume other threads' signal handlers and wait for them */
-	rs.hold = 0;
-	__wake(&rs.hold, -1, 0);
-	while((i=rs.cnt)) __wait(&rs.cnt, 0, i, 1);
-
-	if (rs.err) errno = rs.err, ret = -1;
-	else ret = syscall(nr, a, b, c, d, e, f);
-
-	UNLOCK(&rs.lock);
-	return ret;
-}
-
-static void init_threads()
-{
-	struct sigaction sa = { .sa_flags = SA_SIGINFO | SA_RESTART };
-	libc.lock = __lock;
-	libc.lockfile = __lockfile;
-	libc.cancelpt = cancelpt;
-	libc.rsyscall = rsyscall;
-	sa.sa_sigaction = cancel_handler;
-	__libc_sigaction(SIGCANCEL, &sa, 0);
-	sigaddset(&sa.sa_mask, SIGSYSCALL);
-	sigaddset(&sa.sa_mask, SIGCANCEL);
-	sa.sa_sigaction = rsyscall_handler;
-	__libc_sigaction(SIGSYSCALL, &sa, 0);
-	sigprocmask(SIG_UNBLOCK, &sa.sa_mask, 0);
+	__syscall(SYS_exit, 0);
 }
 
 static int start(void *p)
@@ -187,15 +68,21 @@ weak_alias(dummy, __pthread_tsd_size);
 
 int pthread_create(pthread_t *res, const pthread_attr_t *attr, void *(*entry)(void *), void *arg)
 {
-	static int init;
 	int ret;
 	size_t size, guard;
 	struct pthread *self = pthread_self(), *new;
 	unsigned char *map, *stack, *tsd;
-	static const pthread_attr_t default_attr;
+	const pthread_attr_t default_attr = { 0 };
 
-	if (!self) return errno = ENOSYS;
-	if (!init && ++init) init_threads();
+	if (!self) return ENOSYS;
+	if (!libc.threaded) {
+		sigset_t set;
+		sigemptyset(&set);
+		sigaddset(&set, SIGSYSCALL);
+		sigaddset(&set, SIGCANCEL);
+		__libc_sigprocmask(SIG_UNBLOCK, &set, 0);
+		libc.threaded = 1;
+	}
 
 	if (!attr) attr = &default_attr;
 	guard = ROUND(attr->_a_guardsize + DEFAULT_GUARD_SIZE);
@@ -218,21 +105,16 @@ int pthread_create(pthread_t *res, const pthread_attr_t *attr, void *(*entry)(vo
 	new->detached = attr->_a_detach;
 	new->attr = *attr;
 	new->unblock_cancel = self->cancel;
-	new->result = PTHREAD_CANCELED;
 	memcpy(new->tlsdesc, self->tlsdesc, sizeof new->tlsdesc);
 	new->tlsdesc[1] = (uintptr_t)new;
 	stack = (void *)((uintptr_t)new-1 & ~(uintptr_t)15);
 
-	/* We must synchronize new thread creation with rsyscall
-	 * delivery. This looks to be the least expensive way: */
-	a_inc(&rs.blocks);
-	while (rs.lock) __wait(&rs.lock, 0, 1, 1);
+	__rsyscall_lock();
 
 	a_inc(&libc.threads_minus_1);
 	ret = __uniclone(stack, start, new);
 
-	a_dec(&rs.blocks);
-	if (rs.lock) __wake(&rs.blocks, 1, 1);
+	__rsyscall_unlock();
 
 	if (ret < 0) {
 		a_dec(&libc.threads_minus_1);
@@ -246,6 +128,9 @@ int pthread_create(pthread_t *res, const pthread_attr_t *attr, void *(*entry)(vo
 void pthread_exit(void *result)
 {
 	struct pthread *self = pthread_self();
+	struct __ptcb cb = { .__next = self->cancelbuf };
 	self->result = result;
-	docancel(self);
+	self->canceldisable = 1;
+	self->cancelasync = 0;
+	__pthread_unwind_next(&cb);
 }