summaryrefslogtreecommitdiff
path: root/src/thread
diff options
context:
space:
mode:
Diffstat (limited to 'src/thread')
-rw-r--r--src/thread/pthread_create.c24
-rw-r--r--src/thread/pthread_getschedparam.c2
-rw-r--r--src/thread/pthread_kill.c4
-rw-r--r--src/thread/pthread_setschedparam.c2
-rw-r--r--src/thread/pthread_setschedprio.c2
5 files changed, 18 insertions, 16 deletions
diff --git a/src/thread/pthread_create.c b/src/thread/pthread_create.c
index ac06d7a7..a86b5e1b 100644
--- a/src/thread/pthread_create.c
+++ b/src/thread/pthread_create.c
@@ -39,9 +39,11 @@ _Noreturn void __pthread_exit(void *result)
LOCK(self->exitlock);
- /* Mark this thread dead before decrementing count */
+ /* Access to target the exiting thread with syscalls that use
+ * its kernel tid is controlled by killlock. For detached threads,
+ * any use past this point would have undefined behavior, but for
+ * joinable threads it's a valid usage that must be handled. */
LOCK(self->killlock);
- self->dead = 1;
/* Block all signals before decrementing the live thread count.
* This is important to ensure that dynamically allocated TLS
@@ -49,20 +51,14 @@ _Noreturn void __pthread_exit(void *result)
* 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);
-
/* 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. */
+ * decrement, restore the tid, 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;
+ UNLOCK(self->killlock);
__restore_sigs(&set);
exit(0);
}
@@ -113,6 +109,12 @@ _Noreturn void __pthread_exit(void *result)
__unmapself(self->map_base, self->map_size);
}
+ /* After the kernel thread exits, its tid may be reused. Clear it
+ * to prevent inadvertent use and inform functions that would use
+ * it that it's no longer available. */
+ self->tid = 0;
+ UNLOCK(self->killlock);
+
for (;;) __syscall(SYS_exit, 0);
}
diff --git a/src/thread/pthread_getschedparam.c b/src/thread/pthread_getschedparam.c
index a994b637..05be4242 100644
--- a/src/thread/pthread_getschedparam.c
+++ b/src/thread/pthread_getschedparam.c
@@ -4,7 +4,7 @@ int pthread_getschedparam(pthread_t t, int *restrict policy, struct sched_param
{
int r;
LOCK(t->killlock);
- if (t->dead) {
+ if (!t->tid) {
r = ESRCH;
} else {
r = -__syscall(SYS_sched_getparam, t->tid, param);
diff --git a/src/thread/pthread_kill.c b/src/thread/pthread_kill.c
index 0a139231..6d70e626 100644
--- a/src/thread/pthread_kill.c
+++ b/src/thread/pthread_kill.c
@@ -4,8 +4,8 @@ int pthread_kill(pthread_t t, int sig)
{
int r;
LOCK(t->killlock);
- r = t->dead ? (sig+0U >= _NSIG ? EINVAL : 0)
- : -__syscall(SYS_tkill, t->tid, sig);
+ r = t->tid ? -__syscall(SYS_tkill, t->tid, sig)
+ : (sig+0U >= _NSIG ? EINVAL : 0);
UNLOCK(t->killlock);
return r;
}
diff --git a/src/thread/pthread_setschedparam.c b/src/thread/pthread_setschedparam.c
index 9e2fa456..ab45f2ff 100644
--- a/src/thread/pthread_setschedparam.c
+++ b/src/thread/pthread_setschedparam.c
@@ -4,7 +4,7 @@ int pthread_setschedparam(pthread_t t, int policy, const struct sched_param *par
{
int r;
LOCK(t->killlock);
- r = t->dead ? ESRCH : -__syscall(SYS_sched_setscheduler, t->tid, policy, param);
+ r = !t->tid ? ESRCH : -__syscall(SYS_sched_setscheduler, t->tid, policy, param);
UNLOCK(t->killlock);
return r;
}
diff --git a/src/thread/pthread_setschedprio.c b/src/thread/pthread_setschedprio.c
index dc745b42..c353f6b5 100644
--- a/src/thread/pthread_setschedprio.c
+++ b/src/thread/pthread_setschedprio.c
@@ -4,7 +4,7 @@ int pthread_setschedprio(pthread_t t, int prio)
{
int r;
LOCK(t->killlock);
- r = t->dead ? ESRCH : -__syscall(SYS_sched_setparam, t->tid, &prio);
+ r = !t->tid ? ESRCH : -__syscall(SYS_sched_setparam, t->tid, &prio);
UNLOCK(t->killlock);
return r;
}