From 1b1274f728c268fba30685966174ff813115ae11 Mon Sep 17 00:00:00 2001 From: normal Date: Mon, 27 Aug 2018 23:29:44 +0000 Subject: thread_pthread.c: fix deadlock on test_thread.rb::test_signal_at_join Fixes: r64575 ("avoid lock ping-pong in do_gvl_timer & ubf_select") git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@64579 b2dd03c8-39d4-4d8f-98ff-823fe69b080e --- thread_pthread.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/thread_pthread.c b/thread_pthread.c index fa79b03c55..dca30bd026 100644 --- a/thread_pthread.c +++ b/thread_pthread.c @@ -1320,6 +1320,7 @@ ubf_select(void *ptr) { rb_thread_t *th = (rb_thread_t *)ptr; rb_vm_t *vm = th->vm; + const rb_thread_t *cur = ruby_thread_from_native(); /* may be 0 */ register_ubf_list(th); @@ -1328,9 +1329,12 @@ ubf_select(void *ptr) * Therefore, we repeatedly call ubf_wakeup_thread() until a target thread * exit from ubf function. We must have a timer to perform this operation. * We use double-checked locking here because this function may be called - * while vm->gvl.lock is held in do_gvl_timer + * while vm->gvl.lock is held in do_gvl_timer. + * There is also no need to start a timer if we're the designated + * sigwait_th thread, otherwise we can deadlock with a thread + * in unblock_function_clear. */ - if (vm->gvl.timer != ruby_thread_from_native()) { + if (cur != vm->gvl.timer && cur != sigwait_th) { rb_native_mutex_lock(&vm->gvl.lock); if (!vm->gvl.timer) { rb_thread_wakeup_timer_thread(-1); -- cgit v1.2.3