From 97538e813f8d41d7091aa6d1ffd15466117b26b1 Mon Sep 17 00:00:00 2001 From: normal Date: Thu, 26 Jul 2018 08:30:10 +0000 Subject: cont.c (ec_switch): prevent delayed/missed trap interrupt race timer-thread may set trap interrupt with rb_threadptr_check_signal at any time independent of GVL. This means timer-thread may set the trap interrupt flag on the previous execution context; causing the flag to be unnoticed until a future ec switch (or lost completely if the ec is done). Note: I avoid relying on th->interrupt_lock here and use atomics because we won't be able to rely on it for proposed lazy timer-thread [Misc #14937]. This regression affects Ruby 2.5 as it was introduced by moving interrupt_flag to `ec' which is an unstable pointer. Ruby <= 2.4 was unaffected because vm->main_thread->interrupt_flag never changed. [ruby-core:88119] [Bug #14939] git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@64062 b2dd03c8-39d4-4d8f-98ff-823fe69b080e --- cont.c | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'cont.c') diff --git a/cont.c b/cont.c index 082b47dae2..1f82a7944e 100644 --- a/cont.c +++ b/cont.c @@ -262,7 +262,17 @@ static inline void ec_switch(rb_thread_t *th, rb_fiber_t *fib) { rb_execution_context_t *ec = &fib->cont.saved_ec; + ruby_current_execution_context_ptr = th->ec = ec; + + /* + * timer-thread may set trap interrupt on previous th->ec at any time; + * ensure we do not delay (or lose) the trap interrupt handling. + */ + if (th->vm->main_thread == th && rb_signal_buff_size() > 0) { + RUBY_VM_SET_TRAP_INTERRUPT(ec); + } + VM_ASSERT(ec->fiber_ptr->cont.self == 0 || ec->vm_stack != NULL); } -- cgit v1.2.3