From e0df43fedfe4ae990f4b9ef59c79fdc9b57bce45 Mon Sep 17 00:00:00 2001 From: Sean McBride Date: Tue, 14 Jul 2020 14:14:38 -0400 Subject: [PATCH] docs: added comments to SIGALRM --- runtime/src/software_interrupt.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-) diff --git a/runtime/src/software_interrupt.c b/runtime/src/software_interrupt.c index 2370d4e..fc4c249 100644 --- a/runtime/src/software_interrupt.c +++ b/runtime/src/software_interrupt.c @@ -72,9 +72,9 @@ software_interrupt_handle_signals(int signal_type, siginfo_t *signal_info, void if (signal_info->si_code == SI_KERNEL) { /* Signal was sent directly by the kernel, so forward to other threads */ for (int i = 0; i < runtime_total_worker_processors; i++) { - if (pthread_self() != runtime_worker_threads[i]) { - pthread_kill(runtime_worker_threads[i], SIGALRM); - } + if (pthread_self() == runtime_worker_threads[i]) continue; + + pthread_kill(runtime_worker_threads[i], SIGALRM); } } else { /* Signal forwarded from another thread. Just confirm it resulted from pthread_kill */ @@ -90,8 +90,24 @@ software_interrupt_handle_signals(int signal_type, siginfo_t *signal_info, void /* Do not allow more than one layer of preemption */ if (worker_thread_next_context) return; - /* if the current sandbox is NULL or in a RETURNED state, nothing to preempt, so just return */ + /* + * if a SIGALRM fires while the worker thread is between sandboxes, executing libuv, completion queue + * cleanup, etc. current_sandbox might be NULL. In this case, we should just allow return to allow the + * worker thread to run the main loop until it loads a new sandbox. + * + * TODO: Consider if this should be an invarient and the worker thread should disable software + * interrupts when doing this work. + */ if (!current_sandbox) return; + + /* + * if a SIGALRM fires while the worker thread executing cleanup of a sandbox, it might be in a RETURNED + * state. In this case, we should just allow return to allow the sandbox to complete cleanup, as it is + * about to switch to a new sandbox. + * + * TODO: Consider if this should be an invarient and the worker thread should disable software + * interrupts when doing this work. + */ if (current_sandbox->state == SANDBOX_RETURNED) return; /* Preempt */