From bd117d62a6ac105bcb7062cef2aa141f50057787 Mon Sep 17 00:00:00 2001 From: Dmitry Kozlyuk Date: Fri, 30 Oct 2020 21:42:16 +0300 Subject: [PATCH] eal/windows: fix deadlock when setting alarm Windows alarms are both armed and executed from the interrupt thread. rte_eal_alarm_set() dispatched alarm-arming code to that thread and waited for its completion via a spinlock. However, if called from alarm callback (i.e. from the interrupt thread), this caused a deadlock, because arming could not be run until its dispatcher exits, but it could only exit after it finished waiting for arming to complete. Call arming code directly when running in the interrupt thread. Fixes: f4cbdbc7fbd2 ("eal/windows: implement alarm API") Reported-by: Pallavi Kadam Signed-off-by: Dmitry Kozlyuk Tested-by: Pallavi Kadam --- lib/librte_eal/windows/eal_alarm.c | 68 ++++++++++++++++++++---------- 1 file changed, 46 insertions(+), 22 deletions(-) diff --git a/lib/librte_eal/windows/eal_alarm.c b/lib/librte_eal/windows/eal_alarm.c index 3b262793a1..f5bf88715a 100644 --- a/lib/librte_eal/windows/eal_alarm.c +++ b/lib/librte_eal/windows/eal_alarm.c @@ -30,7 +30,7 @@ static LIST_HEAD(alarm_list, alarm_entry) alarm_list = LIST_HEAD_INITIALIZER(); static rte_spinlock_t alarm_lock = RTE_SPINLOCK_INITIALIZER; -static int intr_thread_exec(void (*func)(void *arg), void *arg); +static int intr_thread_exec_sync(void (*func)(void *arg), void *arg); static void alarm_remove_unsafe(struct alarm_entry *ap) @@ -57,6 +57,18 @@ alarm_callback(void *arg, DWORD low __rte_unused, DWORD high __rte_unused) rte_spinlock_unlock(&alarm_lock); } +static int +alarm_set(struct alarm_entry *entry, LARGE_INTEGER deadline) +{ + BOOL ret = SetWaitableTimer( + entry->timer, &deadline, 0, alarm_callback, entry, FALSE); + if (!ret) { + RTE_LOG_WIN32_ERR("SetWaitableTimer"); + return -1; + } + return 0; +} + struct alarm_task { struct alarm_entry *entry; LARGE_INTEGER deadline; @@ -64,14 +76,10 @@ struct alarm_task { }; static void -alarm_set(void *arg) +alarm_task_exec(void *arg) { struct alarm_task *task = arg; - - BOOL ret = SetWaitableTimer( - task->entry->timer, &task->deadline, - 0, alarm_callback, task->entry, FALSE); - task->ret = ret ? 0 : (-1); + task->ret = alarm_set(task->entry, task->deadline); } int @@ -80,14 +88,14 @@ rte_eal_alarm_set(uint64_t us, rte_eal_alarm_callback cb_fn, void *cb_arg) struct alarm_entry *ap; HANDLE timer; FILETIME ft; - struct alarm_task task; + LARGE_INTEGER deadline; int ret; /* Calculate deadline ASAP, unit of measure = 100ns. */ GetSystemTimePreciseAsFileTime(&ft); - task.deadline.LowPart = ft.dwLowDateTime; - task.deadline.HighPart = ft.dwHighDateTime; - task.deadline.QuadPart += 10 * us; + deadline.LowPart = ft.dwLowDateTime; + deadline.HighPart = ft.dwHighDateTime; + deadline.QuadPart += 10 * us; ap = calloc(1, sizeof(*ap)); if (ap == NULL) { @@ -106,21 +114,37 @@ rte_eal_alarm_set(uint64_t us, rte_eal_alarm_callback cb_fn, void *cb_arg) ap->timer = timer; ap->cb_fn = cb_fn; ap->cb_arg = cb_arg; - task.entry = ap; /* Waitable timer must be set in the same thread that will * do an alertable wait for the alarm to trigger, that is, - * in the interrupt thread. Setting can fail, so do it synchronously. + * in the interrupt thread. */ - ret = intr_thread_exec(alarm_set, &task); - if (ret < 0) { - RTE_LOG(ERR, EAL, "Cannot setup alarm in interrupt thread\n"); - goto fail; - } + if (rte_thread_is_intr()) { + /* Directly schedule callback execution. */ + ret = alarm_set(ap, deadline); + if (ret < 0) { + RTE_LOG(ERR, EAL, "Cannot setup alarm\n"); + goto fail; + } + } else { + /* Dispatch a task to set alarm into the interrupt thread. + * Execute it synchronously, because it can fail. + */ + struct alarm_task task = { + .entry = ap, + .deadline = deadline, + }; + + ret = intr_thread_exec_sync(alarm_task_exec, &task); + if (ret < 0) { + RTE_LOG(ERR, EAL, "Cannot setup alarm in interrupt thread\n"); + goto fail; + } - ret = task.ret; - if (ret < 0) - goto fail; + ret = task.ret; + if (ret < 0) + goto fail; + } rte_spinlock_lock(&alarm_lock); LIST_INSERT_HEAD(&alarm_list, ap, next); @@ -196,7 +220,7 @@ intr_thread_entry(void *arg) } static int -intr_thread_exec(void (*func)(void *arg), void *arg) +intr_thread_exec_sync(void (*func)(void *arg), void *arg) { struct intr_task task; int ret; -- 2.20.1