From 5952b775bf1b164feabb439630faf86fcfce082d Mon Sep 17 00:00:00 2001 From: Taylor R Campbell Date: Fri, 25 Mar 2022 20:45:26 +0000 Subject: [PATCH] sysmon(9): Allow task queue to issue barrier. Treat it as a no-op. Fixes crash on shutdown with thinkpad(4): 1. power switch schedules sysmon task to shut system down, 2. sysmon task calls config_detach_all to detach with DETACH_SHUTDOWN, 3. autoconf detaches every device with DVF_DETACH_SHUTDOWN, 4. thinkpad_detach calls sysmon_task_queue_barrier from task queue (via acpi_deregister_notify -> AcpiOsWaitEventsComplete). This is kind of sleazy... XXX and I'm not sure it's correct (Not sure why thinkpad(4) sets DVF_DETACH_SHUTDOWN, but this general problem might occur in other drivers too.) --- sys/dev/sysmon/sysmon_taskq.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/sys/dev/sysmon/sysmon_taskq.c b/sys/dev/sysmon/sysmon_taskq.c index 559987ddc2a1..2d5bd18ff673 100644 --- a/sys/dev/sysmon/sysmon_taskq.c +++ b/sys/dev/sysmon/sysmon_taskq.c @@ -286,7 +286,9 @@ sysmon_task_queue_barrier(u_int pri) (void)RUN_ONCE(&once_tq, tq_preinit); KASSERT(sysmon_task_queue_lwp); - KASSERT(curlwp != sysmon_task_queue_lwp); + + if (curlwp == sysmon_task_queue_lwp) + return; mutex_init(&bar.lock, MUTEX_DEFAULT, IPL_NONE); cv_init(&bar.cv, "sysmontq");