On Thu, Mar 22, 2018 at 05:50:57PM +1100, Bruce Evans wrote: > On Wed, 21 Mar 2018, Warner Losh wrote: > > > On Wed, Mar 21, 2018 at 2:27 PM, Konstantin Belousov <kostik...@gmail.com> > > wrote: > >> ... > >> Are you saying that fast interrupt handlers call shutdown_nice() ? This > >> is the quite serious bug on its own. To fix it, shutdown_nice() should > >> use a fast taskqueue to schedule the task which would lock the process > >> and send the signal. > > > > Is there some way we know we're in a fast interrupt handler? If so, it > > should be simple to fix. If not, then there's an API change ahead of us... > > There is a td_intr_nesting_level flag that might work. (I invented this, > but don't like its current use.) But why do we need to know this ? We can always schedule a task in the fast taskqueue if init is present and can be scheduled.
> > > But bde is right: the system has to be in good enough shape to cope. I > > wonder if we should put that coping into kdb_reboot() instead. It's only an > > issue for <CR> TILDE ^R, which is a fairly edge case. > > shutdown_nice() is also called directly from syscons and vt for the reboot, > halt and poweroff keys. This happens in normal interrupt handler context, > so there is only a problem when init is not running. diff --git a/sys/kern/kern_shutdown.c b/sys/kern/kern_shutdown.c index e5ea9644ad3..e7c6d4c92b2 100644 --- a/sys/kern/kern_shutdown.c +++ b/sys/kern/kern_shutdown.c @@ -72,6 +72,7 @@ __FBSDID("$FreeBSD$"); #include <sys/smp.h> #include <sys/sysctl.h> #include <sys/sysproto.h> +#include <sys/taskqueue.h> #include <sys/vnode.h> #include <sys/watchdog.h> @@ -276,6 +277,28 @@ sys_reboot(struct thread *td, struct reboot_args *uap) return (error); } +static void +shutdown_nice_task_fn(void *arg, int pending __unused) +{ + int howto; + + howto = (uintptr_t)arg; + /* Send a signal to init(8) and have it shutdown the world. */ + PROC_LOCK(initproc); + if (howto & RB_POWEROFF) + kern_psignal(initproc, SIGUSR2); + else if (howto & RB_POWERCYCLE) + kern_psignal(initproc, SIGWINCH); + else if (howto & RB_HALT) + kern_psignal(initproc, SIGUSR1); + else + kern_psignal(initproc, SIGINT); + PROC_UNLOCK(initproc); +} + +static struct task shutdown_nice_task = TASK_INITIALIZER(0, + &shutdown_nice_task_fn, NULL); + /* * Called by events that want to shut down.. e.g <CTL><ALT><DEL> on a PC */ @@ -283,20 +306,14 @@ void shutdown_nice(int howto) { - if (initproc != NULL) { - /* Send a signal to init(8) and have it shutdown the world. */ - PROC_LOCK(initproc); - if (howto & RB_POWEROFF) - kern_psignal(initproc, SIGUSR2); - else if (howto & RB_POWERCYCLE) - kern_psignal(initproc, SIGWINCH); - else if (howto & RB_HALT) - kern_psignal(initproc, SIGUSR1); - else - kern_psignal(initproc, SIGINT); - PROC_UNLOCK(initproc); + if (initproc != NULL && !SCHEDULER_STOPPED()) { + shutdown_nice_task.ta_context = (void *)(uintptr_t)howto; + taskqueue_enqueue(taskqueue_fast, &shutdown_nice_task); } else { - /* No init(8) running, so simply reboot. */ + /* + * No init(8) running, or scheduler would not allow it + * to run, so simply reboot. + */ kern_reboot(howto | RB_NOSYNC); } } _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"