On Thu, Mar 22, 2018 at 04:53:22AM +1100, Bruce Evans wrote: > Serial console drivers with fast interrupt handlers have much more > broken locking for ddb special keys. It is invalid to either drop locks > or call the "any" function from a fast interrupt handler, but buggy > serial console drivers calls kbd_alt_break(), and that now calls > shutdown_nice() and other functions that cannot be called from a fast > interrupt handler. ddb keys supply most of the shutdown_nice() > functionality for serial consoles, and there are no escape sequence to > get this without ddb or maybe another debugger, so these bugs don't > affect most users. > > Handling this correctly requires much the same fix as an unsafe signal > handler, and fixes have much the same problems -- not much more than > setting a flag is safe, and the flag might never be looked at if the > system is in a bad state. However, if a nice shutdown is possible then > the sytem must be in a good enough state to poll for flags.
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. _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
