On Mon, May 10, 2010 at 12:27:40AM +0200, Attilio Rao wrote: > 2010/5/9 Marius Strobl <mar...@alchemy.franken.de>: > > On Mon, Apr 19, 2010 at 11:27:54PM +0000, Attilio Rao wrote: > >> Author: attilio > >> Date: Mon Apr 19 23:27:54 2010 > >> New Revision: 206878 > >> URL: http://svn.freebsd.org/changeset/base/206878 > >> > >> Log: > >> ?? Fix a deadlock in the shutdown code: > >> ?? When performing a smp_rendezvous() or more likely, on amd64 and i386, > >> ?? a smp_tlb_shootdown() the caller will end up with the smp_ipi_mtx > >> ?? spinlock held, busy-waiting for other CPUs to acknowledge the operation. > >> ?? As long as CPUs are suspended (via cpu_reset()) between the active mask > >> ?? read and IPI sending there can be a deadlock where the caller will wait > >> ?? forever for a dead CPU to acknowledge the operation. > >> ?? Please note that on CPU0 that is going to be someway heavier because of > >> ?? the spinlocks being disabled earlier than quitting the machine. > >> > >> ?? Fix this bug by calling cpu_reset() with the smp_ipi_mtx held. > >> ?? Note that it is very likely that a saner offline/online CPUs mechanism > >> ?? will help heavilly in fixing similar cases as it is likely more bugs > >> ?? of this type may arise in the future. > >> > > > > This change causes a hang for me when running an SMP kernel on an > > UP machine or an MP machine with SMP disabled as in these cases > > smp_ipi_mtx isn't initialized (see mp_start()). The below patch > > fixes this for me. > > Marius, > thanks a lot for reporting this. > However, I think that a better fix is to always initialize the mutex. > Do you think the following patch is fine for you?: > http://www.freebsd.org/~attilio/smpipi_fixup.diff >
Yes, this fixes it as well. Marius _______________________________________________ svn-src-head@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
