On Sat, 6 Jul 2002, Andrew Gallatin wrote: > OK, current is really confusing me. When we are panic'ing and syncing > disks, how are we supposed to come back to the current thread which > caused the dump after we do an mi_switch() to allow an interrupt > thread to run? > > The alpha seems to get stuck running various sorts of kernel > processes, but it never comes back to the one that caused the dump. > > How is this supposed to work?
Accidentally at best. panic() cannot sleep and should not call mi_switch(), but sync() wants to do both. msleep() has a hack that prevents it from doing very much if (cold || panicstr). This works in most cases in FreeBSD-2, but has been rotting as the kernel became more complicated. Before KSEII, it was normal for synch() to hit a deadlock and panic recursively (with no sync() the second time). KSEII may have made things worse by putting a lot of code before the hack in msleep(). The cv_wait() family has the same (cold || panicstr) hack (including cloned (rotted) comments about doing something to give interrupts a chance) but no KSE checks before it. Bruce To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-current" in the body of the message
