Dennis Clarke <dclarke_at_blastwave.org> wrote on Date: Tue, 20 May 2025 02:33:58 UTC:
> Just an odd message to see on the console : > > # witness_lock_list_get: witness exhausted > > Looking at https://cgit.freebsd.org/src/tree/sys/kern/subr_witness.c it > seems that the comment at line 370 is very clear : > > /* > * If set to 0, lock order checking is disabled. If set to -1, > * witness is completely disabled. Otherwise witness performs full > * lock order checking for all locks. At runtime, lock order checking > * may be toggled. However, witness cannot be reenabled once it is > * completely disabled. > */ > static int witness_watch = 1; > > So I wonder how I managed to get that message "witness exhausted" ? > > At line 2203 I see : > > static struct lock_list_entry * > witness_lock_list_get(void) > { > struct lock_list_entry *lle; > > if (witness_watch == -1) > return (NULL); > mtx_lock_spin(&w_mtx); > lle = w_lock_list_free; > if (lle == NULL) { Looks to me like "out of required resources, cannot continue with the mode of use" code: an empty free list so no node is available to put to use to continue with the witness handling. > witness_watch = -1; > mtx_unlock_spin(&w_mtx); > printf("%s: witness exhausted\n", __func__); > return (NULL); > } > w_lock_list_free = lle->ll_next; > mtx_unlock_spin(&w_mtx); > bzero(lle, sizeof(*lle)); > return (lle); > } > > Where it seems that indeed witness_watch has been flipped to -1 and that > functionality is now gone? Until the next boot, anyway. === Mark Millard marklmi at yahoo.com
