On Fri, Feb 23, 2018 at 04:58:12PM +0800, Boqun Feng wrote: > Hmm... think again, maybe I can combine case 1 with 3, and case 2 with > 4, because each of them could share the same find_usage_backwards(), and > find_usage_forwards() uses a usage_match_forwards() as follow for the > match function: > > static inline int usage_match_forwards(struct lock_list *entry, void > *bit) > { > enum lock_usage_bit ub = (enum lock_usage_bit)bit; > unsigned long mask; > unsigned long read_mask; > > /* mask out the read bit */ > ub &= ~1; > > mask = 1ULL << ub; > read_mask = 1ULL << (ub + 1); > > return (entry->class->usage_mask & mask) || // *-> L2 and L2 > is an irq-unsafe lock > ((entry->class->usage_mask & read_mask) && > !entry->is_rr); // N-> L2 and L2 is an irq-read-unsafe lock > } > > Got a bus to catch, I can explain this later, if you need ;-)
Right, that's about what I was thinking of. Clearly that needs a wee comment but it's much better.