On 03/07/2019 04:07, Patrick Farrell wrote: > Recursively read locking is generally unsafe, that’s why lockdep > complains about it. The common RW lock primitives are queued in > their implementation, meaning this recursive read lock sequence: > P1 - read (gets lock) > P2 - write > P1 - read > > Results not in a successful read lock, but P1 blocking behind P2, > which is blocked behind P1. > Readers are not allowed to jump past waiting writers. OK thanks that makes sense. I did not know about that last part. Its a kind of a lock fairness I did not know we have. So I guess I'll keep my two locks than. The write_locker is the SLOW path for me anyway, right? [if we are already at the subject, Do mutexes have the same lock fairness as above? Do the write_lock side of rw_sem have same fairness? Something I never figured out] Thanks Boaz > > - Patrick
