Hi, I finally got around to looking at what effect replacing pfind_locked() with pfind() has for the NFSv4 client and it is broken.
The problem is that the NFS code needs to call some variant of "pfind()" while holding a mutex lock. The current _pfind() code uses the pidhashtbl_locks, which are "sx" locks. There are a few ways to fix this: 1 - Create a custom version of _pfind() for the NFS client with the sx_X() calls removed, plus replace the locking of allproc_lock with locking of all the pidhashtbl_locks, so that the "sx" locks are acquired before the mutex. --> Not very efficient, but since it is only done once/sec, I can live with it. 2 - Similar to the above, but still lock the allproc_lock and use a loop of FOREACH_PROC_IN_SYSTEM(p) instead of a hash list for the pid in the custom pfind(). (I don't know if this would be preferable to locking all the pidhashtbl_locks for other users of pfind()?) 3 - Convert the pidhashtbl_locks to mutexes. Then the NFS client doesn't need to acquire any proc related locks and it just works. I can't see anywhere that "sleeps" while holding the pidhashtbl_locks, so I think they can be converted, although I haven't tried it yet? >From my perspective, #3 seems the better solution. What do others think? rick _______________________________________________ freebsd-current@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"