BTW, we have a quite strange situation with spin locks in console output path. cnputs_mtx is marked as MTX_NOWITNESS, supposedly because cnputs (printf) can be called in any locking context (even during normal operation). But there are a number of console-specific locks (scrlock, uart_hwmtx, "syscons video lock") which are acquired under cnputs_mtx, but which are *not* marked as MTX_NOWITNESS. More, they are specified in the witness order_lists as if we certainly know a correct order for them. I think that the msgbuf mutex also deserves mentioning in this context.
I think that all of these spin locks should be marked as MTX_NOWITNESS (as long as they stay normal spinlocks), because printf(9) should be usable wherever I stick it in the code. P.S. The above only matters for WITNESS and !WITNESS_SKIPSPIN and I am not sure if this combination really matters. -- Andriy Gapon _______________________________________________ freebsd-current@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"
