- Introduce lock classes and lock objects. Each lock class specifies a
name and set of flags (or properties) shared by all locks of a given
type. Currently there are three lock classes: spin mutexes, sleep
mutexes, and sx locks. A lock object specifies properties of an
additional lock along with a lock name and all of the extra stuff needed
to make witness work with a given lock. This abstract lock stuff is
defined in sys/lock.h. The lockmgr constants, types, and prototypes have
been moved to sys/lockmgr.h. For temporary backwards compatability,
sys/lock.h includes sys/lockmgr.h.
- Replace proc->p_spinlocks with a per-CPU list, PCPU(spinlocks), of spin
locks held. By making this per-cpu, we do not have to jump through
magic hoops to deal with sched_lock changing ownership during context
switches.
- Replace proc->p_heldmtx, formerly a list of held sleep mutexes, with
proc->p_sleeplocks, which is a list of held sleep locks including sleep
mutexes and sx locks.
- Add helper macros for logging lock events via the KTR_LOCK KTR logging
level so that the log messages are consistent.
- Add some new flags that can be passed to mtx_init():
- MTX_NOWITNESS - specifies that this lock should be ignored by witness.
This is used for the mutex that blocks a sx lock for example.
- MTX_QUIET - this is not new, but you can pass this to mtx_init() now
and no events will be logged for this lock, so that one doesn't have
to change all the individual mtx_lock/unlock() operations.
- All lock objects maintain an initialized flag. Use this flag to export
a mtx_initialized() macro that can be safely called from drivers. Also,
we on longer walk the all_mtx list if MUTEX_DEBUG is defined as witness
performs the corresponding checks using the initialized flag.
- The lock order reversal messages have been improved to output slightly
more accurate file and line numbers.
INVARIANTS case, define the actual KASSERT() in _SX_ASSERT_[SX]LOCKED
macros that are used in the sx code itself and convert the
SX_ASSERT_[SX]LOCKED macros to simple wrappers that grab the mutex for the
duration of the check.
- Add sx_xholder member to sx struct which is used for INVARIANTS-enabled
assertions. It indicates the thread that presently owns the xlock.
- Add some assertions to the sx lock code that will detect the fatal
API abuse:
xlock --> xlock
xlock --> slock
which now works thanks to sx_xholder.
Notice that the remaining two problematic cases:
slock --> xlock
slock --> slock (a little less problematic, but still recursion)
will need to be handled by witness eventually, as they are more
involved.
Reviewed by: jhb, jake, jasone
