kern: keep track of the writer when debugging locks

* configfrag.ac (MACH_LDEBUG): Adjust comment, we use it to sanity
check all locks now.
* kern/lock.c (lock_write): Keep track of the writer thread.
(lock_done): Clear writer.
(lock_read_to_write): Keep track of the writer thread.
(lock_write_to_read): Assert that the current thread holds the lock.
Clear writer.
(lock_try_write): Keep track of the writer thread.
(lock_try_read_to_write): Likewise.
(lock_set_recursive): Assert that the current thread holds the lock.
* kern/lock.h (struct lock): New field `writer'.
(have_read_lock, have_write_lock, have_lock): New macros that can be
used to assert that the current thread holds the given lock.  If
MACH_LDEBUG is not set, they evaluate to true.

0 files changed, 0 insertions, 0 deletions