The problem was due to an interaction between the doomed unmounts done by
amd and getnewvnode.
I convinced myself that it's ok for getnewvnode() to do a sleeping vfs_busy().
Tested with multiple builds running while another process attempted to unmount
/usr once a second.
too. Remove some needless code duplication by adding a "drain" argument
to the ACQUIRE() macro (compiler can [and does] optimize the constant
conditional).
free a PV page if the PV entry was associated with the kernel pmap,
since the kernel pmap is locked, and freeing the page will execute
a code path which will attempt to lock it again, resulting in deadlock.
No real loss, since the next time a PV entry is freed, the page will
be freed, too.
locking primitive directly to lock it, since those will never attempt
to call printf() to display debugging information (and thus deadlock
on recursion into the kprintf_slock).
- Now compatible with MULTIPROCESSOR (requires other changes not yet
committed, but which will be later today).
- In addition to tracking simple locks, track exclusive spin locks.
- Count spin locks like we do sleep locks (in the cpu_info for this
CPU).
- Lock debug lists are now TAILQs, so as to make the locking order
more obvious when dumping the list.
Also, some suggestions from Bill Sommerfeld:
- SIMPLELOCK_LOCKED and SIMPLELOCK_UNLOCKED constants, which may be
defined in <machine/lock.h> (default to 1 and 0, respectively). This
makes it easier to support architectures which use test-and-clear
rather than test-and-set.
- Add __attribute__((__aligned__)) to the `lock_data' member of the
simplelock structure. This makes it easier to support architectures
which can only perform atomic operations on very-well-aligned memory
locations. NOTE: This changes the size of struct simplelock, and
will cause a version bump.
once for ipv6. This patch makes the ipv6 case pass NULLs in for fast
and slow timeouts iff defined(INET) and passes in the right function
if !defined(INET).
Reveiwed by itojun@iijlab.net.
first in line for the specified identifier. For use in places where
you don't want a Thundering Herd.
While here, add an optimization to wakeup() suggested by Ross Harvey.
- 'struct fbsoftc' created, which points to a 'struct fbinfo'
- 'struct fbinfo' for each device is allocated with fballoc()
This means:
- Console device doesn't get different 'struct fbinfo' at attach
- Console device doesn't get initialized twice
- Color rcons now works
- The current Xserver MUST BE REBUILT.
calls to reflect this. Also, block statclock rather than softclock during
in the proclist locking functions, to address a problem reported on
current-users by Sean Doran.
write lock when doing PID allocation, and during the process exit path.
Use a read lock every where else, including within schedcpu() (interrupt
context). Note that holding the write lock implies blocking schedcpu()
from running (blocks softclock).
PID allocation is now MP-safe.
Note this actually fixes a bug on single processor systems that was probably
extremely difficult to tickle; it was possible that schedcpu() would run
off a bad pointer if the right clock interrupt happened to come in the
middle of a LIST_INSERT_HEAD() or LIST_REMOVE() to/from allproc.
and PID allocation MP-safe. A new process state is added: SDEAD. This
state indicates that a process is dead, but not yet a zombie (has not
yet been processed by the process reaper).
SDEAD processes exist on both the zombproc list (via p_list) and deadproc
(via p_hash; the proc has been removed from the pidhash earlier in the exit
path). When the reaper deals with a process, it changes the state to
SZOMB, so that wait4 can process it.
Add a P_ZOMBIE() macro, which treats a proc in SZOMB or SDEAD as a zombie,
and update various parts of the kernel to reflect the new state.
by default. The X11 distribution included in our last release already
supports it and the wsmouse protocol can be used for any of the above
and for USB mice.
body of reaper(), right before the call to uvm_exit(). cpu_wait() must
be done before uvm_exit() because the resources it frees might be located
in the PCB.
