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.
processes.
- Create a new data structure, the proclist_desc, which contains a
pointer to a proclist, and eventually, a pointer to the lock for that
proclist. Declare a static array of proclist_descs, proclists[],
consisting of allproc, deadproc, and zombproc.
(thus causing s_leader to become NULL) by storing the session ID separately
in the session structure. Export the session ID to userspace in the
eproc structure.
Submitted by Tom Proett <proett@nas.nasa.gov>.
thorpej