proclist_mutex and proclist_lock into a single adaptive mutex (proc_lock).
Implications:
- Inspecting process state requires thread context, so signals can no longer
be sent from a hardware interrupt handler. Signal activity must be
deferred to a soft interrupt or kthread.
- As the proc state locking is simplified, it's now safe to take exit()
and wait() out from under kernel_lock.
- The system spends less time at IPL_SCHED, and there is less lock activity.
The general trend is to remove it from all kernel interfaces and
this is a start. In case the calling lwp is desired, curlwp should
be used.
quick consensus on tech-kern
need to understand the locking around that field. Instead of setting
B_ERROR, set b_error instead. b_error is 'owned' by whoever completes
the I/O request.
in 1.153 revision, where ltsleep() was replaced with condvar.
Problem found and fix provided by David A. Holland, PR/36610.
Actually, relock is not needed here, and mutex would be unlocked
only on nfs_sigintr() fail case.
- IO_SYNC: don't bother to flush dirty pages before copying data from
user buffer.
- IO_APPEND: don't invalidate pages blindly. PR/28472 from Brian Marcotte.
- use vmspace rather than proc or lwp where appropriate.
the latter is more natural to specify an address space.
(and less likely to be abused for random purposes.)
- fix a swdmover race.
shortcut to the process of the passed lwp paniced the kernel since lwp
could/can be passwd as NULL in VOP_WRITE().
This was happening when ktracing to NFS. The function ktrwrite() set the
uio_lwp to NULL and then calls VOP_WRITE() with this argument. nfs_write()
then accessed lwp *l->l_proc wich paniced.
Thanks to David Laight for his help on tracking it down.
of curproc (where uio->uio_procp should be used?). Don't do this
for nfs_commit(), because yamt says it is possibly wrong.
2. nfs_doio() does not use struct proc; remove it and the code to compute it.
3. use copyin_proc() and copyout_proc() instead of copyin() and copyout().
4. check return of copyout_proc(). and mark return from copyin_proc() XXX
5. Eliminate check p == curproc assertion check from nfs_write;
nfs_read does not have it and we might be called in a different
process context anyway (PR 20138).
