CVS commit: src/sys

["Andrew Doran" <ad%netbsd.org@localhost>]

Module Name:    src
Committed By:   ad
Date:           Fri Dec  6 21:36:11 UTC 2019

Modified Files:
        src/sys/kern: kern_exec.c kern_exit.c kern_idle.c kern_lwp.c kern_sig.c
            kern_sleepq.c kern_softint.c kern_synch.c
        src/sys/sys: sched.h

Log Message:
Make it possible to call mi_switch() and immediately switch to another CPU.
This seems to take about 3us on my Intel system.  Two changes required:

- Have the caller to mi_switch() be responsible for calling spc_lock().
- Avoid using l->l_cpu in mi_switch().

While here:

- Add a couple of calls to membar_enter()
- Have the idle LWP set itself to LSIDL, to match softint_thread().
- Remove unused return value from mi_switch().


To generate a diff of this commit:
cvs rdiff -u -r1.484 -r1.485 src/sys/kern/kern_exec.c
cvs rdiff -u -r1.277 -r1.278 src/sys/kern/kern_exit.c
cvs rdiff -u -r1.27 -r1.28 src/sys/kern/kern_idle.c
cvs rdiff -u -r1.216 -r1.217 src/sys/kern/kern_lwp.c
cvs rdiff -u -r1.380 -r1.381 src/sys/kern/kern_sig.c
cvs rdiff -u -r1.53 -r1.54 src/sys/kern/kern_sleepq.c
cvs rdiff -u -r1.54 -r1.55 src/sys/kern/kern_softint.c
cvs rdiff -u -r1.328 -r1.329 src/sys/kern/kern_synch.c
cvs rdiff -u -r1.79 -r1.80 src/sys/sys/sched.h

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.