CVS commit: src/sys/kern

["Taylor R Campbell" <riastradh%netbsd.org@localhost>]

Module Name:    src
Committed By:   riastradh
Date:           Thu Mar 10 12:21:25 UTC 2022

Modified Files:
        src/sys/kern: kern_lwp.c kern_synch.c

Log Message:
kern: Fix synchronization of clearing LP_RUNNING and lwp_free.

1. membar_sync is not necessary here -- only a store-release is
   required.

2. membar_consumer _before_ loading l->l_pflag is not enough; a
   load-acquire is required.

Actually it's not really clear to me why any barriers are needed, since
the store-release and load-acquire should be implied by releasing and
acquiring the lwp lock (and maybe we could spin with the lock instead
of reading l->l_pflag unlocked).  But maybe there's something subtle
about access to l->l_mutex that's not obvious here.


To generate a diff of this commit:
cvs rdiff -u -r1.246 -r1.247 src/sys/kern/kern_lwp.c
cvs rdiff -u -r1.349 -r1.350 src/sys/kern/kern_synch.c

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