CVS commit: [netbsd-6-0] src/sys/kern

["Soren Jacobsen" <snj%netbsd.org@localhost>]

Module Name:    src
Committed By:   snj
Date:           Thu Jul 14 06:43:35 UTC 2016

Modified Files:
        src/sys/kern [netbsd-6-0]: kern_softint.c

Log Message:
Pull up following revision(s) (requested by knakahara in ticket #1356):
        sys/kern/kern_softint.c: revision 1.42
fix the following softint parallel operation problem.
(0) softint handler "handler A" is established
(1) CPU#X does softint_schedule() for "handler A"
    - the softhand_t is set SOFTINT_PENDING flag
    - the softhand_t is NOT set SOFTINT_ACTIVE flag yet
(2) CPU#X begins other H/W interrupt processing
(3) CPU#Y does softint_disestablish() for "handler A"
    - waits until softhand_t's SOFTINT_ACTIVE of all CPUs is clear
    - the softhand_t is set not SOFTINT_ACTIVE but SOFTINT_PENDING,
      so CPU#Y does not wait
    - unset the function of "handler A"
(4) CPU#X does softint_execute()
    - the function of "handler A" is already clear, so panic


To generate a diff of this commit:
cvs rdiff -u -r1.38.14.1 -r1.38.14.2 src/sys/kern/kern_softint.c

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