CVS commit: src/sys/dev/sysmon

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

Module Name:    src
Committed By:   riastradh
Date:           Fri Dec 31 14:30:04 UTC 2021

Modified Files:
        src/sys/dev/sysmon: sysmon_envsys.c sysmon_envsys_events.c sysmonvar.h

Log Message:
sysmon(9): Fix callout/thread synchronization.

Callout may ONLY take sme_work_mtx, at IPL_SOFTCLOCK; MUST NOT touch
sme_mtx at IPL_NONE.  All state the callout needs is serialized by
sme_work_mtx now:

- calls to sme_schedule_callout
- calls to sme_schedule_halt
- struct sysmon_envsys::sme_events_timeout
- struct sysmon_envsys::sme_events_list
- struct sysmon_envsys::sme_callout_state
- struct envsys_data::flags
  => yes, this is a little silly -- used for ENVSYS_FNEED_REFRESH
  => should maybe separate the static driver-defined features from
     the state flags needed by sysmon_envsys but not important now

Sleeping under sme_work_mtx (except on other adaptive locks at
IPL_SOFTCLOCK) is forbidden.  Calling out to the driver under
sme_work_mtx is forbidden.

This should properly fix:

https://mail-index.netbsd.org/tech-kern/2015/10/14/msg019511.html
PR kern/56592


To generate a diff of this commit:
cvs rdiff -u -r1.149 -r1.150 src/sys/dev/sysmon/sysmon_envsys.c
cvs rdiff -u -r1.122 -r1.123 src/sys/dev/sysmon/sysmon_envsys_events.c
cvs rdiff -u -r1.51 -r1.52 src/sys/dev/sysmon/sysmonvar.h

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