Mark more nodes as CTLFLAG_MPSAFE or CTLFLAG_NEEDGIANT (M of N)

[kaktus]

Summary

r357614 added CTLFLAG_NEEDGIANT to make it easier to find nodes that are still not MPSAFE (or already are but aren’t properly marked). Use it in preparation for a general review of all nodes.
This is non-functional change that adds annotations to SYSCTL_NODE and SYSCTL_PROC nodes using one of the soon-to-be-required flags.
Mark all low hanging fruits as MPSAFE.

You’re asked for a review based on src/MAINTAINERS entry.

[markj]

sys/dev/ath/ah_osdep.c

241 ↗

(On Diff #68138)

I don't think Giant helps this function. ath_hal_reg_(read|write)() don't acquire it, so it is not synchronizing anything.

sys/dev/ath/ath_rate/sample/sample.c

1376 ↗

(On Diff #68138)

Ditto. There are no references to Giant in ath(9) so I am quite sure these can be marked MPSAFE.

sys/net80211/ieee80211_hwmp.c

196 ↗

(On Diff #68138)

None of these variables have accesses synchronized with Giant, and ieee80211_sysctl_msecs_ticks() does not require Giant.

[kaktus]

Address comments.

[kaktus]

Upload the correct patch.

[markj]

sys/dev/ath/ath_rate/sample/sample.c

1376 ↗

(On Diff #68138)

So shouldn't we explicitly add CTLFLAG_MPSAFE?

[kaktus]

sys/dev/ath/ath_rate/sample/sample.c

1376 ↗

(On Diff #68138)

We absolutely should.

[kaktus]

Update diff.

[markj]

I am fairly confident that none of the sysctls in this review require Giant, if only because Giant is not referenced at all in ath(9) or the ieee80211 stack. It is just a matter of going through and convincing oneself in each case. I did a few more, but if you prefer to just commit and revisit later, it is ok with me.

sys/net80211/ieee80211_freebsd.c

262 ↗

(On Diff #68596)

ieee80211_sysctl_inact() does a pure conversion, there is no need for Giant.

sys/net80211/ieee80211_hwmp.c

218 ↗

(On Diff #68596)

This does not need Giant, the proc is just doing a ms->ticks unit conversion.

sys/net80211/ieee80211_mesh.c

134 ↗

(On Diff #68596)

None of these need Giant. They are field accessors that just convert to a ticks value.

[kaktus]

That is the plan - document current state now, review and fix what have to be fixed later. The flag itself doesn't change anything, it's just a more explicit way of showing that the handler may be not-MPSAFE.