Fix the last few cases that grab without busy or wired. This also happens to fix two cases of direct valid bit modification.
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Authored by jeff on Nov 30 2019, 8:40 AM.

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kib
markj
alc
dougm

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rS355313: Fix the last few cases that grab without busy or valid. The grab functions must

Summary

I have a number of small patches in my branch targeted at making the grab & busy usage more consistent. This enables tighter assertions that are necessary for lockless lookup & busy. In these particular cases the busy lock is acquired for free in page_alloc and we are only paying an extra atomic to release.

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rS FreeBSD src repository - subversion

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Event Timeline

jeff created this revision.Nov 30 2019, 8:40 AM

Harbormaster completed remote builds in B27856: Diff 65064.Nov 30 2019, 8:40 AM

jeff retitled this revision from Fix the last few cases that grab without busy or wired. This also happens to fix two cases of direct valid bit modification. to Fix the last few cases that grab without busy or wired. This also happensto fix two cases of direct valid bit modification..Nov 30 2019, 8:48 AM

jeff edited the summary of this revision. (Show Details)

jeff added reviewers: kib, markj, alc, dougm.

jeff mentioned this in D22611: Fix a few places that free a page from an object without busy held..Nov 30 2019, 9:12 AM

alc added inline comments.Nov 30 2019, 5:41 PM

sys/compat/cloudabi/cloudabi_vdso.c
63–64 ↗	(On Diff #65064)	Can't these two operations now be placed after the lock release? To be clear, I'm not concerned about the performance impact here, but rather that these are good examples when other people cut-and-paste elsewhere.

jeff added inline comments.Nov 30 2019, 9:17 PM

sys/compat/cloudabi/cloudabi_vdso.c
63–64 ↗	(On Diff #65064)	Yes you are right. Will fix.

jeff retitled this revision from Fix the last few cases that grab without busy or wired. This also happensto fix two cases of direct valid bit modification. to Fix the last few cases that grab without busy or wired. This also happens to fix two cases of direct valid bit modification..Dec 1 2019, 4:51 AM

Address review feedback.

Harbormaster completed remote builds in B27867: Diff 65087.Dec 1 2019, 4:52 AM

Drop object lock earlier.

Harbormaster completed remote builds in B27870: Diff 65094.Dec 1 2019, 11:07 AM

kib accepted this revision.Dec 1 2019, 8:52 PM

This revision is now accepted and ready to land.Dec 1 2019, 8:52 PM

markj accepted this revision.Dec 2 2019, 4:39 PM

alc accepted this revision.Dec 2 2019, 4:48 PM

Closed by commit rS355313: Fix the last few cases that grab without busy or valid. The grab functions must (authored by jeff). · Explain WhyDec 2 2019, 10:38 PM

This revision was automatically updated to reflect the committed changes.

jeff added a commit: rS355313: Fix the last few cases that grab without busy or valid. The grab functions must.

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