Messages in this thread | | | From | Rusty Russell <> | Subject | Re: [PATCH] Re: today's futex changes | Date | Tue, 09 Sep 2003 11:37:08 +1000 |
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In message <Pine.LNX.4.44.0309081746180.7008-100000@localhost.localdomain> you write: > Most of it (the futex_wait tweaks) looked fine to me - > though I look forward to the first report of that BUG().
Me too. But at least we'll *get* a report if someone does spurious wakeups.
> Part 2, requiring VM_WRITE and removing the comment on VM_MAYSHARE, > seems a regression to me. Perhaps I misinterpreted Linus' action in > taking Jamie's patch: I took that to mean he relented a little on his > hardline position about VM_SHARED, and now accepts that in this context > VM_MAYSHARE is more appropriate (easier to document). I know I argued > that readonly futices are pointless, but I thought Jamie gave a good > picture of how a readonly view could still be used. I'd rather that > part were a separate patch, so Linus can merge or not as he wishes.
Sure, I jumboed them together for feedback from you guys.
All users I am currently aware of won't care either way. Current test-5 is:
Sees Changes Sees FUTEX_WAKE from another MAP_SHARED from another MAP_SHARED
MAP_PRIVATE read-only: Y N MAP_PRIVATE read-write: Y* N MAP_SHARED read-only: Y Y MAP_SHARED read-write: Y Y
[* Only until page is written to, after which COW splits them ]
Previously, the FUTEX_WAKE column was identical to the first column. Now, IMHO, this new semantic is more sensible, but I don't really mind.
But I don't recall anything about believable use of RO futexes: Jamie?
Cheers, Rusty. -- Anyone who quotes me in their sig is an idiot. -- Rusty Russell. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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