Messages in this thread | | | Date | Mon, 3 Feb 2020 16:02:28 +0000 | From | Will Deacon <> | Subject | Re: Confused about hlist_unhashed_lockless() |
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On Mon, Feb 03, 2020 at 07:58:39AM -0800, Paul E. McKenney wrote: > On Mon, Feb 03, 2020 at 03:45:54PM +0000, David Laight wrote: > > From: Eric Dumazet > > > Sent: 31 January 2020 18:53 > > > > > > On Fri, Jan 31, 2020 at 10:48 AM Eric Dumazet <edumazet@google.com> wrote: > > > > > > > > > > > This is nice, now with have data_race() > > > > > > > > Remember these patches were sent 2 months ago, at a time we were > > > > trying to sort out things. > > > > > > > > data_race() was merged a few days ago. > > > > > > Well, actually data_race() is not there yet anyway. > > > > Shouldn't it be NO_DATA_RACE() ?? > > No, because you use data_race() when there really are data races, but you > want KCSAN to ignore them. For example, diagnostic code that doesn't > participate in the actual concurrency design and that doesn't run all > that often might use data_race(). For another example, if a developer > knew that data races existed, but that the compiler could not reasonably > do anything untoward with those data races, that developer might well > choose to use data_race() instead of READ_ONCE(). Especially if the > access in question was on a fastpath where helpful compiler optimizations > would be prohibited by use of READ_ONCE().
Yes, and in this particular case I think we can remove some WRITE_ONCE()s from the non-RCU hlist code too (similarly for hlist_nulls).
Will
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