Messages in this thread | | | Date | Tue, 16 Aug 2022 15:48:00 +0800 | From | Herbert Xu <> | Subject | Re: [PATCH] workqueue: Fix memory ordering race in queue_work*() |
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On Tue, Aug 16, 2022 at 03:28:50PM +0900, Hector Martin wrote: > > This is the same reason I argued queue_work() itself needs to have a > similar guarantee, even when it doesn't queue work (and I updated the > doc to match). If test_and_set_bit() is used in this kind of context > often in the kernel, clearly the current implementation/doc clashes with > that.
Kernel code all over the place rely on the fact that test_and_set_bit provides a memory barrier. So this bug that you've discovered is not at all isolated to the workqeueue system. It'll break the kernel in lots of places in exactly the same way.
> As I said, I don't have any particular beef in this fight, but this is > horribly broken on M1/2 right now, so I'll send a patch to change the > bitops instead and you all can fight it out over which way is correct :)
Please do.
Thanks, -- Email: Herbert Xu <herbert@gondor.apana.org.au> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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