Messages in this thread | | | From | David Howells <> | Subject | Re: [PATCH] KEYS: fix race between updating and finding negative key | Date | Tue, 19 Sep 2017 17:22:28 +0100 |
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Eric Biggers <ebiggers3@gmail.com> wrote:
> Fix the bug by moving ->reject_error out of the union with ->payload, > then using nonzero ->reject_error to mean that the key is negative. > > This eliminates the need for KEY_FLAG_NEGATIVE, which we remove as well > so that we don't have to handle memory ordering between > KEY_FLAG_NEGATIVE and ->reject_error. We *do* still need to handle > memory ordering between KEY_FLAG_INSTANTIATED and ->reject_error, but > that was needed before (and for KEY_FLAG_NEGATIVE as well --- though it > wasn't done correctly, which was another bug).
Hmmm... My only objection is that it extends struct key still further, but you do have a point.
If we're going to do this, can we eliminate KEY_FLAG_INSTANTIATED also and make ->reject_error into ->status?
0 -> uninstantiated 1 -> instantiated <0 -> negatively instantiated/rejected
Also, can we make it a short int please?
Also, can setting this field be done with a release barrier rather than a write barrier?
David
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