Messages in this thread | | | Subject | Re: [PATCH net-next 05/12] ptr_ring: disallow lockless __ptr_ring_full | From | Jason Wang <> | Date | Mon, 29 Jan 2018 15:09:49 +0800 |
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On 2018年01月29日 12:41, Michael S. Tsirkin wrote: > On Mon, Jan 29, 2018 at 11:36:09AM +0800, Jason Wang wrote: >> >> On 2018年01月26日 10:46, Michael S. Tsirkin wrote: >>>> On 2018年01月26日 07:36, Michael S. Tsirkin wrote: >>>>> Similar to bcecb4bbf88a ("net: ptr_ring: otherwise safe empty checks can >>>>> overrun array bounds") a lockless use of __ptr_ring_full might >>>>> cause an out of bounds access. >>>>> >>>>> We can fix this, but it's easier to just disallow lockless >>>>> __ptr_ring_full for now. >>>> It looks to me that just fix this is better than disallow through doc (which >>>> is easily to be ignored ...). >>>> >>>> Thanks >>> lockless is tricky, and I'd rather not sprinkle READ/WRITE_ONCE where >>> they aren't necessary. >>> >> The problem is then API looks a little bit strange. Lockless were only >> allowed to be done at __ptr_ring_empty() but not __ptr_ring_full(). >> >> Thanks > So __ptr_ring_empty doesn't really work lockless. It merely does not crash. > I don't believe we can do anything to remove the need to read the > docs unless people use the safe non __ variants. >
Ok, then I will ack the series.
Thanks
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