Re: [PATCH v2] buffer: Fix I/O error due to ARM read-after-read hazard

[Herbert Xu]

Will Deacon <will@xxxxxxxxxx> wrote:
>
> which is what can happen due to this erratum. It's generally good practice
> to use READ_ONCE() when reading something which can be updated concurrently
> because:
> 
>        * It ensures that the value is (re-)loaded from memory
> 
>        * It prevents the compiler from performing harmful optimisations,
>          such as merging or tearing (although in this case I suspect
>          these are ok because we're dealing with a single bit)
> 
>        * On Alpha, it gives you a barrier so that dependency ordering
>          can be relied upon from the load

The Alpha barrier matters for pointers, how could it make a
difference for individual bits?

Cheers,
-- 
Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
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