On 06/04/2017 23:08, Andrew Jones wrote:
> My own made-up lingo to state that each time the variable is accessed it
> must be loaded anew, taken care of by the volatile use in READ_ONCE. As
> vcpu->requests can be written by other threads, then I prefer READ_ONCE
> being used to read it, as it allows me to avoid spending energy convincing
> myself that the compiler would have emitted a load at that point anyway.
Also, READ_ONCE without a barrier is really fishy unless it's
while (READ_ONCE(x) != 2) {
...
}
or similar, and WRITE_ONCE doesn't even have this exception. So
annotating variables accessed by multiple threads with
READ_ONCE/WRITE_ONCE is generally a good idea.
Paolo
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