| Subject | Re: [RESEND][PATCH v3 14/17] static_call: Add static_cond_call() | From | Rasmus Villemoes <> | Date | Fri, 27 Mar 2020 00:37:35 +0100 |
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On 24/03/2020 14.56, Peter Zijlstra wrote: > Extend the static_call infrastructure to optimize the following common > pattern: > > if (func_ptr) > func_ptr(args...) >
> +#define DEFINE_STATIC_COND_CALL(name, _func) \ > + DECLARE_STATIC_CALL(name, _func); \ > + struct static_call_key STATIC_CALL_NAME(name) = { \ > + .func = NULL, \ > + } > + > #define static_call(name) \ > ((typeof(STATIC_CALL_TRAMP(name))*)(STATIC_CALL_NAME(name).func)) > > +#define static_cond_call(name) \ > + if (STATIC_CALL_NAME(name).func) \ > + ((typeof(STATIC_CALL_TRAMP(name))*)(STATIC_CALL_NAME(name).func)) > +
What, apart from fear of being ridiculed by kernel folks, prevents the compiler from reloading STATIC_CALL_NAME(name).func ? IOW, doesn't this want a READ_ONCE somewhere?
And please remind me, what is the consensus for sizeof(long) loads: does static_call() need load-tearing protection or not?
Rasmus
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