[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 2/2] x86: package up context switch hook pointers
On 15/02/17 08:42, Jan Beulich wrote: >>>> On 14.02.17 at 16:26, <andrew.cooper3@xxxxxxxxxx> wrote: >> On 14/02/17 10:29, Jan Beulich wrote: >>> @@ -2066,6 +2073,15 @@ static void __context_switch(void) >>> per_cpu(curr_vcpu, cpu) = n; >>> } >>> >>> +/* >>> + * Schedule tail *should* be a terminal function pointer, but leave a >>> bugframe >>> + * around just incase it returns, to save going back into the context >>> + * switching code and leaving a far more subtle crash to diagnose. >>> + */ >>> +#define schedule_tail(vcpu) do { \ >>> + (((vcpu)->domain->arch.ctxt_switch->tail)(vcpu)); \ >>> + BUG(); \ >>> + } while (0) >> schedule_tail() is used only twice. I'd suggest dropping it entirely >> and calling the ->tail() function pointer normally, rather than hiding >> it this. > I had considered this too, and now that you ask for it I'll happily > do so. Thinking more, it would be a good idea to annotate the respective functions noreturn, so the compiler will catch anyone who accidently puts a return statement in. > >> Upon reviewing, this patch, don't we also need a ->same() call in the >> continue_same() path in the previous patch? > No, I did specifically check this already: The call to continue_same() > sits (far) ahead of the clearing of ->is_running, and as long as that > flag is set, vcpu_pause() (or vcpu_sleep_sync(), to be precise) will > spin as necessary. Ok. ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
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