Re: [Xen-devel] [PATCH 2/2] x86: package up context switch hook pointers

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 15.02.17 at 12:34, <andrew.cooper3@xxxxxxxxxx> wrote:
> 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.

Right, but in another patch I would say.

Jan


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