Re: [Xen-devel] [PATCH v6 06/18] vmx: Add some helper functions for Posted-Interrupts

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 06.09.15 at 04:05, <feng.wu@xxxxxxxxx> wrote:

> 
>> -----Original Message-----
>> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
>> Sent: Friday, September 04, 2015 10:40 PM
>> To: Wu, Feng
>> Cc: Andrew Cooper; Tian, Kevin; xen-devel@xxxxxxxxxxxxx; Keir Fraser
>> Subject: Re: [PATCH v6 06/18] vmx: Add some helper functions for
>> Posted-Interrupts
>> 
>> >>> On 25.08.15 at 03:57, <feng.wu@xxxxxxxxx> wrote:
>> > @@ -121,11 +122,31 @@ static inline int pi_test_and_clear_on(struct
>> pi_desc *pi_desc)
>> >      return test_and_clear_bit(POSTED_INTR_ON, &pi_desc->control);
>> >  }
>> >
>> > +static inline int pi_test_on(struct pi_desc *pi_desc)
>> > +{
>> > +    return test_bit(POSTED_INTR_ON, &pi_desc->control);
>> > +}
>> 
>> For this and ...
>> 
>> > +static inline int pi_test_sn(struct pi_desc *pi_desc)
>> > +{
>> > +    return test_bit(POSTED_INTR_SN, &pi_desc->control);
>> > +}
>> 
>> ... this I wonder whether using the bitfield you defined in the
>> previous patch wouldn't allow the compiler more freedom in
>> how to carry this out.
> 
> I am sorry, I don't quite understand it. Do you mean: the bitfield
> defined in previous patch is pointless, or using the bitfield here?

Use it here would seem preferable. (But please recall that I
questioned this two fold access model - partly using bitfields,
partly using bitops - earlier on, and ideally _all_ accesses to
a certain kind of data structure would follow a single, uniform
model.)

Jan


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