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SubjectRe: [PATCH 06/12] genericirq: make irq_chip related function to take desc
On Sun, 21 Mar 2010, Eric W. Biederman wrote:

> Julia Lawall <julia@diku.dk> writes:
>
> > I also worked on this, but only sent it to Thomas and Yinghai. Onthe
> > other hand, I mostly like your solution better, because it has the
> > unintended side-effect of getting rid of some blank spaces after {s.
>
> Wow I hadn't noticed that {s removal. That is an old coding style
> violation on alpha. There was an intentional effect of not breaking
> up { }'s. But I hadn't realized I was also fixing whitespace.

I think it is because you added a local declaration of irq and then
removed it when it was not necessary. So then coccinelle was motivated to
remove the space after the {.

> > My rule was also more complicated in that it also searches for conditions
> > in which it is not sure to be doing the right thing. I will send those in
> > another message.
> >
> >> @ DECL @
> >> struct irq_chip CHIP;
> >> identifier METHOD;
> >> identifier METHOD_NAME;
> >> @@
> >> CHIP.METHOD_NAME = METHOD;
> >>
> >> @ @
> >> identifier DECL.METHOD;
> >> identifier IRQ;
> >> @@
> >> METHOD(
> >> - unsigned int IRQ
> >> + struct irq_desc *unused
> >> , ...) {
> >> }
> >
> > I didn't think of making a special rule for this. It could consider any
> > case where the body is ... when != IRQ
>
> Nice addition.
>
> >> @ @
> >> identifier DECL.METHOD;
> >> identifier IRQ;
> >> identifier DESC;
> >> @@
> >> METHOD(
> >> - unsigned int IRQ
> >> + struct irq_desc *DESC
> >> , ...) {
> >> + unsigned int IRQ = DESC->irq;
> >> ...
> >> - struct irq_desc *DESC = irq_to_desc(IRQ);
> >> ...
> >> }
> >>
> >> @ @
> >> identifier DECL.METHOD;
> >> identifier IRQ;
> >> identifier DESC;
> >> @@
> >> METHOD(
> >> - unsigned int IRQ
> >> + struct irq_desc *DESC
> >> , ...) {
> >> + unsigned int IRQ = DESC->irq;
> >> ...
> >> - struct irq_desc *DESC;
> >> ...
> >> - DESC = irq_to_desc(IRQ);
> >> ...
> >> }
> >>
> >> @ @
> >> identifier DECL.METHOD;
> >> identifier IRQ;
> >> @@
> >> METHOD(
> >> - unsigned int IRQ
> >> + struct irq_desc *desc
> >> , ...) {
> >> + unsigned int IRQ = desc->irq;
> >> ...
> >> }
> >>
> >> @ @
> >> identifier DECL.METHOD;
> >> identifier FUNC;
> >> identifier IRQ;
> >> @@
> >> FUNC(...) {
> >> <...
> >> METHOD(
> >> - IRQ
> >> + irq_to_desc(IRQ)
> >> , ... )
> >> ...>
> >> }
> >
> > I don't think FUNC(...) { <... and ...> } are needed here. The goal is to
> > make the change everywhere the call appears.
>
> That is a reasonable simplification.
>
> >> @ @
> >> identifier FUNC;
> >> identifier DESC;
> >> identifier IRQ;
> >> @@
> >> FUNC(..., struct irq_desc *DESC, ...) {
> >> ...
> >> unsigned int IRQ = DESC->irq;
> >> <...
> >> - irq_to_desc(IRQ)
> >> + DESC
> >> ...>
> >> }
> >
> > This rule can be extended as follows:
>
> Nice. I had not picked up on the or operator.
>
> > @ @
> > identifier FUNC;
> > identifier DESC;
> > identifier IRQ;
> > identifier FLD;
> > @@
> > FUNC(..., struct irq_desc *DESC, ...) {
> > ...
> > unsigned int IRQ = DESC->irq;
> > <...
> > (
> > - irq_to_desc(IRQ)
> > + DESC
> > |
> > - irq_desc[IRQ].FLD
> > + DESC->FLD
> > )
> > ...>
> > }
> >
> > Doing so gets rid of more references to IRQ.
>
> Very reasonable, especially on arches like alpha where none of the
> sparse irq work has hit.
>
>
> > Another case that can be treated is method calls via a pointer:
>
> I didn't actually find any cases where that rule hit on arch/x86
> so I did not include it, but it makes sense.
>
> > @@
> > expression arg;
> > struct irq_desc *desc;
> > struct irq_chip *ic;
> > identifier fun;
> > @@
> >
> > (
> > desc->chip->fun(
> > - arg
> > + desc
> > ,...)
> > |
> > ic->fun(
> > - arg
> > + irq_to_desc(arg)
> > ,...)
> > )
>
>
> My paranoid sense says this rule should be:
> @ @
> expresion IRQ_EXPR;
> struct irq_desc *DESC;
> struct irq_chip *CHIP;
> identifier METHOD;
> @@
> (
> DESC->chip->METHOD(
> - IRQ_EXPR
> + irq_to_desc(IRQ_EXPR)
> , ... )
> |
> CHIP->METHOD(
> - IRQ_EXPR
> + irq_to_desc(IRQ_EXPR)
> , ... )

Agreed. But then it would be nice to check whether DESC is already
computed as irq_to_desc(IRQ_EXPR).

julia

> If this is before my irq_to_desc removal rule. We should not
> see any new irq_to_desc calls popping up.
>
> > julia
> >
> >> @ @
> >> identifier FUNC;
> >> identifier DESC;
> >> identifier IRQ;
> >> @@
> >> FUNC(..., struct irq_desc *DESC, ...) {
> >> ...
> >> - unsigned int IRQ = DESC->irq;
> >> ... when != IRQ
> >> }
>


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