[PATCH 2/2] powerpc/powernv/opal-dump : Use IRQ_HANDLED instead of numbers in interrupt handler

[Jeremy Kerr]

Hi Mukesh,

>> Unless I'm mistaken, there are two things I can see happening with the
>> old code: if we hit the IRQ_NONE path enough, we'll report a "nobody
>> cared" error (see __report_bad_irq) and disable the interrupt, or for
>> the -1 case, we'll immediately log a "bogus return value" error (and, it
>> looks like a "no thread function available" error too, from
>> warn_no_thread).
> 
> bogus return value" error will not come as
> 
> action_ret <= (IRQ_HANDLED | IRQ_WAKE_THREAD)
> i.e
>         0/-1 <= 3 (true)

Well, no. irqreturn_t is an enum, and is being treated as an unsigned
value (the signed/unsigned behaviour of an enum is
implementation-defined), and:

          0xffffffff > 3

so we will *probably* see the bogus return value warning here (based on
some brief experimentation with gcc), but that does depend on the
compiler.

I've submitted a patch to make that comparison more obvious and
explicit:

  https://marc.info/?l=linux-kernel&m=148721917302673

Cheers,


Jeremy