Re: [PATCH] vfio_pci: set TRACE_INCLUDE_PATH to fix the build error

[Alex Williamson <alex.williamson@redhat.com>]

On Fri, 11 Jan 2019 12:13:35 +1100
Alexey Kardashevskiy <aik@ozlabs.ru> wrote:

> On 11/01/2019 01:47, Steven Rostedt wrote:
> > On Tue, Jan 08, 2019 at 12:08:03PM +0900, Masahiro Yamada wrote:  
> >> ---
> >>
> >>  drivers/vfio/pci/trace.h | 2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/vfio/pci/trace.h b/drivers/vfio/pci/trace.h
> >> index 228ccdb..4d13e51 100644
> >> --- a/drivers/vfio/pci/trace.h
> >> +++ b/drivers/vfio/pci/trace.h
> >> @@ -94,7 +94,7 @@ TRACE_EVENT(vfio_pci_npu2_mmap,
> >>  #endif /* _TRACE_VFIO_PCI_H */
> >>  
> >>  #undef TRACE_INCLUDE_PATH
> >> -#define TRACE_INCLUDE_PATH .
> >> +#define TRACE_INCLUDE_PATH ../../drivers/vfio/pci  
> > 
> > Note, the reason why I did not show this method in the samples/trace_events/
> > is that there's one "gotcha" that you need to be careful about. It may not be
> > an issue here, but please be aware of it.
> > 
> > The words in TRACE_INCLUDE_PATH can be updated by C preprocessor defines. For
> > example, if for some reason you had:
> > 
> > #define pci special_pci
> > 
> > The above would turn into:
> > 
> >  ../../drivers/vfio/special_pci
> > 
> > and it wont build, and you will be left scratching your head wondering why.  

Thanks for the info Steve, that'd definitely be a head scratcher, but
it also seems really unlikely for this path.

> Lovely :) imho it is +1 for
> CFLAGS_vfio_pci_nvlink2.o += -I$(src)
> and a comment.

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d1fc1176c055c9ec9c6ec4d113a284e0bad9d09a

Obviously we can still refine further, but I don't see this new piece
of information making a meaningful difference in the choice.  Thanks,

Alex