Re: [PATCHv12 7/9] asm-generic/io: Add logging support for MMIO accessors

[Sai Prakash Ranjan]

On 4/28/2022 5:32 PM, Greg KH wrote:
> On Thu, Apr 28, 2022 at 04:51:49PM +0530, Sai Prakash Ranjan wrote:
> > On 4/28/2022 4:21 PM, Greg KH wrote:
> > > On Thu, Apr 28, 2022 at 03:25:30PM +0530, Sai Prakash Ranjan wrote:
> > > > Add logging support for MMIO high level accessors such as read{b,w,l,q}
> > > > and their relaxed versions to aid in debugging unexpected crashes/hangs
> > > > caused by the corresponding MMIO operation.
> > > >
> > > > Signed-off-by: Sai Prakash Ranjan <quic_saipraka@xxxxxxxxxxx>
> > > > ---
> > > >    include/asm-generic/io.h | 82 ++++++++++++++++++++++++++++++++++++++--
> > > >    1 file changed, 78 insertions(+), 4 deletions(-)
> > > >
> > > > diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
> > > > index 7ce93aaf69f8..99090722cb4b 100644
> > > > --- a/include/asm-generic/io.h
> > > > +++ b/include/asm-generic/io.h
> > > > @@ -10,6 +10,7 @@
> > > >    #include <asm/page.h> /* I/O is all done through memory accesses */
> > > >    #include <linux/string.h> /* for memset() and memcpy() */
> > > >    #include <linux/types.h>
> > > > +#include <linux/instruction_pointer.h>
> > > >    #ifdef CONFIG_GENERIC_IOMAP
> > > >    #include <asm-generic/iomap.h>
> > > > @@ -61,6 +62,35 @@
> > > >    #define __io_par(v)     __io_ar(v)
> > > >    #endif
> > > > +#if IS_ENABLED(CONFIG_TRACE_MMIO_ACCESS) && !(defined(__DISABLE_TRACE_MMIO__))
> > > Shouldn't you document __DISABLE_TRACE_MMIO__ somewhere?  It's not even
> > > in the changelog.  Put a big comment above this for what is is for and
> > > how to use it.  Otherwise you will forget all about this in 6 months :)
> > >
> > > thanks,
> > >
> > > greg k-h
> > Didn't you ask me to split the patch to the one actually adding the flag and the one using it.
> Yes, and isn't this the commit that adds the flag?  Or was that on an
> earlier one that I missed?
>
> Ah, it's in patch 6/9
>
> But you should also document it here in the .h file, otherwise the only
> place it is described is in some random kvm Makefile that no one will
> ever notice :)

Sure it makes sense, will add it.

Thanks,
Sai