Re: [PATCH V14 01/10] acpi: apei: read ack upon ghes record consumption

[Baicar, Tyler]

On 4/11/2017 11:15 AM, Borislav Petkov wrote:
> On Tue, Mar 28, 2017 at 01:30:31PM -0600, Tyler Baicar wrote:
> > A RAS (Reliability, Availability, Serviceability) controller
> > may be a separate processor running in parallel with OS
> > execution, and may generate error records for consumption by
> > the OS. If the RAS controller produces multiple error records,
> > then they may be overwritten before the OS has consumed them.
> >
> > The Generic Hardware Error Source (GHES) v2 structure
> > introduces the capability for the OS to acknowledge the
> > consumption of the error record generated by the RAS
> > controller. A RAS controller supporting GHESv2 shall wait for
> > the acknowledgment before writing a new error record, thus
> > eliminating the race condition.
> >
> > Add support for parsing of GHESv2 sub-tables as well.
> >
> > Signed-off-by: Tyler Baicar <tbaicar@xxxxxxxxxxxxxx>
> > CC: Jonathan (Zhixiong) Zhang <zjzhang@xxxxxxxxxxxxxx>
> > Reviewed-by: James Morse <james.morse@xxxxxxx>
> > ---
> >   drivers/acpi/apei/ghes.c | 49 +++++++++++++++++++++++++++++++++++++++++++++---
> >   drivers/acpi/apei/hest.c |  7 +++++--
> >   include/acpi/ghes.h      |  5 ++++-
> >   3 files changed, 55 insertions(+), 6 deletions(-)
> ...
>
> > @@ -249,10 +254,18 @@ static struct ghes *ghes_new(struct acpi_hest_generic *generic)
> >   	ghes = kzalloc(sizeof(*ghes), GFP_KERNEL);
> >   	if (!ghes)
> >   		return ERR_PTR(-ENOMEM);
> > +
> >   	ghes->generic = generic;
> > +	if (IS_HEST_TYPE_GENERIC_V2(ghes)) {
> > +		rc = apei_map_generic_address(
> > +			&ghes->generic_v2->read_ack_register);
> Yeah, that linebreak just to keep the 80-cols rule makes the code ugly
> and hard to read.
>
> Please put that mapping and unmapping in wrappers called
> map_gen_v2(ghes) and unmap_gen_v2(ghes) or so, so that you can call them
> wherever needed. Thus should make the flow a bit more understandable
> what's going on and you won't have to repeat the unmapping lines in
> ghes_fini().
Hello Boris,

Thank you for the feedback. I will make this change in the next version.
> > @@ -649,6 +669,23 @@ static void ghes_estatus_cache_add(
> >   	rcu_read_unlock();
> >   }
> >   
> > +static int ghes_ack_error(struct acpi_hest_generic_v2 *generic_v2)
> > +{
> > +	int rc;
> > +	u64 val = 0;
> > +
> > +	rc = apei_read(&val, &generic_v2->read_ack_register);
> > +	if (rc)
> > +		return rc;
> > +	val &= generic_v2->read_ack_preserve <<
> > +		generic_v2->read_ack_register.bit_offset;
> > +	val |= generic_v2->read_ack_write <<
> > +		generic_v2->read_ack_register.bit_offset;
> Yeah, let them stick out, it more readable this way. Line spacing is
> helpful too:
>
> ...
>          rc = apei_read(&val, &generic_v2->read_ack_register);
>          if (rc)
>                  return rc;
>
>          val &= generic_v2->read_ack_preserve << generic_v2->read_ack_register.bit_offset;
>          val |= generic_v2->read_ack_write    << generic_v2->read_ack_register.bit_offset;
>
>          return apei_write(val, &generic_v2->read_ack_register);
> }
I will make this change in the next version.

Thanks,
Tyler
> > +	rc = apei_write(val, &generic_v2->read_ack_register);
> > +
> > +	return rc;
> > +}
> > +
> >   static int ghes_proc(struct ghes *ghes)
> >   {
> >   	int rc;

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