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SubjectRe: [PATCH V14 01/10] acpi: apei: read ack upon ghes record consumption
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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@codeaurora.org>
>> CC: Jonathan (Zhixiong) Zhang <zjzhang@codeaurora.org>
>> Reviewed-by: James Morse <james.morse@arm.com>
>> ---
>> 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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Qualcomm Technologies, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project.

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