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    SubjectRe: [PATCH v22] edac, ras/hw_event.h: use events to handle hw issues
    It should be:

    Subject: RAS: Add a tracepoint for reporting memory controller errors

    and not

    Subject: edac, ras/hw_event.h: use events to handle hw issues

    because events don't handle hw issues.

    On Thu, May 10, 2012 at 04:56:28PM -0300, Mauro Carvalho Chehab wrote:
    > Add a new tracepoint-based hardware events report method for
    > outputing Memory Controller events.

    reporting

    >
    > Part of the description bellow is shamelessly copied from Tony
    > Luck's notes about the Hardware Error BoF during LPC 2010 [1].
    > Tony, thanks for your notes and discussions to generate the
    > h/w error reporting requirements.
    >
    > [1] http://lwn.net/Articles/416669/
    >
    > We have several subsystems & methods for reporting hardware errors:
    >
    > 1) EDAC ("Error Detection and Correction"). In its original form
    > this consisted of a platform specific driver that read topology
    > information and error counts from chipset registers and reported
    > the results via a sysfs interface.
    >
    > 2) mcelog - x86 specific decoding of machine check bank registers
    > reporting in binary form via /dev/mcelog. Recent additions make use
    > of the APEI extensions that were documented in version 4.0a of the
    > ACPI specification to acquire more information about errors without
    > having to rely reading chipset registers directly. A user level
    > programs decodes into somewhat human readable format.
    >
    > 3) drivers/edac/mce_amd.c - this driver hooks into the mcelog path and
    > decodes errors reported via machine check bank registers in AMD
    > processors to the console log using printk();
    >
    > Each of these mechanisms has a band of followers ... and none
    > of them appear to meet all the needs of all users.
    >
    > As part of a hardware event subsystem, let's encapsulate the memory
    > error hardware events into a trace facility.
    >
    > NOTE: The original patch was providing an additional mechanism for
    > MCA-based trace events that also contained MCA error register data.
    > Hoever, as no agreement was reached so far for the MCA-based trace
    > events, for now, let's add events only for memory errors.
    > A latter patch is planned to change the tracepoint, for those types
    > of event.
    >
    > Reviewed-by: Aristeu Rozanski <arozansk@redhat.com>
    > Cc: Doug Thompson <norsk5@yahoo.com>
    > Cc: Steven Rostedt <rostedt@goodmis.org>
    > Cc: Frederic Weisbecker <fweisbec@gmail.com>
    > Cc: Ingo Molnar <mingo@redhat.com>
    > Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
    > ---
    > drivers/edac/edac_core.h | 2 +-
    > drivers/edac/edac_mc.c | 25 +++++++++++----
    > include/ras/hw_event.h | 77 ++++++++++++++++++++++++++++++++++++++++++++++
    > 3 files changed, 96 insertions(+), 8 deletions(-)
    > create mode 100644 include/ras/hw_event.h
    >
    > diff --git a/drivers/edac/edac_core.h b/drivers/edac/edac_core.h
    > index f06ce9a..eee7360 100644
    > --- a/drivers/edac/edac_core.h
    > +++ b/drivers/edac/edac_core.h
    > @@ -468,7 +468,7 @@ void edac_mc_handle_error(const enum hw_event_mc_err_type type,
    > const int layer2,
    > const char *msg,
    > const char *other_detail,
    > - const void *mcelog);
    > + const void *arch_log);
    >
    > /*
    > * edac_device APIs
    > diff --git a/drivers/edac/edac_mc.c b/drivers/edac/edac_mc.c
    > index e5b5563..11f0178 100644
    > --- a/drivers/edac/edac_mc.c
    > +++ b/drivers/edac/edac_mc.c
    > @@ -33,6 +33,10 @@
    > #include "edac_core.h"
    > #include "edac_module.h"
    >
    > +#define CREATE_TRACE_POINTS
    > +#define TRACE_INCLUDE_PATH ../../include/ras
    > +#include <ras/hw_event.h>
    > +
    > /* lock to memory controller's control array */
    > static DEFINE_MUTEX(mem_ctls_mutex);
    > static LIST_HEAD(mc_devices);
    > @@ -381,6 +385,7 @@ struct mem_ctl_info *edac_mc_alloc(unsigned mc_num,
    > * which will perform kobj unregistration and the actual free
    > * will occur during the kobject callback operation
    > */
    > +
    > return mci;
    > }
    > EXPORT_SYMBOL_GPL(edac_mc_alloc);
    > @@ -982,7 +987,7 @@ void edac_mc_handle_error(const enum hw_event_mc_err_type type,
    > const int layer2,
    > const char *msg,
    > const char *other_detail,
    > - const void *mcelog)
    > + const void *arch_log)
    > {
    > /* FIXME: too much for stack: move it to some pre-alocated area */
    > char detail[80], location[80];
    > @@ -1119,21 +1124,27 @@ void edac_mc_handle_error(const enum hw_event_mc_err_type type,
    > }
    >
    > /* Memory type dependent details about the error */
    > - if (type == HW_EVENT_ERR_CORRECTED) {
    > + if (type == HW_EVENT_ERR_CORRECTED)
    > snprintf(detail, sizeof(detail),
    > "page:0x%lx offset:0x%lx grain:%d syndrome:0x%lx",
    > page_frame_number, offset_in_page,
    > grain, syndrome);
    > - edac_ce_error(mci, pos, msg, location, label, detail,
    > - other_detail, enable_per_layer_report,
    > - page_frame_number, offset_in_page, grain);
    > - } else {
    > + else
    > snprintf(detail, sizeof(detail),
    > "page:0x%lx offset:0x%lx grain:%d",
    > page_frame_number, offset_in_page, grain);
    >
    > + /* Report the error via the trace interface */
    > + trace_mc_error(type, mci->mc_idx, msg, label, location,
    > + detail, other_detail);
    > +
    > + /* Report the error via the edac_mc_printk() interface */
    > + if (type == HW_EVENT_ERR_CORRECTED)
    > + edac_ce_error(mci, pos, msg, location, label, detail,
    > + other_detail, enable_per_layer_report,
    > + page_frame_number, offset_in_page, grain);
    > + else
    > edac_ue_error(mci, pos, msg, location, label, detail,
    > other_detail, enable_per_layer_report);
    > - }
    > }
    > EXPORT_SYMBOL_GPL(edac_mc_handle_error);
    > diff --git a/include/ras/hw_event.h b/include/ras/hw_event.h
    > new file mode 100644
    > index 0000000..66981ef
    > --- /dev/null
    > +++ b/include/ras/hw_event.h
    > @@ -0,0 +1,77 @@
    > +#undef TRACE_SYSTEM
    > +#define TRACE_SYSTEM hw_event

    ras

    > +
    > +#if !defined(_TRACE_HW_EVENT_MC_H) || defined(TRACE_HEADER_MULTI_READ)
    > +#define _TRACE_HW_EVENT_MC_H
    > +
    > +#include <linux/tracepoint.h>
    > +#include <linux/edac.h>
    > +#include <linux/ktime.h>
    > +
    > +/*
    > + * Hardware Events Report
    > + *
    > + * Those events are generated when hardware detected a corrected or
    > + * uncorrected event, and are meant to replace the current API to report
    > + * errors defined on both EDAC and MCE subsystems.
    > + *
    > + * FIXME: Add events for handling memory errors originated from the
    > + * MCE subsystem.
    > + */
    > +
    > +/*
    > + * Hardware-independent Memory Controller specific events
    > + */
    > +
    > +/*
    > + * Default error mechanisms for Memory Controller errors (CE and UE)
    > + */
    > +TRACE_EVENT(mc_error,
    > +
    > + TP_PROTO(const unsigned int err_type,
    > + const unsigned int mc_index,
    > + const char *msg,
    > + const char *label,
    > + const char *location,
    > + const char *detail,
    > + const char *driver_detail),
    > +
    > + TP_ARGS(err_type, mc_index, msg, label, location,
    > + detail, driver_detail),
    > +
    > + TP_STRUCT__entry(
    > + __field( unsigned int, err_type )
    > + __field( unsigned int, mc_index )
    > + __string( msg, msg )
    > + __string( label, label )
    > + __string( detail, detail )
    > + __string( location, location )
    > + __string( driver_detail, driver_detail )
    > + ),
    > +
    > + TP_fast_assign(
    > + __entry->err_type = err_type;
    > + __entry->mc_index = mc_index;
    > + __assign_str(msg, msg);
    > + __assign_str(label, label);
    > + __assign_str(location, location);
    > + __assign_str(detail, detail);
    > + __assign_str(driver_detail, driver_detail);
    > + ),
    > +
    > + TP_printk(HW_ERR "mce#%d: %s error %s on memory stick \"%s\" (%s %s %s)",

    This still says "mce" and it should say "MC" or "mem_ctl" or similar.

    > + __entry->mc_index,
    > + (__entry->err_type == HW_EVENT_ERR_CORRECTED) ? "Corrected" :
    > + ((__entry->err_type == HW_EVENT_ERR_FATAL) ?
    > + "Fatal" : "Uncorrected"),
    > + __get_str(msg),
    > + __get_str(label),
    > + __get_str(location),
    > + __get_str(detail),
    > + __get_str(driver_detail))
    > +);
    > +
    > +#endif /* _TRACE_HW_EVENT_MC_H */
    > +
    > +/* This part must be outside protection */
    > +#include <trace/define_trace.h>

    I'm assuming you have all those changes on the experimental branch so
    that I can continue reviewing from there?

    @Tony: this is adding a RAS tracepoint for memory controller errors
    coming from EDAC (for now), any objections/issues?

    Thanks.

    --
    Regards/Gruss,
    Boris.

    Advanced Micro Devices GmbH
    Einsteinring 24, 85609 Dornach
    GM: Alberto Bozzo
    Reg: Dornach, Landkreis Muenchen
    HRB Nr. 43632 WEEE Registernr: 129 19551


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