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edac: reduce stack pressure by using a pre-allocated buffer
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The number of variables at the stack is too big.
Reduces the stack usage by using a pre-allocated error
buffer.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
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Mauro Carvalho Chehab committed Feb 21, 2013
1 parent 80cc7d8 commit c7ef764
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Showing 2 changed files with 104 additions and 33 deletions.
81 changes: 48 additions & 33 deletions drivers/edac/edac_mc.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1065,7 +1065,6 @@ static void edac_ue_error(struct mem_ctl_info *mci,
edac_inc_ue_error(mci, enable_per_layer_report, pos, error_count);
}

#define OTHER_LABEL " or "

/**
* edac_mc_handle_error - reports a memory event to userspace
Expand Down Expand Up @@ -1097,19 +1096,28 @@ void edac_mc_handle_error(const enum hw_event_mc_err_type type,
const char *msg,
const char *other_detail)
{
/* FIXME: too much for stack: move it to some pre-alocated area */
char detail[80], location[80];
char label[(EDAC_MC_LABEL_LEN + 1 + sizeof(OTHER_LABEL)) * mci->tot_dimms];
char detail[80];
char *p;
int row = -1, chan = -1;
int pos[EDAC_MAX_LAYERS] = { top_layer, mid_layer, low_layer };
int i;
long grain;
bool enable_per_layer_report = false;
int i, n_labels = 0;
u8 grain_bits;
struct edac_raw_error_desc *e = &mci->error_desc;

edac_dbg(3, "MC%d\n", mci->mc_idx);

/* Fills the error report buffer */
memset(e, 0, sizeof (*e));
e->error_count = error_count;
e->top_layer = top_layer;
e->mid_layer = mid_layer;
e->low_layer = low_layer;
e->page_frame_number = page_frame_number;
e->offset_in_page = offset_in_page;
e->syndrome = syndrome;
e->msg = msg;
e->other_detail = other_detail;

/*
* Check if the event report is consistent and if the memory
* location is known. If it is known, enable_per_layer_report will be
Expand All @@ -1132,7 +1140,7 @@ void edac_mc_handle_error(const enum hw_event_mc_err_type type,
pos[i] = -1;
}
if (pos[i] >= 0)
enable_per_layer_report = true;
e->enable_per_layer_report = true;
}

/*
Expand All @@ -1146,8 +1154,7 @@ void edac_mc_handle_error(const enum hw_event_mc_err_type type,
* where each memory belongs to a separate channel within the same
* branch.
*/
grain = 0;
p = label;
p = e->label;
*p = '\0';

for (i = 0; i < mci->tot_dimms; i++) {
Expand All @@ -1161,17 +1168,22 @@ void edac_mc_handle_error(const enum hw_event_mc_err_type type,
continue;

/* get the max grain, over the error match range */
if (dimm->grain > grain)
grain = dimm->grain;
if (dimm->grain > e->grain)
e->grain = dimm->grain;

/*
* If the error is memory-controller wide, there's no need to
* seek for the affected DIMMs because the whole
* channel/memory controller/... may be affected.
* Also, don't show errors for empty DIMM slots.
*/
if (enable_per_layer_report && dimm->nr_pages) {
if (p != label) {
if (e->enable_per_layer_report && dimm->nr_pages) {
if (n_labels >= EDAC_MAX_LABELS) {
e->enable_per_layer_report = false;
break;
}
n_labels++;
if (p != e->label) {
strcpy(p, OTHER_LABEL);
p += strlen(OTHER_LABEL);
}
Expand All @@ -1198,12 +1210,12 @@ void edac_mc_handle_error(const enum hw_event_mc_err_type type,
}
}

if (!enable_per_layer_report) {
strcpy(label, "any memory");
if (!e->enable_per_layer_report) {
strcpy(e->label, "any memory");
} else {
edac_dbg(4, "csrow/channel to increment: (%d,%d)\n", row, chan);
if (p == label)
strcpy(label, "unknown memory");
if (p == e->label)
strcpy(e->label, "unknown memory");
if (type == HW_EVENT_ERR_CORRECTED) {
if (row >= 0) {
mci->csrows[row]->ce_count += error_count;
Expand All @@ -1216,7 +1228,7 @@ void edac_mc_handle_error(const enum hw_event_mc_err_type type,
}

/* Fill the RAM location data */
p = location;
p = e->location;

for (i = 0; i < mci->n_layers; i++) {
if (pos[i] < 0)
Expand All @@ -1226,32 +1238,35 @@ void edac_mc_handle_error(const enum hw_event_mc_err_type type,
edac_layer_name[mci->layers[i].type],
pos[i]);
}
if (p > location)
if (p > e->location)
*(p - 1) = '\0';

/* Report the error via the trace interface */
grain_bits = fls_long(grain) + 1;
trace_mc_event(type, msg, label, error_count,
mci->mc_idx, top_layer, mid_layer, low_layer,
PAGES_TO_MiB(page_frame_number) | offset_in_page,
grain_bits, syndrome, other_detail);
grain_bits = fls_long(e->grain) + 1;
trace_mc_event(type, e->msg, e->label, e->error_count,
mci->mc_idx, e->top_layer, e->mid_layer, e->low_layer,
PAGES_TO_MiB(e->page_frame_number) | e->offset_in_page,
grain_bits, e->syndrome, other_detail);

/* Memory type dependent details about the error */
if (type == HW_EVENT_ERR_CORRECTED) {
snprintf(detail, sizeof(detail),
"page:0x%lx offset:0x%lx grain:%ld syndrome:0x%lx",
page_frame_number, offset_in_page,
grain, syndrome);
edac_ce_error(mci, error_count, pos, msg, location, label,
detail, other_detail, enable_per_layer_report,
page_frame_number, offset_in_page, grain);
e->page_frame_number, e->offset_in_page,
e->grain, e->syndrome);
edac_ce_error(mci, e->error_count, pos, e->msg, e->location,
e->label, detail, other_detail,
e->enable_per_layer_report,
e->page_frame_number, e->offset_in_page,
e->grain);
} else {
snprintf(detail, sizeof(detail),
"page:0x%lx offset:0x%lx grain:%ld",
page_frame_number, offset_in_page, grain);
page_frame_number, offset_in_page, e->grain);

edac_ue_error(mci, error_count, pos, msg, location, label,
detail, other_detail, enable_per_layer_report);
edac_ue_error(mci, e->error_count, pos, e->msg, e->location,
e->label, detail, other_detail,
e->enable_per_layer_report);
}
}
EXPORT_SYMBOL_GPL(edac_mc_handle_error);
56 changes: 56 additions & 0 deletions include/linux/edac.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -47,8 +47,18 @@ static inline void opstate_init(void)
return;
}

/* Max length of a DIMM label*/
#define EDAC_MC_LABEL_LEN 31

/* Maximum size of the location string */
#define LOCATION_SIZE 80

/* Defines the maximum number of labels that can be reported */
#define EDAC_MAX_LABELS 8

/* String used to join two or more labels */
#define OTHER_LABEL " or "

/**
* enum dev_type - describe the type of memory DRAM chips used at the stick
* @DEV_UNKNOWN: Can't be determined, or MC doesn't support detect it
Expand Down Expand Up @@ -553,6 +563,46 @@ struct errcount_attribute_data {
int layer0, layer1, layer2;
};

/**
* edac_raw_error_desc - Raw error report structure
* @grain: minimum granularity for an error report, in bytes
* @error_count: number of errors of the same type
* @top_layer: top layer of the error (layer[0])
* @mid_layer: middle layer of the error (layer[1])
* @low_layer: low layer of the error (layer[2])
* @page_frame_number: page where the error happened
* @offset_in_page: page offset
* @syndrome: syndrome of the error (or 0 if unknown or if
* the syndrome is not applicable)
* @msg: error message
* @location: location of the error
* @label: label of the affected DIMM(s)
* @other_detail: other driver-specific detail about the error
* @enable_per_layer_report: if false, the error affects all layers
* (typically, a memory controller error)
*/
struct edac_raw_error_desc {
/*
* NOTE: everything before grain won't be cleaned by
* edac_raw_error_desc_clean()
*/
char location[LOCATION_SIZE];
char label[(EDAC_MC_LABEL_LEN + 1 + sizeof(OTHER_LABEL)) * EDAC_MAX_LABELS];
long grain;

/* the vars below and grain will be cleaned on every new error report */
u16 error_count;
int top_layer;
int mid_layer;
int low_layer;
unsigned long page_frame_number;
unsigned long offset_in_page;
unsigned long syndrome;
const char *msg;
const char *other_detail;
bool enable_per_layer_report;
};

/* MEMORY controller information structure
*/
struct mem_ctl_info {
Expand Down Expand Up @@ -660,6 +710,12 @@ struct mem_ctl_info {
/* work struct for this MC */
struct delayed_work work;

/*
* Used to report an error - by being at the global struct
* makes the memory allocated by the EDAC core
*/
struct edac_raw_error_desc error_desc;

/* the internal state of this controller instance */
int op_state;

Expand Down

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