[RFC patch 3/9] selftests/resctrl: Use dynamic linked list for iMC counters config
Yifan Wu
wuyifan50 at huawei.com
Tue Mar 3 20:03:28 PST 2026
Currently, a fixed-size array is used to store the configurations for
all discovered iMC counters, which has several issues:
1. Fixed Overhead: The array is allocated a fixed size, even if the
platform has fewer iMCs.
2. Out-of-Bounds Access: On platforms with more iMC counters than
MAX_IMCS, the num_of_imcs() function can return a larger number, leading
to an array index out-of-bounds access.
3. Reduced Maintainability: The need to statically define MAX_IMCS for
different architectures and vendors makes the code harder to maintain.
4. Redundancy: The num_of_imcs() function dynamically discovers the
actual number of counters, making the static size declaration unnecessary
and redundant.
To address these issues, this commit refactors resctrl_val.c to use
a dynamic linked list. The num_of_imcs() function now allocates and
configures an imc_counter_config structure for each discovered iMC and
adds it to a global list (imc_counters_configs). This change ensures that
only the required memory is used and prevents the out-of-bounds issue.
Additionally, a corresponding cleanup_read_mem_bw_imc() function
is added to iterate through the list and free all allocated memory,
preventing leaks.
All function signatures that previously accepted an integer index have
been updated to accept a pointer to the imc_counter_config struct,
and the calling code has been updated to traverse the new list.
Signed-off-by: Yifan Wu <wuyifan50 at huawei.com>
---
tools/testing/selftests/resctrl/resctrl.h | 1 +
tools/testing/selftests/resctrl/resctrl_val.c | 132 ++++++++++--------
2 files changed, 78 insertions(+), 55 deletions(-)
diff --git a/tools/testing/selftests/resctrl/resctrl.h b/tools/testing/selftests/resctrl/resctrl.h
index afe635b6e48d..75c595812e7d 100644
--- a/tools/testing/selftests/resctrl/resctrl.h
+++ b/tools/testing/selftests/resctrl/resctrl.h
@@ -24,6 +24,7 @@
#include <linux/perf_event.h>
#include <linux/compiler.h>
#include <linux/bits.h>
+#include <linux/list.h>
#include "kselftest.h"
#define MB (1024 * 1024)
diff --git a/tools/testing/selftests/resctrl/resctrl_val.c b/tools/testing/selftests/resctrl/resctrl_val.c
index b0570c615aac..68e46c863474 100644
--- a/tools/testing/selftests/resctrl/resctrl_val.c
+++ b/tools/testing/selftests/resctrl/resctrl_val.c
@@ -11,7 +11,6 @@
#include "resctrl.h"
#define DYN_PMU_PATH "/sys/bus/event_source/devices"
-#define MAX_IMCS 20
#define MAX_TOKENS 5
#define CON_MBM_LOCAL_BYTES_PATH \
@@ -31,6 +30,7 @@ struct imc_counter_config {
struct perf_event_attr pe;
struct membw_read_format return_value;
int fd;
+ struct list_head imc_list;
};
struct membw_read_config {
@@ -38,14 +38,18 @@ struct membw_read_config {
const char *name;
const char *event;
double scale;
+ int (*num_of)(void);
};
+static int num_of_imcs(void);
+
static struct membw_read_config membw_read_configs[] = {
{
.vendor_id = ARCH_INTEL | ARCH_AMD | ARCH_HYGON,
.name = "uncore_imc",
.event = "events/cas_count_read",
.scale = 64.0 / MB,
+ .num_of = num_of_imcs,
},
{
.vendor_id = NULL
@@ -53,37 +57,38 @@ static struct membw_read_config membw_read_configs[] = {
};
static char mbm_total_path[1024];
-static int imcs;
-static struct imc_counter_config imc_counters_config[MAX_IMCS];
+LIST_HEAD(imc_counters_configs);
static const struct resctrl_test *current_test;
static struct membw_read_config *current_config;
-static void read_mem_bw_initialize_perf_event_attr(int i)
+static void read_mem_bw_initialize_perf_event_attr(struct imc_counter_config *imc_counters_config)
{
- memset(&imc_counters_config[i].pe, 0,
+ memset(&imc_counters_config->pe, 0,
sizeof(struct perf_event_attr));
- imc_counters_config[i].pe.type = imc_counters_config[i].type;
- imc_counters_config[i].pe.size = sizeof(struct perf_event_attr);
- imc_counters_config[i].pe.disabled = 1;
- imc_counters_config[i].pe.inherit = 1;
- imc_counters_config[i].pe.exclude_guest = 0;
- imc_counters_config[i].pe.config =
- imc_counters_config[i].umask << 8 |
- imc_counters_config[i].event;
- imc_counters_config[i].pe.sample_type = PERF_SAMPLE_IDENTIFIER;
- imc_counters_config[i].pe.read_format =
+ imc_counters_config->pe.type = imc_counters_config->type;
+ imc_counters_config->pe.size = sizeof(struct perf_event_attr);
+ imc_counters_config->pe.disabled = 1;
+ imc_counters_config->pe.inherit = 1;
+ imc_counters_config->pe.exclude_guest = 0;
+ imc_counters_config->pe.config =
+ imc_counters_config->umask << 8 |
+ imc_counters_config->event;
+ imc_counters_config->pe.sample_type = PERF_SAMPLE_IDENTIFIER;
+ imc_counters_config->pe.read_format =
PERF_FORMAT_TOTAL_TIME_ENABLED | PERF_FORMAT_TOTAL_TIME_RUNNING;
}
-static void read_mem_bw_ioctl_perf_event_ioc_reset_enable(int i)
+static void read_mem_bw_ioctl_perf_event_ioc_reset_enable(struct imc_counter_config
+ *imc_counters_config)
{
- ioctl(imc_counters_config[i].fd, PERF_EVENT_IOC_RESET, 0);
- ioctl(imc_counters_config[i].fd, PERF_EVENT_IOC_ENABLE, 0);
+ ioctl(imc_counters_config->fd, PERF_EVENT_IOC_RESET, 0);
+ ioctl(imc_counters_config->fd, PERF_EVENT_IOC_ENABLE, 0);
}
-static void read_mem_bw_ioctl_perf_event_ioc_disable(int i)
+static void read_mem_bw_ioctl_perf_event_ioc_disable(struct imc_counter_config
+ *imc_counters_config)
{
- ioctl(imc_counters_config[i].fd, PERF_EVENT_IOC_DISABLE, 0);
+ ioctl(imc_counters_config->fd, PERF_EVENT_IOC_DISABLE, 0);
}
/*
@@ -91,7 +96,8 @@ static void read_mem_bw_ioctl_perf_event_ioc_disable(int i)
* @cas_count_cfg: Config
* @count: iMC number
*/
-static void get_read_event_and_umask(char *cas_count_cfg, int count)
+static void get_read_event_and_umask(char *cas_count_cfg, struct imc_counter_config
+ *imc_counters_config)
{
char *token[MAX_TOKENS];
int i = 0;
@@ -105,21 +111,21 @@ static void get_read_event_and_umask(char *cas_count_cfg, int count)
if (!token[i])
break;
if (strcmp(token[i], "event") == 0)
- imc_counters_config[count].event = strtol(token[i + 1], NULL, 16);
+ imc_counters_config->event = strtol(token[i + 1], NULL, 16);
if (strcmp(token[i], "umask") == 0)
- imc_counters_config[count].umask = strtol(token[i + 1], NULL, 16);
+ imc_counters_config->umask = strtol(token[i + 1], NULL, 16);
}
}
-static int open_perf_read_event(int i, int cpu_no)
+static int open_perf_read_event(struct imc_counter_config *imc_counters_config, int cpu_no)
{
- imc_counters_config[i].fd =
- perf_event_open(&imc_counters_config[i].pe, -1, cpu_no, -1,
+ imc_counters_config->fd =
+ perf_event_open(&imc_counters_config->pe, -1, cpu_no, -1,
PERF_FLAG_FD_CLOEXEC);
- if (imc_counters_config[i].fd == -1) {
+ if (imc_counters_config->fd == -1) {
fprintf(stderr, "Error opening leader %llx\n",
- imc_counters_config[i].pe.config);
+ imc_counters_config->pe.config);
return -1;
}
@@ -128,7 +134,7 @@ static int open_perf_read_event(int i, int cpu_no)
}
/* Get type and config of an iMC counter's read event. */
-static int read_from_imc_dir(char *imc_dir, int count)
+static int read_from_imc_dir(char *imc_dir, struct imc_counter_config *imc_counters_config)
{
char cas_count_cfg[1024], imc_counter_cfg[1024], imc_counter_type[1024];
FILE *fp;
@@ -141,7 +147,7 @@ static int read_from_imc_dir(char *imc_dir, int count)
return -1;
}
- if (fscanf(fp, "%u", &imc_counters_config[count].type) <= 0) {
+ if (fscanf(fp, "%u", &imc_counters_config->type) <= 0) {
ksft_perror("Could not get iMC type");
fclose(fp);
@@ -165,7 +171,7 @@ static int read_from_imc_dir(char *imc_dir, int count)
}
fclose(fp);
- get_read_event_and_umask(cas_count_cfg, count);
+ get_read_event_and_umask(cas_count_cfg, imc_counters_config);
return 0;
}
@@ -189,6 +195,7 @@ static int num_of_imcs(void)
struct dirent *ep;
int ret;
DIR *dp;
+ struct imc_counter_config *imc_counters_config;
dp = opendir(DYN_PMU_PATH);
if (dp) {
@@ -212,14 +219,17 @@ static int num_of_imcs(void)
* first character is a numerical digit or not.
*/
if (temp[0] >= '0' && temp[0] <= '9') {
+ imc_counters_config = malloc(sizeof(struct imc_counter_config));
sprintf(imc_dir, "%s/%s/", DYN_PMU_PATH,
ep->d_name);
- ret = read_from_imc_dir(imc_dir, count);
+ ret = read_from_imc_dir(imc_dir, imc_counters_config);
if (ret) {
+ free(imc_counters_config);
closedir(dp);
return ret;
}
+ list_add(&imc_counters_config->imc_list, &imc_counters_configs);
count++;
}
}
@@ -240,26 +250,40 @@ static int num_of_imcs(void)
int initialize_read_mem_bw_imc(void)
{
- int imc;
+ struct imc_counter_config *imc_counters_config;
- imcs = num_of_imcs();
+ int imcs = current_config->num_of();
if (imcs <= 0)
return imcs;
/* Initialize perf_event_attr structures for all iMC's */
- for (imc = 0; imc < imcs; imc++)
- read_mem_bw_initialize_perf_event_attr(imc);
+ list_for_each_entry(imc_counters_config, &imc_counters_configs, imc_list) {
+ read_mem_bw_initialize_perf_event_attr(imc_counters_config);
+ }
return 0;
}
+void cleanup_read_mem_bw_imc(void)
+{
+ struct imc_counter_config *imc_counters_config;
+ struct imc_counter_config *next_imc_counters_config;
+
+ list_for_each_entry_safe(imc_counters_config, next_imc_counters_config,
+ &imc_counters_configs, imc_list) {
+ list_del(&imc_counters_config->imc_list);
+ free(imc_counters_config);
+ }
+ list_del_init(&imc_counters_configs);
+}
+
static void perf_close_imc_read_mem_bw(void)
{
- int mc;
+ struct imc_counter_config *imc_counters_config;
- for (mc = 0; mc < imcs; mc++) {
- if (imc_counters_config[mc].fd != -1)
- close(imc_counters_config[mc].fd);
+ list_for_each_entry(imc_counters_config, &imc_counters_configs, imc_list) {
+ if (imc_counters_config->fd != -1)
+ close(imc_counters_config->fd);
}
}
@@ -271,13 +295,14 @@ static void perf_close_imc_read_mem_bw(void)
*/
static int perf_open_imc_read_mem_bw(int cpu_no)
{
- int imc, ret;
+ int ret;
+ struct imc_counter_config *imc_counters_config;
- for (imc = 0; imc < imcs; imc++)
- imc_counters_config[imc].fd = -1;
+ list_for_each_entry(imc_counters_config, &imc_counters_configs, imc_list)
+ imc_counters_config->fd = -1;
- for (imc = 0; imc < imcs; imc++) {
- ret = open_perf_read_event(imc, cpu_no);
+ list_for_each_entry(imc_counters_config, &imc_counters_configs, imc_list) {
+ ret = open_perf_read_event(imc_counters_config, cpu_no);
if (ret)
goto close_fds;
}
@@ -297,16 +322,16 @@ static int perf_open_imc_read_mem_bw(int cpu_no)
*/
static void do_imc_read_mem_bw_test(void)
{
- int imc;
+ struct imc_counter_config *imc_counters_config;
- for (imc = 0; imc < imcs; imc++)
- read_mem_bw_ioctl_perf_event_ioc_reset_enable(imc);
+ list_for_each_entry(imc_counters_config, &imc_counters_configs, imc_list)
+ read_mem_bw_ioctl_perf_event_ioc_reset_enable(imc_counters_config);
sleep(1);
/* Stop counters after a second to get results. */
- for (imc = 0; imc < imcs; imc++)
- read_mem_bw_ioctl_perf_event_ioc_disable(imc);
+ list_for_each_entry(imc_counters_config, &imc_counters_configs, imc_list)
+ read_mem_bw_ioctl_perf_event_ioc_disable(imc_counters_config);
}
/*
@@ -321,17 +346,14 @@ static void do_imc_read_mem_bw_test(void)
static int get_read_mem_bw_imc(float *bw_imc)
{
float reads = 0, of_mul_read = 1;
- int imc;
+ struct imc_counter_config *r;
/*
* Log read event values from all iMC counters into
* struct imc_counter_config.
* Take overflow into consideration before calculating total bandwidth.
*/
- for (imc = 0; imc < imcs; imc++) {
- struct imc_counter_config *r =
- &imc_counters_config[imc];
-
+ list_for_each_entry(r, &imc_counters_configs, imc_list) {
if (read(r->fd, &r->return_value,
sizeof(struct membw_read_format)) == -1) {
ksft_perror("Couldn't get read bandwidth through iMC");
--
2.33.0
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