[PATCH v4 01/16] selftests/resctrl: Fix closing IMC fds on error and open-code R+W instead of loops

[Ilpo Järvinen]

The imc perf fd close() calls are missing from all error paths. In
addition, get_mem_bw_imc() handles fds in a for loop but close() is
based on two fixed indexes READ and WRITE.

Open code inner for loops to READ+WRITE entries for clarity and add a
function to close() IMC fds properly in all cases.

Fixes: 7f4d257e3a2a ("selftests/resctrl: Add callback to start a benchmark")
Suggested-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
---

v4:
- Merge with the fix close patch
- Add loop to reset imc_counters_config fds to -1 to be able know which
  need closing
- Introduce perf_close_imc_mem_bw() to close fds
v3:
- Rework entirely, use open coding instead of for loops for clarity
---
 tools/testing/selftests/resctrl/resctrl_val.c | 54 ++++++++++++-------
 1 file changed, 36 insertions(+), 18 deletions(-)

diff --git a/tools/testing/selftests/resctrl/resctrl_val.c b/tools/testing/selftests/resctrl/resctrl_val.c
index 445f306d4c2f..f55f5989de72 100644
--- a/tools/testing/selftests/resctrl/resctrl_val.c
+++ b/tools/testing/selftests/resctrl/resctrl_val.c
@@ -293,6 +293,18 @@ static int initialize_mem_bw_imc(void)
 	return 0;
 }
 
+static void perf_close_imc_mem_bw(void)
+{
+	int mc;
+
+	for (mc = 0; mc < imcs; mc++) {
+		if (imc_counters_config[mc][READ].fd != -1)
+			close(imc_counters_config[mc][READ].fd);
+		if (imc_counters_config[mc][WRITE].fd != -1)
+			close(imc_counters_config[mc][WRITE].fd);
+	}
+}
+
 /*
  * get_mem_bw_imc:	Memory band width as reported by iMC counters
  * @cpu_no:		CPU number that the benchmark PID is binded to
@@ -306,26 +318,33 @@ static int initialize_mem_bw_imc(void)
 static int get_mem_bw_imc(int cpu_no, char *bw_report, float *bw_imc)
 {
 	float reads, writes, of_mul_read, of_mul_write;
-	int imc, j, ret;
+	int imc, ret;
+
+	for (imc = 0; imc < imcs; imc++) {
+		imc_counters_config[imc][READ].fd = -1;
+		imc_counters_config[imc][WRITE].fd = -1;
+	}
 
 	/* Start all iMC counters to log values (both read and write) */
 	reads = 0, writes = 0, of_mul_read = 1, of_mul_write = 1;
 	for (imc = 0; imc < imcs; imc++) {
-		for (j = 0; j < 2; j++) {
-			ret = open_perf_event(imc, cpu_no, j);
-			if (ret)
-				return -1;
-		}
-		for (j = 0; j < 2; j++)
-			membw_ioctl_perf_event_ioc_reset_enable(imc, j);
+		ret = open_perf_event(imc, cpu_no, READ);
+		if (ret)
+			goto close_fds;
+		ret = open_perf_event(imc, cpu_no, WRITE);
+		if (ret)
+			goto close_fds;
+
+		membw_ioctl_perf_event_ioc_reset_enable(imc, READ);
+		membw_ioctl_perf_event_ioc_reset_enable(imc, WRITE);
 	}
 
 	sleep(1);
 
 	/* Stop counters after a second to get results (both read and write) */
 	for (imc = 0; imc < imcs; imc++) {
-		for (j = 0; j < 2; j++)
-			membw_ioctl_perf_event_ioc_disable(imc, j);
+		membw_ioctl_perf_event_ioc_disable(imc, READ);
+		membw_ioctl_perf_event_ioc_disable(imc, WRITE);
 	}
 
 	/*
@@ -341,15 +360,13 @@ static int get_mem_bw_imc(int cpu_no, char *bw_report, float *bw_imc)
 		if (read(r->fd, &r->return_value,
 			 sizeof(struct membw_read_format)) == -1) {
 			ksft_perror("Couldn't get read b/w through iMC");
-
-			return -1;
+			goto close_fds;
 		}
 
 		if (read(w->fd, &w->return_value,
 			 sizeof(struct membw_read_format)) == -1) {
 			ksft_perror("Couldn't get write bw through iMC");
-
-			return -1;
+			goto close_fds;
 		}
 
 		__u64 r_time_enabled = r->return_value.time_enabled;
@@ -369,10 +386,7 @@ static int get_mem_bw_imc(int cpu_no, char *bw_report, float *bw_imc)
 		writes += w->return_value.value * of_mul_write * SCALE;
 	}
 
-	for (imc = 0; imc < imcs; imc++) {
-		close(imc_counters_config[imc][READ].fd);
-		close(imc_counters_config[imc][WRITE].fd);
-	}
+	perf_close_imc_mem_bw();
 
 	if (strcmp(bw_report, "reads") == 0) {
 		*bw_imc = reads;
@@ -386,6 +400,10 @@ static int get_mem_bw_imc(int cpu_no, char *bw_report, float *bw_imc)
 
 	*bw_imc = reads + writes;
 	return 0;
+
+close_fds:
+	perf_close_imc_mem_bw();
+	return -1;
 }
 
 void set_mbm_path(const char *ctrlgrp, const char *mongrp, int domain_id)
-- 
2.39.2