tools/rv: Allow rv list to filter for container

Add possibility to supply the container name to rv list:

  # rv list sched
  mon1
  mon2
  mon3

This lists only monitors in sched, without indentation.
Supplying -h, any option (string starting with -) or more than 1
argument will still print the usage.
Passing a non-existent container prints nothing and passing no container
continues to print all monitors, showing indentation for nested
monitors, reported after their container.

Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Link: https://lore.kernel.org/20250305140406.350227-10-gmonaco@redhat.com
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

tools/verification/rv/include/in_kernel.h

@@ -1,3 +1,3 @@
 // SPDX-License-Identifier: GPL-2.0
-int ikm_list_monitors(void);
+int ikm_list_monitors(char *container);
 int ikm_run_monitor(char *monitor, int argc, char **argv);

tools/verification/rv/src/in_kernel.c

@@ -180,19 +180,25 @@ static char *ikm_read_desc(char *monitor_name)
 /*
  * ikm_fill_monitor_definition - fill monitor's definition
  *
- * Returns -1 on error, 0 otherwise.
+ * Returns -1 on error, 1 if the monitor does not belong in the container, 0 otherwise.
+ * container can be NULL
  */
-static int ikm_fill_monitor_definition(char *name, struct monitor *ikm)
+static int ikm_fill_monitor_definition(char *name, struct monitor *ikm, char *container)
 {
 	int enabled;
 	char *desc, *nested_name;
 
 	nested_name = strstr(name, ":");
 	if (nested_name) {
+		/* it belongs in container if it starts with "container:" */
+		if (container && strstr(name, container) != name)
+			return 1;
 		*nested_name = '/';
 		++nested_name;
 		ikm->nested = 1;
 	} else {
+		if (container)
+			return 1;
 		nested_name = name;
 		ikm->nested = 0;
 	}
@@ -328,12 +334,12 @@ static int ikm_has_id(char *monitor_name)
  *
  * Returns 0 on success, -1 otherwise.
  */
-int ikm_list_monitors(void)
+int ikm_list_monitors(char *container)
 {
 	char *available_monitors;
 	struct monitor ikm = {0};
 	char *curr, *next;
-	int retval;
+	int retval, list_monitor = 0;
 
 	available_monitors = tracefs_instance_file_read(NULL, "rv/available_monitors", NULL);
 
@@ -347,17 +353,29 @@ int ikm_list_monitors(void)
 		next = strstr(curr, "\n");
 		*next = '\0';
 
-		retval = ikm_fill_monitor_definition(curr, &ikm);
-		if (retval)
+		retval = ikm_fill_monitor_definition(curr, &ikm, container);
+		if (retval < 0)
 			err_msg("ikm: error reading %d in kernel monitor, skipping\n", curr);
 
-		printf("%s%-*s %s %s\n", ikm.nested ? " - " : "",
-		       ikm.nested ? MAX_DA_NAME_LEN - 3 : MAX_DA_NAME_LEN,
-		       ikm.name, ikm.desc, ikm.enabled ? "[ON]" : "[OFF]");
+		if (!retval) {
+			int indent = ikm.nested && !container;
+
+			list_monitor = 1;
+			printf("%s%-*s %s %s\n", indent ? " - " : "",
+			       indent ? MAX_DA_NAME_LEN - 3 : MAX_DA_NAME_LEN,
+			       ikm.name, ikm.desc, ikm.enabled ? "[ON]" : "[OFF]");
+		}
 		curr = ++next;
 
 	} while (strlen(curr));
 
+	if (!list_monitor) {
+		if (container)
+			printf("-- No monitor found in container %s --\n", container);
+		else
+			printf("-- No monitor found --\n");
+	}
+
 	free(available_monitors);
 
 	return 0;

tools/verification/rv/src/rv.c

@@ -41,30 +41,42 @@ static void rv_list(int argc, char **argv)
 {
 	static const char *const usage[] = {
 		"",
-		"  usage: rv list [-h]",
+		"  usage: rv list [-h] [container]",
 		"",
 		"	list all available monitors",
 		"",
 		"	-h/--help: print this menu",
+		"",
+		"	[container]: list only monitors in this container",
 		NULL,
 	};
-	int i;
-
-	if (argc > 1) {
+	int i, print_help = 0, retval = 0;
+	char *container = NULL;
+
+	if (argc == 2) {
+		if (!strcmp(argv[1], "-h") || !strcmp(argv[1], "--help")) {
+			print_help = 1;
+			retval = 0;
+		} else if (argv[1][0] == '-') {
+			/* assume invalid option */
+			print_help = 1;
+			retval = 1;
+		} else
+			container = argv[1];
+	} else if (argc > 2) {
+		/* more than 2 is always usage */
+		print_help = 1;
+		retval = 1;
+	}
+	if (print_help) {
 		fprintf(stderr, "rv version %s\n", VERSION);
-
-		/* more than 1 is always usage */
 		for (i = 0; usage[i]; i++)
 			fprintf(stderr, "%s\n", usage[i]);
-
-		/* but only -h is valid */
-		if (!strcmp(argv[1], "-h") || !strcmp(argv[1], "--help"))
-			exit(0);
-		else
-			exit(1);
+		exit(retval);
 	}
 
-	ikm_list_monitors();
+	ikm_list_monitors(container);
+
 	exit(0);
 }