From: Michael Tremer <michael.tremer@ipfire.org>
Date: Sat, 14 Dec 2024 13:21:06 +0000 (+0000)
Subject: cgroups: Keep bitmap of enabled controllers
X-Git-Tag: 0.9.30~728
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6179442c7016c1af2a7fa6e3533d2c64ee46ab67;p=pakfire.git

cgroups: Keep bitmap of enabled controllers

This helps us to perform fewer operations when we create a cgroup.

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>
---

diff --git a/src/libpakfire/cgroup.c b/src/libpakfire/cgroup.c
index 5b4900973..b318eaf88 100644
--- a/src/libpakfire/cgroup.c
+++ b/src/libpakfire/cgroup.c
@@ -71,6 +71,9 @@ struct pakfire_cgroup {
 	char name[NAME_MAX];
 	char path[PATH_MAX];
 
+	// Controllers
+	unsigned int controllers;
+
 	// File descriptor to cgroup
 	int fd;
 
@@ -263,19 +266,87 @@ ERROR:
 	return r;
 }
 
+static int pakfire_cgroup_controller_from_string(const char* name) {
+	if (!name)
+		return 0;
+
+	if (strcmp(name, "cpu") == 0)
+		return PAKFIRE_CGROUP_CONTROLLER_CPU;
+
+	else if (strcmp(name, "memory") == 0)
+		return PAKFIRE_CGROUP_CONTROLLER_MEMORY;
+
+	else if (strcmp(name, "pids") == 0)
+		return PAKFIRE_CGROUP_CONTROLLER_PIDS;
+
+	else if (strcmp(name, "io") == 0)
+		return PAKFIRE_CGROUP_CONTROLLER_IO;
+
+	return 0;
+}
+
+static const char* pakfire_cgroup_controller_name(int controller) {
+	switch (controller) {
+		case PAKFIRE_CGROUP_CONTROLLER_CPU:
+			return "cpu";
+
+		case PAKFIRE_CGROUP_CONTROLLER_MEMORY:
+			return "memory";
+
+		case PAKFIRE_CGROUP_CONTROLLER_PIDS:
+			return "pids";
+
+		case PAKFIRE_CGROUP_CONTROLLER_IO:
+			return "io";
+	}
+
+	return NULL;
+}
+
+static int pakfire_cgroup_read_controllers(struct pakfire_cgroup* cgroup) {
+	char buffer[4096];
+	char* p = NULL;
+	int r;
+
+	// Read the data into a buffer
+	r = pakfire_cgroup_read(cgroup, "cgroup.subtree_control", buffer, sizeof(buffer));
+	if (r < 0)
+		return r;
+
+	// Tokenize the string
+	char* token = strtok_r(buffer, " ", &p);
+
+	while (token) {
+		cgroup->controllers |= pakfire_cgroup_controller_from_string(token);
+
+		// Move on to the next token
+		token = strtok_r(NULL, " ", &p);
+	}
+
+	return 0;
+}
+
 /*
 	Enables a cgroup controller.
 */
-static int pakfire_cgroup_enable_controller(struct pakfire_cgroup* cgroup, const char* name) {
+static int pakfire_cgroup_enable_controller(struct pakfire_cgroup* cgroup, int controller) {
 	int r;
 
 	// Ensure this controller is enabled on the parent, too
 	if (cgroup->parent) {
-		r = pakfire_cgroup_enable_controller(cgroup->parent, name);
+		r = pakfire_cgroup_enable_controller(cgroup->parent, controller);
 		if (r < 0)
 			return r;
 	}
 
+	const char* name = pakfire_cgroup_controller_name(controller);
+
+	// Check if we know this controller
+	if (!name) {
+		ERROR(cgroup->ctx, "Cannot enable unknown controller\n");
+		return -ENOTSUP;
+	}
+
 	// Try to enable the controller
 	r = pakfire_cgroup_write(cgroup, "cgroup.subtree_control", "+%s", name);
 	if (r < 0) {
@@ -291,13 +362,17 @@ static int pakfire_cgroup_enable_controller(struct pakfire_cgroup* cgroup, const
 	Enables all controllers that we need.
 */
 static int pakfire_cgroup_enable_controllers(struct pakfire_cgroup* cgroup) {
-	static const char* controllers[] = {
-		"cpu", "memory", "pids", "io", NULL,
+	static const int controllers[] = {
+		PAKFIRE_CGROUP_CONTROLLER_CPU,
+		PAKFIRE_CGROUP_CONTROLLER_MEMORY,
+		PAKFIRE_CGROUP_CONTROLLER_PIDS,
+		PAKFIRE_CGROUP_CONTROLLER_IO,
+		0,
 	};
 	int r;
 
 	// Enable all controllers
-	for (const char** controller = controllers; *controller; controller++) {
+	for (int* controller = controllers; *controller; controller++) {
 		r = pakfire_cgroup_enable_controller(cgroup, *controller);
 		if (r < 0)
 			return r;
@@ -354,6 +429,11 @@ static int pakfire_cgroup_open(struct pakfire_cgroup** cgroup,
 	if (r < 0)
 		goto ERROR;
 
+	// Read controllers
+	r = pakfire_cgroup_read_controllers(c);
+	if (r < 0)
+		goto ERROR;
+
 	// Enable all controllers
 	r = pakfire_cgroup_enable_controllers(c);
 	if (r < 0)
diff --git a/src/libpakfire/include/pakfire/cgroup.h b/src/libpakfire/include/pakfire/cgroup.h
index b4100a48b..6f86fbdca 100644
--- a/src/libpakfire/include/pakfire/cgroup.h
+++ b/src/libpakfire/include/pakfire/cgroup.h
@@ -25,6 +25,13 @@
 
 #include <pakfire/ctx.h>
 
+enum pakfire_cgroup_controllers {
+	PAKFIRE_CGROUP_CONTROLLER_CPU     = (1 << 0),
+	PAKFIRE_CGROUP_CONTROLLER_MEMORY  = (1 << 1),
+	PAKFIRE_CGROUP_CONTROLLER_PIDS    = (1 << 2),
+	PAKFIRE_CGROUP_CONTROLLER_IO      = (1 << 3),
+};
+
 struct pakfire_cgroup;
 
 struct pakfire_cgroup_stats {