Extract split lock mitigation into common file

This reduces duplication of the split lock mitigation path.
Additionally, it allows extending the functionality of procsysctl into
also getting the split lock mitigation state.

common/common-splitlock.c

@@ -0,0 +1,64 @@
+/*
+
+Copyright (c) 2025, MithicSpirit
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+ * Redistributions of source code must retain the above copyright notice,
+   this list of conditions and the following disclaimer.
+ * Redistributions in binary form must reproduce the above copyright
+   notice, this list of conditions and the following disclaimer in the
+   documentation and/or other materials provided with the distribution.
+ * Neither the name of Feral Interactive nor the names of its contributors
+   may be used to endorse or promote products derived from this software
+   without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.
+
+ */
+
+#define _GNU_SOURCE
+
+#include "common-splitlock.h"
+#include "common-logging.h"
+
+/**
+ * Path for the split lock mitigation state
+ */
+const char *splitlock_path = "/proc/sys/kernel/split_lock_mitigate";
+
+/**
+ * Return the current split lock mitigation state
+ */
+long get_splitlock_state(void)
+{
+	FILE *f = fopen(splitlock_path, "r");
+	if (!f) {
+		LOG_ERROR("Failed to open file for read %s\n", splitlock_path);
+		return -1;
+	}
+
+	char contents[41] = { 0 };
+	long value = -1;
+
+	if (fread(contents, 1, sizeof contents - 1, f) > 0) {
+		value = strtol(contents, NULL, 10);
+	} else {
+		LOG_ERROR("Failed to read contents of %s\n", splitlock_path);
+	}
+	fclose(f);
+
+	return value;
+}

common/common-splitlock.h

@@ -0,0 +1,44 @@
+/*
+
+Copyright (c) 2025, MithicSpirit
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+ * Redistributions of source code must retain the above copyright notice,
+   this list of conditions and the following disclaimer.
+ * Redistributions in binary form must reproduce the above copyright
+   notice, this list of conditions and the following disclaimer in the
+   documentation and/or other materials provided with the distribution.
+ * Neither the name of Feral Interactive nor the names of its contributors
+   may be used to endorse or promote products derived from this software
+   without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.
+
+ */
+
+#pragma once
+
+#include <linux/limits.h>
+
+/**
+ * Path for the split lock mitagation state
+ */
+extern const char *splitlock_path;
+
+/**
+ * Get the current split lock mitigation state
+ */
+long get_splitlock_state(void);

common/meson.build

@@ -3,6 +3,7 @@ common_sources = [
     'common-logging.c',
     'common-governors.c',
     'common-profile.c',
+    'common-splitlock.c',
     'common-external.c',
     'common-helpers.c',
     'common-gpu.c',

daemon/gamemode-context.c

@@ -37,6 +37,7 @@ POSSIBILITY OF SUCH DAMAGE.
 #include "common-logging.h"
 #include "common-power.h"
 #include "common-profile.h"
+#include "common-splitlock.h"
 
 #include "gamemode.h"
 #include "gamemode-config.h"
@@ -220,25 +221,9 @@ void game_mode_context_destroy(GameModeContext *self)
 
 static void game_mode_store_splitlock(GameModeContext *self)
 {
-	FILE *f = fopen("/proc/sys/kernel/split_lock_mitigate", "r");
-	if (f == NULL) {
-		if (errno == ENOENT)
-			return;
-
-		LOG_ERROR("Couldn't open /proc/sys/kernel/split_lock_mitigate : %s\n", strerror(errno));
-		return;
-	}
-
-	char value_str[40];
-	if (fgets(value_str, sizeof value_str, f) == NULL) {
-		LOG_ERROR("Couldn't read from /proc/sys/kernel/split_lock_mitigate : %s\n",
-		          strerror(errno));
-		fclose(f);
-		return;
-	}
-	fclose(f);
-
-	self->initial_split_lock_mitigate = strtol(value_str, NULL, 10);
+	long initial_state = get_splitlock_state();
+	self->initial_split_lock_mitigate = initial_state;
+	LOG_MSG("split lock mitigation was initially set to [%ld]\n", initial_state);
 }
 
 static int game_mode_disable_splitlock(GameModeContext *self, bool disable)

util/procsysctl.c

@@ -27,8 +27,9 @@ POSSIBILITY OF SUCH DAMAGE.
 #define _GNU_SOURCE
 #include <unistd.h>
 #include "common-logging.h"
+#include "common-splitlock.h"
 
-static bool write_value(char *key, char *value)
+static bool write_value(const char *key, const char *value)
 {
 	FILE *f = fopen(key, "w");
 
@@ -58,7 +59,7 @@ int main(int argc, char *argv[])
 
 	if (argc == 3) {
 		if (strcmp(argv[1], "split_lock_mitigate") == 0) {
-			if (!write_value("/proc/sys/kernel/split_lock_mitigate", argv[2]))
+			if (!write_value(splitlock_path, argv[2]))
 				return EXIT_FAILURE;
 
 			return EXIT_SUCCESS;