Add kernel 5.15 for RPI4 support

root/target/linux/bcm27xx/patches-5.15/0043-cgroup-Disable-cgroup-memory-by-default.patch

@@ -0,0 +1,90 @@
+From 40a04a8163ad602e595998d97cd3278e85e7b398 Mon Sep 17 00:00:00 2001
+From: Phil Elwell <phil@raspberrypi.org>
+Date: Mon, 27 Nov 2017 17:14:54 +0000
+Subject: [PATCH 043/634] cgroup: Disable cgroup "memory" by default
+
+Some Raspberry Pis have limited RAM and most users won't use the
+cgroup memory support so it is disabled by default. Enable with:
+
+    cgroup_enable=memory
+
+See: https://github.com/raspberrypi/linux/issues/1950
+
+Signed-off-by: Phil Elwell <phil@raspberrypi.org>
+---
+ kernel/cgroup/cgroup.c | 38 ++++++++++++++++++++++++++++++++++++++
+ 1 file changed, 38 insertions(+)
+
+diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
+index d6ea872b23aa..db12e07ce531 100644
+--- a/kernel/cgroup/cgroup.c
++++ b/kernel/cgroup/cgroup.c
+@@ -5788,6 +5788,9 @@ int __init cgroup_init_early(void)
+ 	return 0;
+ }
+ 
++static u16 cgroup_enable_mask __initdata;
++static int __init cgroup_disable(char *str);
++
+ /**
+  * cgroup_init - cgroup initialization
+  *
+@@ -5826,6 +5829,12 @@ int __init cgroup_init(void)
+ 
+ 	mutex_unlock(&cgroup_mutex);
+ 
++	/*
++	 * Apply an implicit disable, knowing that an explicit enable will
++	 * prevent if from doing anything.
++	 */
++	cgroup_disable("memory");
++
+ 	for_each_subsys(ss, ssid) {
+ 		if (ss->early_init) {
+ 			struct cgroup_subsys_state *css =
+@@ -6409,6 +6418,10 @@ static int __init cgroup_disable(char *str)
+ 			    strcmp(token, ss->legacy_name))
+ 				continue;
+ 
++			/* An explicit cgroup_enable overrides a disable */
++			if (cgroup_enable_mask & (1 << i))
++				continue;
++
+ 			static_branch_disable(cgroup_subsys_enabled_key[i]);
+ 			pr_info("Disabling %s control group subsystem\n",
+ 				ss->name);
+@@ -6427,6 +6440,31 @@ static int __init cgroup_disable(char *str)
+ }
+ __setup("cgroup_disable=", cgroup_disable);
+ 
++static int __init cgroup_enable(char *str)
++{
++	struct cgroup_subsys *ss;
++	char *token;
++	int i;
++
++	while ((token = strsep(&str, ",")) != NULL) {
++		if (!*token)
++			continue;
++
++		for_each_subsys(ss, i) {
++			if (strcmp(token, ss->name) &&
++			    strcmp(token, ss->legacy_name))
++				continue;
++
++			cgroup_enable_mask |= 1 << i;
++			static_branch_enable(cgroup_subsys_enabled_key[i]);
++			pr_info("Enabling %s control group subsystem\n",
++				ss->name);
++		}
++	}
++	return 1;
++}
++__setup("cgroup_enable=", cgroup_enable);
++
+ void __init __weak enable_debug_cgroup(void) { }
+ 
+ static int __init enable_cgroup_debug(char *str)
+-- 
+2.33.1
+