ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 110 insertions, 0 deletions

diff --git a/arch/mips/ralink/rt3883.c b/arch/mips/ralink/rt3883.c
new file mode 100644
index 000000000..98aee412f
--- /dev/null
+++ b/arch/mips/ralink/rt3883.c
@@ -0,0 +1,110 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *
+ * Parts of this file are based on Ralink's 2.6.21 BSP
+ *
+ * Copyright (C) 2008 Imre Kaloz <kaloz@openwrt.org>
+ * Copyright (C) 2008-2011 Gabor Juhos <juhosg@openwrt.org>
+ * Copyright (C) 2013 John Crispin <john@phrozen.org>
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/sys_soc.h>
+
+#include <asm/mipsregs.h>
+#include <asm/mach-ralink/ralink_regs.h>
+#include <asm/mach-ralink/rt3883.h>
+
+#include "common.h"
+
+static struct ralink_soc_info *soc_info_ptr;
+
+static unsigned int __init rt3883_get_soc_name0(void)
+{
+	return __raw_readl(RT3883_SYSC_BASE + RT3883_SYSC_REG_CHIPID0_3);
+}
+
+static unsigned int __init rt3883_get_soc_name1(void)
+{
+	return __raw_readl(RT3883_SYSC_BASE + RT3883_SYSC_REG_CHIPID4_7);
+}
+
+static bool __init rt3883_soc_valid(void)
+{
+	if (rt3883_get_soc_name0() == RT3883_CHIP_NAME0 &&
+	    rt3883_get_soc_name1() == RT3883_CHIP_NAME1)
+		return true;
+	else
+		return false;
+}
+
+static const char __init *rt3883_get_soc_name(void)
+{
+	if (rt3883_soc_valid())
+		return "RT3883";
+	else
+		return "invalid";
+}
+
+static unsigned int __init rt3883_get_soc_id(void)
+{
+	return __raw_readl(RT3883_SYSC_BASE + RT3883_SYSC_REG_REVID);
+}
+
+static unsigned int __init rt3883_get_soc_ver(void)
+{
+	return (rt3883_get_soc_id() >> RT3883_REVID_VER_ID_SHIFT) & RT3883_REVID_VER_ID_MASK;
+}
+
+static unsigned int __init rt3883_get_soc_rev(void)
+{
+	return (rt3883_get_soc_id() & RT3883_REVID_ECO_ID_MASK);
+}
+
+static int __init rt3883_soc_dev_init(void)
+{
+	struct soc_device *soc_dev;
+	struct soc_device_attribute *soc_dev_attr;
+
+	soc_dev_attr = kzalloc_obj(*soc_dev_attr);
+	if (!soc_dev_attr)
+		return -ENOMEM;
+
+	soc_dev_attr->family = "Ralink";
+	soc_dev_attr->soc_id = rt3883_get_soc_name();
+
+	soc_dev_attr->data = soc_info_ptr;
+
+	soc_dev = soc_device_register(soc_dev_attr);
+	if (IS_ERR(soc_dev)) {
+		kfree(soc_dev_attr);
+		return PTR_ERR(soc_dev);
+	}
+
+	return 0;
+}
+device_initcall(rt3883_soc_dev_init);
+
+void __init prom_soc_init(struct ralink_soc_info *soc_info)
+{
+	if (rt3883_soc_valid())
+		soc_info->compatible = "ralink,rt3883-soc";
+	else
+		panic("rt3883: unknown SoC, n0:%08x n1:%08x",
+		      rt3883_get_soc_name0(), rt3883_get_soc_name1());
+
+	snprintf(soc_info->sys_type, RAMIPS_SYS_TYPE_LEN,
+		"Ralink %s ver:%u eco:%u",
+		rt3883_get_soc_name(),
+		rt3883_get_soc_ver(),
+		rt3883_get_soc_rev());
+
+	soc_info->mem_base = RT3883_SDRAM_BASE;
+	soc_info->mem_size_min = RT3883_MEM_SIZE_MIN;
+	soc_info->mem_size_max = RT3883_MEM_SIZE_MAX;
+
+	ralink_soc = RT3883_SOC;
+	soc_info_ptr = soc_info;
+}