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, 172 insertions, 0 deletions

diff --git a/drivers/clk/ti/clockdomain.c b/drivers/clk/ti/clockdomain.c
new file mode 100644
index 000000000..c897ad7e6
--- /dev/null
+++ b/drivers/clk/ti/clockdomain.c
@@ -0,0 +1,172 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * OMAP clockdomain support
+ *
+ * Copyright (C) 2013 Texas Instruments, Inc.
+ *
+ * Tero Kristo <t-kristo@ti.com>
+ */
+
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/clk/ti.h>
+
+#include "clock.h"
+
+#undef pr_fmt
+#define pr_fmt(fmt) "%s: " fmt, __func__
+
+/**
+ * omap2_clkops_enable_clkdm - increment usecount on clkdm of @hw
+ * @hw: struct clk_hw * of the clock being enabled
+ *
+ * Increment the usecount of the clockdomain of the clock pointed to
+ * by @hw; if the usecount is 1, the clockdomain will be "enabled."
+ * Only needed for clocks that don't use omap2_dflt_clk_enable() as
+ * their enable function pointer.  Passes along the return value of
+ * clkdm_clk_enable(), -EINVAL if @hw is not associated with a
+ * clockdomain, or 0 if clock framework-based clockdomain control is
+ * not implemented.
+ */
+int omap2_clkops_enable_clkdm(struct clk_hw *hw)
+{
+	struct clk_hw_omap *clk;
+	int ret = 0;
+
+	clk = to_clk_hw_omap(hw);
+
+	if (unlikely(!clk->clkdm)) {
+		pr_err("%s: %s: no clkdm set ?!\n", __func__,
+		       clk_hw_get_name(hw));
+		return -EINVAL;
+	}
+
+	if (ti_clk_get_features()->flags & TI_CLK_DISABLE_CLKDM_CONTROL) {
+		pr_err("%s: %s: clkfw-based clockdomain control disabled ?!\n",
+		       __func__, clk_hw_get_name(hw));
+		return 0;
+	}
+
+	ret = ti_clk_ll_ops->clkdm_clk_enable(clk->clkdm, hw->clk);
+	WARN(ret, "%s: could not enable %s's clockdomain %s: %d\n",
+	     __func__, clk_hw_get_name(hw), clk->clkdm_name, ret);
+
+	return ret;
+}
+
+/**
+ * omap2_clkops_disable_clkdm - decrement usecount on clkdm of @hw
+ * @hw: struct clk_hw * of the clock being disabled
+ *
+ * Decrement the usecount of the clockdomain of the clock pointed to
+ * by @hw; if the usecount is 0, the clockdomain will be "disabled."
+ * Only needed for clocks that don't use omap2_dflt_clk_disable() as their
+ * disable function pointer.  No return value.
+ */
+void omap2_clkops_disable_clkdm(struct clk_hw *hw)
+{
+	struct clk_hw_omap *clk;
+
+	clk = to_clk_hw_omap(hw);
+
+	if (unlikely(!clk->clkdm)) {
+		pr_err("%s: %s: no clkdm set ?!\n", __func__,
+		       clk_hw_get_name(hw));
+		return;
+	}
+
+	if (ti_clk_get_features()->flags & TI_CLK_DISABLE_CLKDM_CONTROL) {
+		pr_err("%s: %s: clkfw-based clockdomain control disabled ?!\n",
+		       __func__, clk_hw_get_name(hw));
+		return;
+	}
+
+	ti_clk_ll_ops->clkdm_clk_disable(clk->clkdm, hw->clk);
+}
+
+/**
+ * omap2_init_clk_clkdm - look up a clockdomain name, store pointer in clk
+ * @hw: Pointer to clk_hw_omap used to obtain OMAP clock struct ptr to use
+ *
+ * Convert a clockdomain name stored in a struct clk 'clk' into a
+ * clockdomain pointer, and save it into the struct clk.  Intended to be
+ * called during clk_register(). Returns 0 on success, -EERROR otherwise.
+ */
+int omap2_init_clk_clkdm(struct clk_hw *hw)
+{
+	struct clk_hw_omap *clk = to_clk_hw_omap(hw);
+	struct clockdomain *clkdm;
+	const char *clk_name;
+
+	if (!clk->clkdm_name)
+		return 0;
+
+	clk_name = __clk_get_name(hw->clk);
+
+	clkdm = ti_clk_ll_ops->clkdm_lookup(clk->clkdm_name);
+	if (clkdm) {
+		pr_debug("clock: associated clk %s to clkdm %s\n",
+			 clk_name, clk->clkdm_name);
+		clk->clkdm = clkdm;
+	} else {
+		pr_debug("clock: could not associate clk %s to clkdm %s\n",
+			 clk_name, clk->clkdm_name);
+	}
+
+	return 0;
+}
+
+static void __init of_ti_clockdomain_setup(struct device_node *node)
+{
+	struct clk *clk;
+	struct clk_hw *clk_hw;
+	const char *clkdm_name = ti_dt_clk_name(node);
+	int i;
+	unsigned int num_clks;
+
+	num_clks = of_clk_get_parent_count(node);
+
+	for (i = 0; i < num_clks; i++) {
+		clk = of_clk_get(node, i);
+		if (IS_ERR(clk)) {
+			pr_err("%s: Failed get %pOF' clock nr %d (%ld)\n",
+			       __func__, node, i, PTR_ERR(clk));
+			continue;
+		}
+		clk_hw = __clk_get_hw(clk);
+		if (!omap2_clk_is_hw_omap(clk_hw)) {
+			pr_warn("can't setup clkdm for basic clk %s\n",
+				__clk_get_name(clk));
+			clk_put(clk);
+			continue;
+		}
+		to_clk_hw_omap(clk_hw)->clkdm_name = clkdm_name;
+		omap2_init_clk_clkdm(clk_hw);
+		clk_put(clk);
+	}
+}
+
+static const struct of_device_id ti_clkdm_match_table[] __initconst = {
+	{ .compatible = "ti,clockdomain" },
+	{ }
+};
+
+/**
+ * ti_dt_clockdomains_setup - setup device tree clockdomains
+ *
+ * Initializes clockdomain nodes for a SoC. This parses through all the
+ * nodes with compatible = "ti,clockdomain", and add the clockdomain
+ * info for all the clocks listed under these. This function shall be
+ * called after rest of the DT clock init has completed and all
+ * clock nodes have been registered.
+ */
+void __init ti_dt_clockdomains_setup(void)
+{
+	struct device_node *np;
+	for_each_matching_node(np, ti_clkdm_match_table) {
+		of_ti_clockdomain_setup(np);
+	}
+}