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, 65 insertions, 0 deletions

diff --git a/drivers/media/dvb-frontends/dvb-pll.h b/drivers/media/dvb-frontends/dvb-pll.h
new file mode 100644
index 000000000..718388887
--- /dev/null
+++ b/drivers/media/dvb-frontends/dvb-pll.h
@@ -0,0 +1,65 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * descriptions + helper functions for simple dvb plls.
+ */
+
+#ifndef __DVB_PLL_H__
+#define __DVB_PLL_H__
+
+#include <linux/i2c.h>
+#include <media/dvb_frontend.h>
+
+#define DVB_PLL_UNDEFINED               0
+#define DVB_PLL_THOMSON_DTT7579         1
+#define DVB_PLL_THOMSON_DTT759X         2
+#define DVB_PLL_LG_Z201                 3
+#define DVB_PLL_UNKNOWN_1               4
+#define DVB_PLL_TUA6010XS               5
+#define DVB_PLL_ENV57H1XD5              6
+#define DVB_PLL_TUA6034                 7
+#define DVB_PLL_TDA665X                 8
+#define DVB_PLL_TDED4                   9
+#define DVB_PLL_TDHU2                  10
+#define DVB_PLL_SAMSUNG_TBMV           11
+#define DVB_PLL_PHILIPS_SD1878_TDA8261 12
+#define DVB_PLL_OPERA1                 13
+#define DVB_PLL_SAMSUNG_DTOS403IH102A  14
+#define DVB_PLL_SAMSUNG_TDTC9251DH0    15
+#define DVB_PLL_SAMSUNG_TBDU18132      16
+#define DVB_PLL_SAMSUNG_TBMU24112      17
+#define DVB_PLL_TDEE4		       18
+#define DVB_PLL_THOMSON_DTT7520X       19
+#define DVB_PLL_TUA6034_FRIIO          20
+#define DVB_PLL_TDA665X_EARTH_PT1      21
+
+struct dvb_pll_config {
+	struct dvb_frontend *fe;
+};
+
+#if IS_REACHABLE(CONFIG_DVB_PLL)
+/**
+ * dvb_pll_attach - Attach a dvb-pll to the supplied frontend structure.
+ *
+ * @fe: Frontend to attach to.
+ * @pll_addr: i2c address of the PLL (if used).
+ * @i2c: i2c adapter to use (set to NULL if not used).
+ * @pll_desc_id: dvb_pll_desc to use.
+ *
+ * return: Frontend pointer on success, NULL on failure
+ */
+extern struct dvb_frontend *dvb_pll_attach(struct dvb_frontend *fe,
+					   int pll_addr,
+					   struct i2c_adapter *i2c,
+					   unsigned int pll_desc_id);
+#else
+static inline struct dvb_frontend *dvb_pll_attach(struct dvb_frontend *fe,
+					   int pll_addr,
+					   struct i2c_adapter *i2c,
+					   unsigned int pll_desc_id)
+{
+	printk(KERN_WARNING "%s: driver disabled by Kconfig\n", __func__);
+	return NULL;
+}
+#endif
+
+#endif