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, 131 insertions, 0 deletions

diff --git a/drivers/comedi/range.c b/drivers/comedi/range.c
new file mode 100644
index 000000000..5b8f66236
--- /dev/null
+++ b/drivers/comedi/range.c
@@ -0,0 +1,131 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * comedi/range.c
+ * comedi routines for voltage ranges
+ *
+ * COMEDI - Linux Control and Measurement Device Interface
+ * Copyright (C) 1997-8 David A. Schleef <ds@schleef.org>
+ */
+
+#include <linux/uaccess.h>
+#include <linux/comedi/comedidev.h>
+#include "comedi_internal.h"
+
+const struct comedi_lrange range_bipolar10 = { 1, {BIP_RANGE(10)} };
+EXPORT_SYMBOL_GPL(range_bipolar10);
+const struct comedi_lrange range_bipolar5 = { 1, {BIP_RANGE(5)} };
+EXPORT_SYMBOL_GPL(range_bipolar5);
+const struct comedi_lrange range_bipolar2_5 = { 1, {BIP_RANGE(2.5)} };
+EXPORT_SYMBOL_GPL(range_bipolar2_5);
+const struct comedi_lrange range_unipolar10 = { 1, {UNI_RANGE(10)} };
+EXPORT_SYMBOL_GPL(range_unipolar10);
+const struct comedi_lrange range_unipolar5 = { 1, {UNI_RANGE(5)} };
+EXPORT_SYMBOL_GPL(range_unipolar5);
+const struct comedi_lrange range_unipolar2_5 = { 1, {UNI_RANGE(2.5)} };
+EXPORT_SYMBOL_GPL(range_unipolar2_5);
+const struct comedi_lrange range_0_20mA = { 1, {RANGE_mA(0, 20)} };
+EXPORT_SYMBOL_GPL(range_0_20mA);
+const struct comedi_lrange range_4_20mA = { 1, {RANGE_mA(4, 20)} };
+EXPORT_SYMBOL_GPL(range_4_20mA);
+const struct comedi_lrange range_0_32mA = { 1, {RANGE_mA(0, 32)} };
+EXPORT_SYMBOL_GPL(range_0_32mA);
+const struct comedi_lrange range_unknown = { 1, {{0, 1000000, UNIT_none} } };
+EXPORT_SYMBOL_GPL(range_unknown);
+
+/*
+ * COMEDI_RANGEINFO ioctl
+ * range information
+ *
+ * arg:
+ *	pointer to comedi_rangeinfo structure
+ *
+ * reads:
+ *	comedi_rangeinfo structure
+ *
+ * writes:
+ *	array of comedi_krange structures to rangeinfo->range_ptr pointer
+ */
+int do_rangeinfo_ioctl(struct comedi_device *dev,
+		       struct comedi_rangeinfo *it)
+{
+	int subd, chan;
+	const struct comedi_lrange *lr;
+	struct comedi_subdevice *s;
+
+	subd = (it->range_type >> 24) & 0xff;
+	chan = (it->range_type >> 16) & 0xff;
+
+	if (!dev->attached)
+		return -EINVAL;
+	if (subd >= dev->n_subdevices)
+		return -EINVAL;
+	s = &dev->subdevices[subd];
+	if (s->range_table) {
+		lr = s->range_table;
+	} else if (s->range_table_list) {
+		if (chan >= s->n_chan)
+			return -EINVAL;
+		lr = s->range_table_list[chan];
+	} else {
+		return -EINVAL;
+	}
+
+	if (RANGE_LENGTH(it->range_type) != lr->length) {
+		dev_dbg(dev->class_dev,
+			"wrong length %d should be %d (0x%08x)\n",
+			RANGE_LENGTH(it->range_type),
+			lr->length, it->range_type);
+		return -EINVAL;
+	}
+
+	if (copy_to_user(it->range_ptr, lr->range,
+			 sizeof(struct comedi_krange) * lr->length))
+		return -EFAULT;
+
+	return 0;
+}
+
+/**
+ * comedi_check_chanlist() - Validate each element in a chanlist.
+ * @s: comedi_subdevice struct
+ * @n: number of elements in the chanlist
+ * @chanlist: the chanlist to validate
+ *
+ * Each element consists of a channel number, a range index, an analog
+ * reference type and some flags, all packed into an unsigned int.
+ *
+ * This checks that the channel number and range index are supported by
+ * the comedi subdevice.  It does not check whether the analog reference
+ * type and the flags are supported.  Drivers that care should check those
+ * themselves.
+ *
+ * Return: %0 if all @chanlist elements are valid (success),
+ *         %-EINVAL if one or more elements are invalid.
+ */
+int comedi_check_chanlist(struct comedi_subdevice *s, int n,
+			  unsigned int *chanlist)
+{
+	struct comedi_device *dev = s->device;
+	unsigned int chanspec;
+	int chan, range_len, i;
+
+	for (i = 0; i < n; i++) {
+		chanspec = chanlist[i];
+		chan = CR_CHAN(chanspec);
+		if (s->range_table)
+			range_len = s->range_table->length;
+		else if (s->range_table_list && chan < s->n_chan)
+			range_len = s->range_table_list[chan]->length;
+		else
+			range_len = 0;
+		if (chan >= s->n_chan ||
+		    CR_RANGE(chanspec) >= range_len) {
+			dev_warn(dev->class_dev,
+				 "bad chanlist[%d]=0x%08x chan=%d range length=%d\n",
+				 i, chanspec, chan, range_len);
+			return -EINVAL;
+		}
+	}
+	return 0;
+}
+EXPORT_SYMBOL_GPL(comedi_check_chanlist);