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, 232 insertions, 0 deletions

diff --git a/drivers/mtd/tests/stresstest.c b/drivers/mtd/tests/stresstest.c
new file mode 100644
index 000000000..944f960a4
--- /dev/null
+++ b/drivers/mtd/tests/stresstest.c
@@ -0,0 +1,232 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2006-2008 Nokia Corporation
+ *
+ * Test random reads, writes and erases on MTD device.
+ *
+ * Author: Adrian Hunter <ext-adrian.hunter@nokia.com>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/err.h>
+#include <linux/mtd/mtd.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/vmalloc.h>
+#include <linux/random.h>
+
+#include "mtd_test.h"
+
+static int dev = -EINVAL;
+module_param(dev, int, S_IRUGO);
+MODULE_PARM_DESC(dev, "MTD device number to use");
+
+static int count = 10000;
+module_param(count, int, S_IRUGO);
+MODULE_PARM_DESC(count, "Number of operations to do (default is 10000)");
+
+static struct mtd_info *mtd;
+static unsigned char *writebuf;
+static unsigned char *readbuf;
+static unsigned char *bbt;
+static int *offsets;
+
+static int pgsize;
+static int bufsize;
+static int ebcnt;
+static int pgcnt;
+
+static int rand_eb(void)
+{
+	unsigned int eb;
+
+again:
+	/* Read or write up 2 eraseblocks at a time - hence 'ebcnt - 1' */
+	eb = get_random_u32_below(ebcnt - 1);
+	if (bbt[eb])
+		goto again;
+	return eb;
+}
+
+static int rand_offs(void)
+{
+	return get_random_u32_below(bufsize);
+}
+
+static int rand_len(int offs)
+{
+	return get_random_u32_below(bufsize - offs);
+}
+
+static int do_read(void)
+{
+	int eb = rand_eb();
+	int offs = rand_offs();
+	int len = rand_len(offs);
+	loff_t addr;
+
+	if (bbt[eb + 1]) {
+		if (offs >= mtd->erasesize)
+			offs -= mtd->erasesize;
+		if (offs + len > mtd->erasesize)
+			len = mtd->erasesize - offs;
+	}
+	addr = (loff_t)eb * mtd->erasesize + offs;
+	return mtdtest_read(mtd, addr, len, readbuf);
+}
+
+static int do_write(void)
+{
+	int eb = rand_eb(), offs, err, len;
+	loff_t addr;
+
+	offs = offsets[eb];
+	if (offs >= mtd->erasesize) {
+		err = mtdtest_erase_eraseblock(mtd, eb);
+		if (err)
+			return err;
+		offs = offsets[eb] = 0;
+	}
+	len = rand_len(offs);
+	len = ((len + pgsize - 1) / pgsize) * pgsize;
+	if (offs + len > mtd->erasesize) {
+		if (bbt[eb + 1])
+			len = mtd->erasesize - offs;
+		else {
+			err = mtdtest_erase_eraseblock(mtd, eb + 1);
+			if (err)
+				return err;
+			offsets[eb + 1] = 0;
+		}
+	}
+	addr = (loff_t)eb * mtd->erasesize + offs;
+	err = mtdtest_write(mtd, addr, len, writebuf);
+	if (unlikely(err))
+		return err;
+	offs += len;
+	while (offs > mtd->erasesize) {
+		offsets[eb++] = mtd->erasesize;
+		offs -= mtd->erasesize;
+	}
+	offsets[eb] = offs;
+	return 0;
+}
+
+static int do_operation(void)
+{
+	if (get_random_u32_below(2))
+		return do_read();
+	else
+		return do_write();
+}
+
+static int __init mtd_stresstest_init(void)
+{
+	int err;
+	int i, op;
+	uint64_t tmp;
+
+	printk(KERN_INFO "\n");
+	printk(KERN_INFO "=================================================\n");
+
+	if (dev < 0) {
+		pr_info("Please specify a valid mtd-device via module parameter\n");
+		pr_crit("CAREFUL: This test wipes all data on the specified MTD device!\n");
+		return -EINVAL;
+	}
+
+	pr_info("MTD device: %d\n", dev);
+
+	mtd = get_mtd_device(NULL, dev);
+	if (IS_ERR(mtd)) {
+		err = PTR_ERR(mtd);
+		pr_err("error: cannot get MTD device\n");
+		return err;
+	}
+
+	if (mtd->writesize == 1) {
+		pr_info("not NAND flash, assume page size is 512 "
+		       "bytes.\n");
+		pgsize = 512;
+	} else
+		pgsize = mtd->writesize;
+
+	tmp = mtd->size;
+	do_div(tmp, mtd->erasesize);
+	ebcnt = tmp;
+	pgcnt = mtd->erasesize / pgsize;
+
+	pr_info("MTD device size %llu, eraseblock size %u, "
+	       "page size %u, count of eraseblocks %u, pages per "
+	       "eraseblock %u, OOB size %u\n",
+	       (unsigned long long)mtd->size, mtd->erasesize,
+	       pgsize, ebcnt, pgcnt, mtd->oobsize);
+
+	if (ebcnt < 2) {
+		pr_err("error: need at least 2 eraseblocks\n");
+		err = -ENOSPC;
+		goto out_put_mtd;
+	}
+
+	/* Read or write up 2 eraseblocks at a time */
+	bufsize = mtd->erasesize * 2;
+
+	err = -ENOMEM;
+	readbuf = vmalloc(bufsize);
+	writebuf = vmalloc(bufsize);
+	offsets = kmalloc_objs(int, ebcnt);
+	if (!readbuf || !writebuf || !offsets)
+		goto out;
+	for (i = 0; i < ebcnt; i++)
+		offsets[i] = mtd->erasesize;
+	get_random_bytes(writebuf, bufsize);
+
+	bbt = kzalloc(ebcnt, GFP_KERNEL);
+	if (!bbt)
+		goto out;
+	err = mtdtest_scan_for_bad_eraseblocks(mtd, bbt, 0, ebcnt);
+	if (err)
+		goto out;
+
+	/* Do operations */
+	pr_info("doing operations\n");
+	for (op = 0; op < count; op++) {
+		if ((op & 1023) == 0)
+			pr_info("%d operations done\n", op);
+		err = do_operation();
+		if (err)
+			goto out;
+
+		err = mtdtest_relax();
+		if (err)
+			goto out;
+	}
+	pr_info("finished, %d operations done\n", op);
+
+out:
+	kfree(offsets);
+	kfree(bbt);
+	vfree(writebuf);
+	vfree(readbuf);
+out_put_mtd:
+	put_mtd_device(mtd);
+	if (err)
+		pr_info("error %d occurred\n", err);
+	printk(KERN_INFO "=================================================\n");
+	return err;
+}
+module_init(mtd_stresstest_init);
+
+static void __exit mtd_stresstest_exit(void)
+{
+	return;
+}
+module_exit(mtd_stresstest_exit);
+
+MODULE_DESCRIPTION("Stress test module");
+MODULE_AUTHOR("Adrian Hunter");
+MODULE_LICENSE("GPL");