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, 87 insertions, 0 deletions

diff --git a/crypto/842.c b/crypto/842.c
new file mode 100644
index 000000000..4007e87be
--- /dev/null
+++ b/crypto/842.c
@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Cryptographic API for the 842 software compression algorithm.
+ *
+ * Copyright (C) IBM Corporation, 2011-2015
+ *
+ * Original Authors: Robert Jennings <rcj@linux.vnet.ibm.com>
+ *                   Seth Jennings <sjenning@linux.vnet.ibm.com>
+ *
+ * Rewrite: Dan Streetman <ddstreet@ieee.org>
+ *
+ * This is the software implementation of compression and decompression using
+ * the 842 format.  This uses the software 842 library at lib/842/ which is
+ * only a reference implementation, and is very, very slow as compared to other
+ * software compressors.  You probably do not want to use this software
+ * compression.  If you have access to the PowerPC 842 compression hardware, you
+ * want to use the 842 hardware compression interface, which is at:
+ * drivers/crypto/nx/nx-842-crypto.c
+ */
+
+#include <crypto/internal/scompress.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/sw842.h>
+
+static void *crypto842_alloc_ctx(void)
+{
+	void *ctx;
+
+	ctx = kmalloc(SW842_MEM_COMPRESS, GFP_KERNEL);
+	if (!ctx)
+		return ERR_PTR(-ENOMEM);
+
+	return ctx;
+}
+
+static void crypto842_free_ctx(void *ctx)
+{
+	kfree(ctx);
+}
+
+static int crypto842_scompress(struct crypto_scomp *tfm,
+			       const u8 *src, unsigned int slen,
+			       u8 *dst, unsigned int *dlen, void *ctx)
+{
+	return sw842_compress(src, slen, dst, dlen, ctx);
+}
+
+static int crypto842_sdecompress(struct crypto_scomp *tfm,
+				 const u8 *src, unsigned int slen,
+				 u8 *dst, unsigned int *dlen, void *ctx)
+{
+	return sw842_decompress(src, slen, dst, dlen);
+}
+
+static struct scomp_alg scomp = {
+	.streams		= {
+		.alloc_ctx	= crypto842_alloc_ctx,
+		.free_ctx	= crypto842_free_ctx,
+	},
+	.compress		= crypto842_scompress,
+	.decompress		= crypto842_sdecompress,
+	.base			= {
+		.cra_name	= "842",
+		.cra_driver_name = "842-scomp",
+		.cra_priority	 = 100,
+		.cra_module	 = THIS_MODULE,
+	}
+};
+
+static int __init crypto842_mod_init(void)
+{
+	return crypto_register_scomp(&scomp);
+}
+module_init(crypto842_mod_init);
+
+static void __exit crypto842_mod_exit(void)
+{
+	crypto_unregister_scomp(&scomp);
+}
+module_exit(crypto842_mod_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("842 Software Compression Algorithm");
+MODULE_ALIAS_CRYPTO("842");
+MODULE_ALIAS_CRYPTO("842-generic");
+MODULE_AUTHOR("Dan Streetman <ddstreet@ieee.org>");