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, 110 insertions, 0 deletions

diff --git a/fs/jffs2/compr_lzo.c b/fs/jffs2/compr_lzo.c
new file mode 100644
index 000000000..c553bd650
--- /dev/null
+++ b/fs/jffs2/compr_lzo.c
@@ -0,0 +1,110 @@
+/*
+ * JFFS2 -- Journalling Flash File System, Version 2.
+ *
+ * Copyright © 2007 Nokia Corporation. All rights reserved.
+ * Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>
+ *
+ * Created by Richard Purdie <rpurdie@openedhand.com>
+ *
+ * For licensing information, see the file 'LICENCE' in this directory.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/vmalloc.h>
+#include <linux/init.h>
+#include <linux/lzo.h>
+#include "compr.h"
+
+static void *lzo_mem;
+static void *lzo_compress_buf;
+static DEFINE_MUTEX(deflate_mutex);	/* for lzo_mem and lzo_compress_buf */
+
+static void free_workspace(void)
+{
+	vfree(lzo_mem);
+	vfree(lzo_compress_buf);
+}
+
+static int __init alloc_workspace(void)
+{
+	lzo_mem = vmalloc(LZO1X_MEM_COMPRESS);
+	lzo_compress_buf = vmalloc(lzo1x_worst_compress(PAGE_SIZE));
+
+	if (!lzo_mem || !lzo_compress_buf) {
+		free_workspace();
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+static int jffs2_lzo_compress(unsigned char *data_in, unsigned char *cpage_out,
+			      uint32_t *sourcelen, uint32_t *dstlen)
+{
+	size_t compress_size;
+	int ret;
+
+	mutex_lock(&deflate_mutex);
+	ret = lzo1x_1_compress(data_in, *sourcelen, lzo_compress_buf, &compress_size, lzo_mem);
+	if (ret != LZO_E_OK)
+		goto fail;
+
+	if (compress_size > *dstlen)
+		goto fail;
+
+	memcpy(cpage_out, lzo_compress_buf, compress_size);
+	mutex_unlock(&deflate_mutex);
+
+	*dstlen = compress_size;
+	return 0;
+
+ fail:
+	mutex_unlock(&deflate_mutex);
+	return -1;
+}
+
+static int jffs2_lzo_decompress(unsigned char *data_in, unsigned char *cpage_out,
+				 uint32_t srclen, uint32_t destlen)
+{
+	size_t dl = destlen;
+	int ret;
+
+	ret = lzo1x_decompress_safe(data_in, srclen, cpage_out, &dl);
+
+	if (ret != LZO_E_OK || dl != destlen)
+		return -1;
+
+	return 0;
+}
+
+static struct jffs2_compressor jffs2_lzo_comp = {
+	.priority = JFFS2_LZO_PRIORITY,
+	.name = "lzo",
+	.compr = JFFS2_COMPR_LZO,
+	.compress = &jffs2_lzo_compress,
+	.decompress = &jffs2_lzo_decompress,
+	.disabled = 0,
+};
+
+int __init jffs2_lzo_init(void)
+{
+	int ret;
+
+	ret = alloc_workspace();
+	if (ret < 0)
+		return ret;
+
+	ret = jffs2_register_compressor(&jffs2_lzo_comp);
+	if (ret)
+		free_workspace();
+
+	return ret;
+}
+
+void jffs2_lzo_exit(void)
+{
+	jffs2_unregister_compressor(&jffs2_lzo_comp);
+	free_workspace();
+}