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, 55 insertions, 0 deletions

diff --git a/drivers/sh/intc/virq-debugfs.c b/drivers/sh/intc/virq-debugfs.c
new file mode 100644
index 000000000..5dd8febe6
--- /dev/null
+++ b/drivers/sh/intc/virq-debugfs.c
@@ -0,0 +1,55 @@
+/*
+ * Support for virtual IRQ subgroups debugfs mapping.
+ *
+ * Copyright (C) 2010  Paul Mundt
+ *
+ * Modelled after arch/powerpc/kernel/irq.c.
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+#include <linux/seq_file.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/irq.h>
+#include <linux/debugfs.h>
+#include "internals.h"
+
+static int intc_irq_xlate_show(struct seq_file *m, void *priv)
+{
+	const unsigned int nr_irqs = irq_get_nr_irqs();
+	int i;
+
+	seq_printf(m, "%-5s  %-7s  %-15s\n", "irq", "enum", "chip name");
+
+	for (i = 1; i < nr_irqs; i++) {
+		struct intc_map_entry *entry = intc_irq_xlate_get(i);
+		struct intc_desc_int *desc = entry->desc;
+
+		if (!desc)
+			continue;
+
+		seq_printf(m, "%5d  ", i);
+		seq_printf(m, "0x%05x  ", entry->enum_id);
+		seq_printf(m, "%-15s\n", desc->chip.name);
+	}
+
+	return 0;
+}
+
+DEFINE_SHOW_ATTRIBUTE(intc_irq_xlate);
+
+static int __init intc_irq_xlate_init(void)
+{
+	/*
+	 * XXX.. use arch_debugfs_dir here when all of the intc users are
+	 * converted.
+	 */
+	if (debugfs_create_file("intc_irq_xlate", S_IRUGO, NULL, NULL,
+				&intc_irq_xlate_fops) == NULL)
+		return -ENOMEM;
+
+	return 0;
+}
+fs_initcall(intc_irq_xlate_init);