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, 73 insertions, 0 deletions

diff --git a/drivers/scsi/a3000.h b/drivers/scsi/a3000.h
new file mode 100644
index 000000000..5cb3e7535
--- /dev/null
+++ b/drivers/scsi/a3000.h
@@ -0,0 +1,73 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef A3000_H
+#define A3000_H
+
+/* $Id: a3000.h,v 1.4 1997/01/19 23:07:10 davem Exp $
+ *
+ * Header file for the Amiga 3000 built-in SCSI controller for Linux
+ *
+ * Written and (C) 1993, Hamish Macdonald, see a3000.c for more info
+ *
+ */
+
+#include <linux/types.h>
+
+#ifndef CMD_PER_LUN
+#define CMD_PER_LUN		2
+#endif
+
+#ifndef CAN_QUEUE
+#define CAN_QUEUE		16
+#endif
+
+/*
+ * if the transfer address ANDed with this results in a non-zero
+ * result, then we can't use DMA.
+ */
+#define A3000_XFER_MASK		(0x00000003)
+
+struct a3000_scsiregs {
+		 unsigned char	pad1[2];
+	volatile unsigned short	DAWR;
+	volatile unsigned int	WTC;
+		 unsigned char	pad2[2];
+	volatile unsigned short	CNTR;
+	volatile unsigned long	ACR;
+		 unsigned char	pad3[2];
+	volatile unsigned short	ST_DMA;
+		 unsigned char	pad4[2];
+	volatile unsigned short	FLUSH;
+		 unsigned char	pad5[2];
+	volatile unsigned short	CINT;
+		 unsigned char	pad6[2];
+	volatile unsigned short	ISTR;
+		 unsigned char	pad7[30];
+	volatile unsigned short	SP_DMA;
+		 unsigned char	pad8;
+	volatile unsigned char	SASR;
+		 unsigned char	pad9;
+	volatile unsigned char	SCMD;
+};
+
+#define DAWR_A3000		(3)
+
+/* CNTR bits. */
+#define CNTR_TCEN		(1<<5)
+#define CNTR_PREST		(1<<4)
+#define CNTR_PDMD		(1<<3)
+#define CNTR_INTEN		(1<<2)
+#define CNTR_DDIR		(1<<1)
+#define CNTR_IO_DX		(1<<0)
+
+/* ISTR bits. */
+#define ISTR_INTX		(1<<8)
+#define ISTR_INT_F		(1<<7)
+#define ISTR_INTS		(1<<6)
+#define ISTR_E_INT		(1<<5)
+#define ISTR_INT_P		(1<<4)
+#define ISTR_UE_INT		(1<<3)
+#define ISTR_OE_INT		(1<<2)
+#define ISTR_FF_FLG		(1<<1)
+#define ISTR_FE_FLG		(1<<0)
+
+#endif /* A3000_H */