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, 213 insertions, 0 deletions

diff --git a/drivers/scsi/arm/oak.c b/drivers/scsi/arm/oak.c
new file mode 100644
index 000000000..d69245007
--- /dev/null
+++ b/drivers/scsi/arm/oak.c
@@ -0,0 +1,213 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Oak Generic NCR5380 driver
+ *
+ * Copyright 1995-2002, Russell King
+ */
+
+#include <linux/module.h>
+#include <linux/ioport.h>
+#include <linux/blkdev.h>
+#include <linux/init.h>
+
+#include <asm/ecard.h>
+#include <asm/io.h>
+
+#include <scsi/scsi_host.h>
+
+#define priv(host)			((struct NCR5380_hostdata *)(host)->hostdata)
+
+#define NCR5380_read(reg)           readb(hostdata->io + ((reg) << 2))
+#define NCR5380_write(reg, value)   writeb(value, hostdata->io + ((reg) << 2))
+
+#define NCR5380_dma_xfer_len		NCR5380_dma_xfer_none
+#define NCR5380_dma_recv_setup		oakscsi_pread
+#define NCR5380_dma_send_setup		oakscsi_pwrite
+#define NCR5380_dma_residual		NCR5380_dma_residual_none
+
+#define NCR5380_queue_command		oakscsi_queue_command
+#define NCR5380_info			oakscsi_info
+
+#define NCR5380_implementation_fields	/* none */
+
+#include "../NCR5380.h"
+
+#undef START_DMA_INITIATOR_RECEIVE_REG
+#define START_DMA_INITIATOR_RECEIVE_REG	(128 + 7)
+
+#define STAT	((128 + 16) << 2)
+#define DATA	((128 + 8) << 2)
+
+static inline int oakscsi_pwrite(struct NCR5380_hostdata *hostdata,
+                                 unsigned char *addr, int len)
+{
+  u8 __iomem *base = hostdata->io;
+
+printk("writing %p len %d\n",addr, len);
+
+  while(1)
+  {
+    int status;
+    while (((status = readw(base + STAT)) & 0x100)==0);
+  }
+  return 0;
+}
+
+static inline int oakscsi_pread(struct NCR5380_hostdata *hostdata,
+                                unsigned char *addr, int len)
+{
+  u8 __iomem *base = hostdata->io;
+
+printk("reading %p len %d\n", addr, len);
+  while(len > 0)
+  {
+    unsigned int status, timeout;
+    unsigned long b;
+    
+    timeout = 0x01FFFFFF;
+    
+    while (((status = readw(base + STAT)) & 0x100)==0)
+    {
+      timeout--;
+      if(status & 0x200 || !timeout)
+      {
+        printk("status = %08X\n", status);
+        return -1;
+      }
+    }
+
+    if(len >= 128)
+    {
+      readsw(base + DATA, addr, 128);
+      addr += 128;
+      len -= 128;
+    }
+    else
+    {
+      b = (unsigned long) readw(base + DATA);
+      *addr ++ = b;
+      len -= 1;
+      if(len)
+        *addr ++ = b>>8;
+      len -= 1;
+    }
+  }
+  return 0;
+}
+
+#undef STAT
+#undef DATA
+
+#include "../NCR5380.c"
+
+static const struct scsi_host_template oakscsi_template = {
+	.module			= THIS_MODULE,
+	.name			= "Oak 16-bit SCSI",
+	.info			= oakscsi_info,
+	.queuecommand		= oakscsi_queue_command,
+	.eh_abort_handler	= NCR5380_abort,
+	.eh_host_reset_handler	= NCR5380_host_reset,
+	.can_queue		= 16,
+	.this_id		= 7,
+	.sg_tablesize		= SG_ALL,
+	.cmd_per_lun		= 2,
+	.dma_boundary		= PAGE_SIZE - 1,
+	.proc_name		= "oakscsi",
+	.cmd_size		= sizeof(struct NCR5380_cmd),
+	.max_sectors		= 128,
+};
+
+static int oakscsi_probe(struct expansion_card *ec, const struct ecard_id *id)
+{
+	struct Scsi_Host *host;
+	int ret;
+
+	ret = ecard_request_resources(ec);
+	if (ret)
+		goto out;
+
+	host = scsi_host_alloc(&oakscsi_template, sizeof(struct NCR5380_hostdata));
+	if (!host) {
+		ret = -ENOMEM;
+		goto release;
+	}
+
+	priv(host)->io = ioremap(ecard_resource_start(ec, ECARD_RES_MEMC),
+	                         ecard_resource_len(ec, ECARD_RES_MEMC));
+	if (!priv(host)->io) {
+		ret = -ENOMEM;
+		goto unreg;
+	}
+
+	host->irq = NO_IRQ;
+
+	ret = NCR5380_init(host, FLAG_DMA_FIXUP | FLAG_LATE_DMA_SETUP);
+	if (ret)
+		goto out_unmap;
+
+	NCR5380_maybe_reset_bus(host);
+
+	ret = scsi_add_host(host, &ec->dev);
+	if (ret)
+		goto out_exit;
+
+	scsi_scan_host(host);
+	goto out;
+
+ out_exit:
+	NCR5380_exit(host);
+ out_unmap:
+	iounmap(priv(host)->io);
+ unreg:
+	scsi_host_put(host);
+ release:
+	ecard_release_resources(ec);
+ out:
+	return ret;
+}
+
+static void oakscsi_remove(struct expansion_card *ec)
+{
+	struct Scsi_Host *host = ecard_get_drvdata(ec);
+	void __iomem *base = priv(host)->io;
+
+	ecard_set_drvdata(ec, NULL);
+	scsi_remove_host(host);
+
+	NCR5380_exit(host);
+	scsi_host_put(host);
+	iounmap(base);
+	ecard_release_resources(ec);
+}
+
+static const struct ecard_id oakscsi_cids[] = {
+	{ MANU_OAK, PROD_OAK_SCSI },
+	{ 0xffff, 0xffff }
+};
+
+static struct ecard_driver oakscsi_driver = {
+	.probe		= oakscsi_probe,
+	.remove		= oakscsi_remove,
+	.id_table	= oakscsi_cids,
+	.drv = {
+		.name		= "oakscsi",
+	},
+};
+
+static int __init oakscsi_init(void)
+{
+	return ecard_register_driver(&oakscsi_driver);
+}
+
+static void __exit oakscsi_exit(void)
+{
+	ecard_remove_driver(&oakscsi_driver);
+}
+
+module_init(oakscsi_init);
+module_exit(oakscsi_exit);
+
+MODULE_AUTHOR("Russell King");
+MODULE_DESCRIPTION("Oak SCSI driver");
+MODULE_LICENSE("GPL");
+