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, 240 insertions, 0 deletions

diff --git a/drivers/ata/pata_falcon.c b/drivers/ata/pata_falcon.c
new file mode 100644
index 000000000..334c4eea4
--- /dev/null
+++ b/drivers/ata/pata_falcon.c
@@ -0,0 +1,240 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Atari Falcon PATA controller driver
+ *
+ * Copyright (c) 2016 Samsung Electronics Co., Ltd.
+ *		http://www.samsung.com
+ *
+ * Based on falconide.c:
+ *
+ *     Created 12 Jul 1997 by Geert Uytterhoeven
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/blkdev.h>
+#include <linux/delay.h>
+#include <scsi/scsi_host.h>
+#include <scsi/scsi_cmnd.h>
+#include <linux/ata.h>
+#include <linux/libata.h>
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+
+#include <asm/setup.h>
+#include <asm/atarihw.h>
+#include <asm/atariints.h>
+#include <asm/atari_stdma.h>
+
+#define DRV_NAME "pata_falcon"
+#define DRV_VERSION "0.1.0"
+
+static int pata_falcon_swap_mask;
+
+module_param_named(data_swab, pata_falcon_swap_mask, int, 0444);
+MODULE_PARM_DESC(data_swab, "Data byte swap enable/disable bitmap (0x1==drive1, 0x2==drive2, 0x4==drive3, 0x8==drive4, default==0)");
+
+static const struct scsi_host_template pata_falcon_sht = {
+	ATA_PIO_SHT(DRV_NAME),
+};
+
+static unsigned int pata_falcon_data_xfer(struct ata_queued_cmd *qc,
+					  unsigned char *buf,
+					  unsigned int buflen, int rw)
+{
+	struct ata_device *dev = qc->dev;
+	struct ata_port *ap = dev->link->ap;
+	void __iomem *data_addr = ap->ioaddr.data_addr;
+	unsigned int words = buflen >> 1;
+	struct scsi_cmnd *cmd = qc->scsicmd;
+	bool swap = 1;
+
+	if (dev->class == ATA_DEV_ATA && cmd &&
+	    !blk_rq_is_passthrough(scsi_cmd_to_rq(cmd)))
+		swap = (uintptr_t)ap->private_data & BIT(dev->devno);
+
+	/* Transfer multiple of 2 bytes */
+	if (rw == READ) {
+		if (swap)
+			raw_insw_swapw(data_addr, (u16 *)buf, words);
+		else
+			raw_insw(data_addr, (u16 *)buf, words);
+	} else {
+		if (swap)
+			raw_outsw_swapw(data_addr, (u16 *)buf, words);
+		else
+			raw_outsw(data_addr, (u16 *)buf, words);
+	}
+
+	/* Transfer trailing byte, if any. */
+	if (unlikely(buflen & 0x01)) {
+		unsigned char pad[2] = { };
+
+		/* Point buf to the tail of buffer */
+		buf += buflen - 1;
+
+		if (rw == READ) {
+			if (swap)
+				raw_insw_swapw(data_addr, (u16 *)pad, 1);
+			else
+				raw_insw(data_addr, (u16 *)pad, 1);
+			*buf = pad[0];
+		} else {
+			pad[0] = *buf;
+			if (swap)
+				raw_outsw_swapw(data_addr, (u16 *)pad, 1);
+			else
+				raw_outsw(data_addr, (u16 *)pad, 1);
+		}
+		words++;
+	}
+
+	return words << 1;
+}
+
+/*
+ * Provide our own set_mode() as we don't want to change anything that has
+ * already been configured..
+ */
+static int pata_falcon_set_mode(struct ata_link *link,
+				struct ata_device **unused)
+{
+	struct ata_device *dev;
+
+	ata_for_each_dev(dev, link, ENABLED) {
+		/* We don't really care */
+		dev->pio_mode = dev->xfer_mode = XFER_PIO_0;
+		dev->xfer_shift = ATA_SHIFT_PIO;
+		dev->flags |= ATA_DFLAG_PIO;
+		ata_dev_info(dev, "configured for PIO\n");
+	}
+	return 0;
+}
+
+static struct ata_port_operations pata_falcon_ops = {
+	.inherits	= &ata_sff_port_ops,
+	.sff_data_xfer	= pata_falcon_data_xfer,
+	.cable_detect	= ata_cable_unknown,
+	.set_mode	= pata_falcon_set_mode,
+};
+
+static int pata_falcon_init_one(struct platform_device *pdev)
+{
+	struct resource *base_mem_res, *ctl_mem_res;
+	struct resource *base_res, *ctl_res, *irq_res;
+	struct ata_host *host;
+	struct ata_port *ap;
+	void __iomem *base, *ctl_base;
+	int mask_shift = 0; /* Q40 & Falcon default */
+	int irq = 0, io_offset = 1, reg_shift = 2; /* Falcon defaults */
+
+	dev_info(&pdev->dev, "Atari Falcon and Q40/Q60 PATA controller\n");
+
+	base_res = platform_get_resource(pdev, IORESOURCE_IO, 0);
+	if (base_res && !devm_request_region(&pdev->dev, base_res->start,
+					   resource_size(base_res), DRV_NAME)) {
+		dev_err(&pdev->dev, "resources busy\n");
+		return -EBUSY;
+	}
+
+	ctl_res = platform_get_resource(pdev, IORESOURCE_IO, 1);
+	if (ctl_res && !devm_request_region(&pdev->dev, ctl_res->start,
+					    resource_size(ctl_res), DRV_NAME)) {
+		dev_err(&pdev->dev, "resources busy\n");
+		return -EBUSY;
+	}
+
+	base_mem_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!base_mem_res)
+		return -ENODEV;
+	if (!devm_request_mem_region(&pdev->dev, base_mem_res->start,
+				     resource_size(base_mem_res), DRV_NAME)) {
+		dev_err(&pdev->dev, "resources busy\n");
+		return -EBUSY;
+	}
+
+	ctl_mem_res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+	if (!ctl_mem_res)
+		return -ENODEV;
+
+	/* allocate host */
+	host = ata_host_alloc(&pdev->dev, 1);
+	if (!host)
+		return -ENOMEM;
+	ap = host->ports[0];
+
+	ap->ops = &pata_falcon_ops;
+	ap->pio_mask = ATA_PIO4;
+	ap->flags |= ATA_FLAG_SLAVE_POSS | ATA_FLAG_NO_IORDY;
+
+	/* N.B. this assumes data_addr will be used for word-sized I/O only */
+	ap->ioaddr.data_addr = (void __iomem *)base_mem_res->start;
+
+	if (base_res) {		/* only Q40 has IO resources */
+		io_offset = 0x10000;
+		reg_shift = 0;
+		base = (void __iomem *)base_res->start;
+		ctl_base = (void __iomem *)ctl_res->start;
+	} else {
+		base = (void __iomem *)base_mem_res->start;
+		ctl_base = (void __iomem *)ctl_mem_res->start;
+	}
+
+	ap->ioaddr.error_addr	= base + io_offset + (1 << reg_shift);
+	ap->ioaddr.feature_addr	= base + io_offset + (1 << reg_shift);
+	ap->ioaddr.nsect_addr	= base + io_offset + (2 << reg_shift);
+	ap->ioaddr.lbal_addr	= base + io_offset + (3 << reg_shift);
+	ap->ioaddr.lbam_addr	= base + io_offset + (4 << reg_shift);
+	ap->ioaddr.lbah_addr	= base + io_offset + (5 << reg_shift);
+	ap->ioaddr.device_addr	= base + io_offset + (6 << reg_shift);
+	ap->ioaddr.status_addr	= base + io_offset + (7 << reg_shift);
+	ap->ioaddr.command_addr	= base + io_offset + (7 << reg_shift);
+
+	ap->ioaddr.altstatus_addr	= ctl_base + io_offset;
+	ap->ioaddr.ctl_addr		= ctl_base + io_offset;
+
+	ata_port_desc(ap, "cmd %px ctl %px data %px",
+		      base, ctl_base, ap->ioaddr.data_addr);
+
+	if (pdev->id > 0)
+		mask_shift = 2;
+	ap->private_data = (void *)(uintptr_t)(pata_falcon_swap_mask >> mask_shift);
+
+	irq_res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
+	if (irq_res && irq_res->start > 0) {
+		irq = irq_res->start;
+	} else {
+		ap->flags |= ATA_FLAG_PIO_POLLING;
+		ata_port_desc(ap, "no IRQ, using PIO polling");
+	}
+
+	/* activate */
+	return ata_host_activate(host, irq, irq ? ata_sff_interrupt : NULL,
+				 IRQF_SHARED, &pata_falcon_sht);
+}
+
+static void pata_falcon_remove_one(struct platform_device *pdev)
+{
+	struct ata_host *host = platform_get_drvdata(pdev);
+
+	ata_host_detach(host);
+}
+
+static struct platform_driver pata_falcon_driver = {
+	.probe = pata_falcon_init_one,
+	.remove = pata_falcon_remove_one,
+	.driver = {
+		.name	= "atari-falcon-ide",
+	},
+};
+
+module_platform_driver(pata_falcon_driver);
+
+MODULE_AUTHOR("Bartlomiej Zolnierkiewicz");
+MODULE_DESCRIPTION("low-level driver for Atari Falcon PATA");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:atari-falcon-ide");
+MODULE_VERSION(DRV_VERSION);