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, 109 insertions, 0 deletions

diff --git a/drivers/ata/pata_netcell.c b/drivers/ata/pata_netcell.c
new file mode 100644
index 000000000..c0b2897fc
--- /dev/null
+++ b/drivers/ata/pata_netcell.c
@@ -0,0 +1,109 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *    pata_netcell.c - Netcell PATA driver
+ *
+ *	(c) 2006 Red Hat
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/blkdev.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <scsi/scsi_host.h>
+#include <linux/libata.h>
+#include <linux/ata.h>
+
+#define DRV_NAME	"pata_netcell"
+#define DRV_VERSION	"0.1.7"
+
+/* No PIO or DMA methods needed for this device */
+
+static unsigned int netcell_read_id(struct ata_device *adev,
+				    struct ata_taskfile *tf, __le16 *id)
+{
+	unsigned int err_mask = ata_do_dev_read_id(adev, tf, id);
+
+	/* Firmware forgets to mark words 85-87 valid */
+	if (err_mask == 0)
+		id[ATA_ID_CSF_DEFAULT] |= cpu_to_le16(0x4000);
+	return err_mask;
+}
+
+static const struct scsi_host_template netcell_sht = {
+	ATA_BMDMA_SHT(DRV_NAME),
+};
+
+static struct ata_port_operations netcell_ops = {
+	.inherits	= &ata_bmdma_port_ops,
+	.cable_detect	= ata_cable_80wire,
+	.read_id	= netcell_read_id,
+};
+
+
+/**
+ *	netcell_init_one - Register Netcell ATA PCI device with kernel services
+ *	@pdev: PCI device to register
+ *	@ent: Entry in netcell_pci_tbl matching with @pdev
+ *
+ *	Called from kernel PCI layer.
+ *
+ *	LOCKING:
+ *	Inherited from PCI layer (may sleep).
+ *
+ *	RETURNS:
+ *	Zero on success, or -ERRNO value.
+ */
+
+static int netcell_init_one (struct pci_dev *pdev, const struct pci_device_id *ent)
+{
+	static const struct ata_port_info info = {
+		.flags		= ATA_FLAG_SLAVE_POSS,
+		/* Actually we don't really care about these as the
+		   firmware deals with it */
+		.pio_mask	= ATA_PIO4,
+		.mwdma_mask	= ATA_MWDMA2,
+		.udma_mask 	= ATA_UDMA5, /* UDMA 133 */
+		.port_ops	= &netcell_ops,
+	};
+	const struct ata_port_info *port_info[] = { &info, NULL };
+	int rc;
+
+	ata_print_version_once(&pdev->dev, DRV_VERSION);
+
+	rc = pcim_enable_device(pdev);
+	if (rc)
+		return rc;
+
+	/* Any chip specific setup/optimisation/messages here */
+	ata_pci_bmdma_clear_simplex(pdev);
+
+	/* And let the library code do the work */
+	return ata_pci_bmdma_init_one(pdev, port_info, &netcell_sht, NULL, 0);
+}
+
+static const struct pci_device_id netcell_pci_tbl[] = {
+	{ PCI_VDEVICE(NETCELL, PCI_DEVICE_ID_REVOLUTION), },
+
+	{ }	/* terminate list */
+};
+
+static struct pci_driver netcell_pci_driver = {
+	.name			= DRV_NAME,
+	.id_table		= netcell_pci_tbl,
+	.probe			= netcell_init_one,
+	.remove			= ata_pci_remove_one,
+#ifdef CONFIG_PM_SLEEP
+	.suspend		= ata_pci_device_suspend,
+	.resume			= ata_pci_device_resume,
+#endif
+};
+
+module_pci_driver(netcell_pci_driver);
+
+MODULE_AUTHOR("Alan Cox");
+MODULE_DESCRIPTION("SCSI low-level driver for Netcell PATA RAID");
+MODULE_LICENSE("GPL");
+MODULE_DEVICE_TABLE(pci, netcell_pci_tbl);
+MODULE_VERSION(DRV_VERSION);