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, 296 insertions, 0 deletions

diff --git a/drivers/ata/pata_pxa.c b/drivers/ata/pata_pxa.c
new file mode 100644
index 000000000..a694f6a17
--- /dev/null
+++ b/drivers/ata/pata_pxa.c
@@ -0,0 +1,296 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Generic PXA PATA driver
+ *
+ * Copyright (C) 2010 Marek Vasut <marek.vasut@gmail.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/blkdev.h>
+#include <linux/ata.h>
+#include <linux/libata.h>
+#include <linux/platform_device.h>
+#include <linux/dmaengine.h>
+#include <linux/slab.h>
+#include <linux/completion.h>
+
+#include <scsi/scsi_host.h>
+
+#include <linux/platform_data/ata-pxa.h>
+
+#define DRV_NAME	"pata_pxa"
+#define DRV_VERSION	"0.1"
+
+struct pata_pxa_data {
+	struct dma_chan		*dma_chan;
+	dma_cookie_t		dma_cookie;
+	struct completion	dma_done;
+};
+
+/*
+ * DMA interrupt handler.
+ */
+static void pxa_ata_dma_irq(void *d)
+{
+	struct pata_pxa_data *pd = d;
+	enum dma_status status;
+
+	status = dmaengine_tx_status(pd->dma_chan, pd->dma_cookie, NULL);
+	if (status == DMA_ERROR || status == DMA_COMPLETE)
+		complete(&pd->dma_done);
+}
+
+/*
+ * Prepare taskfile for submission.
+ */
+static enum ata_completion_errors pxa_qc_prep(struct ata_queued_cmd *qc)
+{
+	struct pata_pxa_data *pd = qc->ap->private_data;
+	struct dma_async_tx_descriptor *tx;
+	enum dma_transfer_direction dir;
+
+	if (!(qc->flags & ATA_QCFLAG_DMAMAP))
+		return AC_ERR_OK;
+
+	dir = (qc->dma_dir == DMA_TO_DEVICE ? DMA_MEM_TO_DEV : DMA_DEV_TO_MEM);
+	tx = dmaengine_prep_slave_sg(pd->dma_chan, qc->sg, qc->n_elem, dir,
+				     DMA_PREP_INTERRUPT);
+	if (!tx) {
+		ata_dev_err(qc->dev, "prep_slave_sg() failed\n");
+		return AC_ERR_OK;
+	}
+	tx->callback = pxa_ata_dma_irq;
+	tx->callback_param = pd;
+	pd->dma_cookie = dmaengine_submit(tx);
+
+	return AC_ERR_OK;
+}
+
+/*
+ * Configure the DMA controller, load the DMA descriptors, but don't start the
+ * DMA controller yet. Only issue the ATA command.
+ */
+static void pxa_bmdma_setup(struct ata_queued_cmd *qc)
+{
+	qc->ap->ops->sff_exec_command(qc->ap, &qc->tf);
+}
+
+/*
+ * Execute the DMA transfer.
+ */
+static void pxa_bmdma_start(struct ata_queued_cmd *qc)
+{
+	struct pata_pxa_data *pd = qc->ap->private_data;
+	init_completion(&pd->dma_done);
+	dma_async_issue_pending(pd->dma_chan);
+}
+
+/*
+ * Wait until the DMA transfer completes, then stop the DMA controller.
+ */
+static void pxa_bmdma_stop(struct ata_queued_cmd *qc)
+{
+	struct pata_pxa_data *pd = qc->ap->private_data;
+	enum dma_status status;
+
+	status = dmaengine_tx_status(pd->dma_chan, pd->dma_cookie, NULL);
+	if (status != DMA_ERROR && status != DMA_COMPLETE &&
+	    wait_for_completion_timeout(&pd->dma_done, HZ))
+		ata_dev_err(qc->dev, "Timeout waiting for DMA completion!");
+
+	dmaengine_terminate_all(pd->dma_chan);
+}
+
+/*
+ * Read DMA status. The bmdma_stop() will take care of properly finishing the
+ * DMA transfer so we always have DMA-complete interrupt here.
+ */
+static unsigned char pxa_bmdma_status(struct ata_port *ap)
+{
+	struct pata_pxa_data *pd = ap->private_data;
+	unsigned char ret = ATA_DMA_INTR;
+	struct dma_tx_state state;
+	enum dma_status status;
+
+	status = dmaengine_tx_status(pd->dma_chan, pd->dma_cookie, &state);
+	if (status != DMA_COMPLETE)
+		ret |= ATA_DMA_ERR;
+
+	return ret;
+}
+
+/*
+ * No IRQ register present so we do nothing.
+ */
+static void pxa_irq_clear(struct ata_port *ap)
+{
+}
+
+/*
+ * Check for ATAPI DMA. ATAPI DMA is unsupported by this driver. It's still
+ * unclear why ATAPI has DMA issues.
+ */
+static int pxa_check_atapi_dma(struct ata_queued_cmd *qc)
+{
+	return -EOPNOTSUPP;
+}
+
+static const struct scsi_host_template pxa_ata_sht = {
+	ATA_BMDMA_SHT(DRV_NAME),
+};
+
+static struct ata_port_operations pxa_ata_port_ops = {
+	.inherits		= &ata_bmdma_port_ops,
+	.cable_detect		= ata_cable_40wire,
+
+	.bmdma_setup		= pxa_bmdma_setup,
+	.bmdma_start		= pxa_bmdma_start,
+	.bmdma_stop		= pxa_bmdma_stop,
+	.bmdma_status		= pxa_bmdma_status,
+
+	.check_atapi_dma	= pxa_check_atapi_dma,
+
+	.sff_irq_clear		= pxa_irq_clear,
+
+	.qc_prep		= pxa_qc_prep,
+};
+
+static int pxa_ata_probe(struct platform_device *pdev)
+{
+	struct ata_host *host;
+	struct ata_port *ap;
+	struct pata_pxa_data *data;
+	struct resource *dma_res;
+	struct pata_pxa_pdata *pdata = dev_get_platdata(&pdev->dev);
+	struct dma_slave_config	config;
+	int ret = 0;
+	int irq;
+
+	/*
+	 * Resource validation, three resources are needed:
+	 *  - CMD port base address
+	 *  - CTL port base address
+	 *  - DMA port base address
+	 *  - IRQ pin
+	 */
+	if (pdev->num_resources != 4) {
+		dev_err(&pdev->dev, "invalid number of resources\n");
+		return -EINVAL;
+	}
+
+	/*
+	 * DMA port base address
+	 */
+	dma_res = platform_get_resource(pdev, IORESOURCE_DMA, 0);
+	if (unlikely(dma_res == NULL))
+		return -EINVAL;
+
+	/*
+	 * IRQ pin
+	 */
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	/*
+	 * Allocate the host
+	 */
+	host = ata_host_alloc(&pdev->dev, 1);
+	if (!host)
+		return -ENOMEM;
+
+	ap		= host->ports[0];
+	ap->ops		= &pxa_ata_port_ops;
+	ap->pio_mask	= ATA_PIO4;
+	ap->mwdma_mask	= ATA_MWDMA2;
+
+	ap->ioaddr.cmd_addr	= devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(ap->ioaddr.cmd_addr))
+		return PTR_ERR(ap->ioaddr.cmd_addr);
+	ap->ioaddr.ctl_addr	= devm_platform_ioremap_resource(pdev, 1);
+	if (IS_ERR(ap->ioaddr.ctl_addr))
+		return PTR_ERR(ap->ioaddr.ctl_addr);
+	ap->ioaddr.bmdma_addr	= devm_ioremap(&pdev->dev, dma_res->start,
+						resource_size(dma_res));
+	if (!ap->ioaddr.bmdma_addr)
+		return -ENOMEM;
+
+	/*
+	 * Adjust register offsets
+	 */
+	ap->ioaddr.altstatus_addr = ap->ioaddr.ctl_addr;
+	ap->ioaddr.data_addr	= ap->ioaddr.cmd_addr +
+					(ATA_REG_DATA << pdata->reg_shift);
+	ap->ioaddr.error_addr	= ap->ioaddr.cmd_addr +
+					(ATA_REG_ERR << pdata->reg_shift);
+	ap->ioaddr.feature_addr	= ap->ioaddr.cmd_addr +
+					(ATA_REG_FEATURE << pdata->reg_shift);
+	ap->ioaddr.nsect_addr	= ap->ioaddr.cmd_addr +
+					(ATA_REG_NSECT << pdata->reg_shift);
+	ap->ioaddr.lbal_addr	= ap->ioaddr.cmd_addr +
+					(ATA_REG_LBAL << pdata->reg_shift);
+	ap->ioaddr.lbam_addr	= ap->ioaddr.cmd_addr +
+					(ATA_REG_LBAM << pdata->reg_shift);
+	ap->ioaddr.lbah_addr	= ap->ioaddr.cmd_addr +
+					(ATA_REG_LBAH << pdata->reg_shift);
+	ap->ioaddr.device_addr	= ap->ioaddr.cmd_addr +
+					(ATA_REG_DEVICE << pdata->reg_shift);
+	ap->ioaddr.status_addr	= ap->ioaddr.cmd_addr +
+					(ATA_REG_STATUS << pdata->reg_shift);
+	ap->ioaddr.command_addr	= ap->ioaddr.cmd_addr +
+					(ATA_REG_CMD << pdata->reg_shift);
+
+	/*
+	 * Allocate and load driver's internal data structure
+	 */
+	data = devm_kzalloc(&pdev->dev, sizeof(struct pata_pxa_data),
+								GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	ap->private_data = data;
+
+	memset(&config, 0, sizeof(config));
+	config.src_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
+	config.dst_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
+	config.src_addr = dma_res->start;
+	config.dst_addr = dma_res->start;
+	config.src_maxburst = 32;
+	config.dst_maxburst = 32;
+
+	/*
+	 * Request the DMA channel
+	 */
+	data->dma_chan = devm_dma_request_chan(&pdev->dev, "data");
+	if (IS_ERR(data->dma_chan))
+		return PTR_ERR(data->dma_chan);
+
+	ret = dmaengine_slave_config(data->dma_chan, &config);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "dma configuration failed: %d\n", ret);
+		return ret;
+	}
+
+	/*
+	 * Activate the ATA host
+	 */
+	return ata_host_activate(host, irq, ata_sff_interrupt,
+				pdata->irq_flags, &pxa_ata_sht);
+}
+
+static struct platform_driver pxa_ata_driver = {
+	.probe		= pxa_ata_probe,
+	.remove		= ata_platform_remove_one,
+	.driver		= {
+		.name		= DRV_NAME,
+	},
+};
+
+module_platform_driver(pxa_ata_driver);
+
+MODULE_AUTHOR("Marek Vasut <marek.vasut@gmail.com>");
+MODULE_DESCRIPTION("DMA-capable driver for PATA on PXA CPU");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(DRV_VERSION);
+MODULE_ALIAS("platform:" DRV_NAME);