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, 304 insertions, 0 deletions

diff --git a/drivers/scsi/a2091.c b/drivers/scsi/a2091.c
new file mode 100644
index 000000000..f81e53b53
--- /dev/null
+++ b/drivers/scsi/a2091.c
@@ -0,0 +1,304 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/types.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/zorro.h>
+#include <linux/module.h>
+
+#include <asm/page.h>
+#include <asm/amigaints.h>
+#include <asm/amigahw.h>
+
+#include <scsi/scsi.h>
+#include <scsi/scsi_cmnd.h>
+#include <scsi/scsi_device.h>
+#include <scsi/scsi_eh.h>
+#include <scsi/scsi_tcq.h>
+#include "wd33c93.h"
+#include "a2091.h"
+
+
+struct a2091_hostdata {
+	struct WD33C93_hostdata wh;
+	struct a2091_scsiregs *regs;
+	struct device *dev;
+};
+
+#define DMA_DIR(d)   ((d == DATA_OUT_DIR) ? DMA_TO_DEVICE : DMA_FROM_DEVICE)
+
+static irqreturn_t a2091_intr(int irq, void *data)
+{
+	struct Scsi_Host *instance = data;
+	struct a2091_hostdata *hdata = shost_priv(instance);
+	unsigned int status = hdata->regs->ISTR;
+	unsigned long flags;
+
+	if (!(status & (ISTR_INT_F | ISTR_INT_P)) || !(status & ISTR_INTS))
+		return IRQ_NONE;
+
+	spin_lock_irqsave(instance->host_lock, flags);
+	wd33c93_intr(instance);
+	spin_unlock_irqrestore(instance->host_lock, flags);
+	return IRQ_HANDLED;
+}
+
+static int dma_setup(struct scsi_cmnd *cmd, int dir_in)
+{
+	struct scsi_pointer *scsi_pointer = WD33C93_scsi_pointer(cmd);
+	unsigned long len = scsi_pointer->this_residual;
+	struct Scsi_Host *instance = cmd->device->host;
+	struct a2091_hostdata *hdata = shost_priv(instance);
+	struct WD33C93_hostdata *wh = &hdata->wh;
+	struct a2091_scsiregs *regs = hdata->regs;
+	unsigned short cntr = CNTR_PDMD | CNTR_INTEN;
+	dma_addr_t addr;
+
+	addr = dma_map_single(hdata->dev, scsi_pointer->ptr,
+			      len, DMA_DIR(dir_in));
+	if (dma_mapping_error(hdata->dev, addr)) {
+		dev_warn(hdata->dev, "cannot map SCSI data block %p\n",
+			 scsi_pointer->ptr);
+		return 1;
+	}
+	scsi_pointer->dma_handle = addr;
+
+	/* don't allow DMA if the physical address is bad */
+	if (addr & A2091_XFER_MASK) {
+		/* drop useless mapping */
+		dma_unmap_single(hdata->dev, scsi_pointer->dma_handle,
+				 scsi_pointer->this_residual,
+				 DMA_DIR(dir_in));
+		scsi_pointer->dma_handle = (dma_addr_t) NULL;
+
+		wh->dma_bounce_len = (scsi_pointer->this_residual + 511) & ~0x1ff;
+		wh->dma_bounce_buffer = kmalloc(wh->dma_bounce_len,
+						GFP_KERNEL);
+
+		/* can't allocate memory; use PIO */
+		if (!wh->dma_bounce_buffer) {
+			wh->dma_bounce_len = 0;
+			return 1;
+		}
+
+		if (!dir_in) {
+			/* copy to bounce buffer for a write */
+			memcpy(wh->dma_bounce_buffer, scsi_pointer->ptr,
+			       scsi_pointer->this_residual);
+		}
+
+		/* will flush/invalidate cache for us */
+		addr = dma_map_single(hdata->dev, wh->dma_bounce_buffer,
+				      wh->dma_bounce_len, DMA_DIR(dir_in));
+		/* can't map buffer; use PIO */
+		if (dma_mapping_error(hdata->dev, addr)) {
+			dev_warn(hdata->dev, "cannot map bounce buffer %p\n",
+				 wh->dma_bounce_buffer);
+			return 1;
+		}
+
+		/* the bounce buffer may not be in the first 16M of physmem */
+		if (addr & A2091_XFER_MASK) {
+			/* we could use chipmem... maybe later */
+			kfree(wh->dma_bounce_buffer);
+			wh->dma_bounce_buffer = NULL;
+			wh->dma_bounce_len = 0;
+			return 1;
+		}
+
+		scsi_pointer->dma_handle = addr;
+	}
+
+	/* setup dma direction */
+	if (!dir_in)
+		cntr |= CNTR_DDIR;
+
+	/* remember direction */
+	wh->dma_dir = dir_in;
+
+	regs->CNTR = cntr;
+
+	/* setup DMA *physical* address */
+	regs->ACR = addr;
+
+	/* no more cache flush here - dma_map_single() takes care */
+
+	/* start DMA */
+	regs->ST_DMA = 1;
+
+	/* return success */
+	return 0;
+}
+
+static void dma_stop(struct Scsi_Host *instance, struct scsi_cmnd *SCpnt,
+		     int status)
+{
+	struct scsi_pointer *scsi_pointer = WD33C93_scsi_pointer(SCpnt);
+	struct a2091_hostdata *hdata = shost_priv(instance);
+	struct WD33C93_hostdata *wh = &hdata->wh;
+	struct a2091_scsiregs *regs = hdata->regs;
+
+	/* disable SCSI interrupts */
+	unsigned short cntr = CNTR_PDMD;
+
+	if (!wh->dma_dir)
+		cntr |= CNTR_DDIR;
+
+	/* disable SCSI interrupts */
+	regs->CNTR = cntr;
+
+	/* flush if we were reading */
+	if (wh->dma_dir) {
+		regs->FLUSH = 1;
+		while (!(regs->ISTR & ISTR_FE_FLG))
+			;
+	}
+
+	/* clear a possible interrupt */
+	regs->CINT = 1;
+
+	/* stop DMA */
+	regs->SP_DMA = 1;
+
+	/* restore the CONTROL bits (minus the direction flag) */
+	regs->CNTR = CNTR_PDMD | CNTR_INTEN;
+
+	dma_unmap_single(hdata->dev, scsi_pointer->dma_handle,
+			 scsi_pointer->this_residual,
+			 DMA_DIR(wh->dma_dir));
+
+	/* copy from a bounce buffer, if necessary */
+	if (status && wh->dma_bounce_buffer) {
+		if (wh->dma_dir)
+			memcpy(scsi_pointer->ptr, wh->dma_bounce_buffer,
+			       scsi_pointer->this_residual);
+		kfree(wh->dma_bounce_buffer);
+		wh->dma_bounce_buffer = NULL;
+		wh->dma_bounce_len = 0;
+	}
+}
+
+static const struct scsi_host_template a2091_scsi_template = {
+	.module			= THIS_MODULE,
+	.name			= "Commodore A2091/A590 SCSI",
+	.show_info		= wd33c93_show_info,
+	.write_info		= wd33c93_write_info,
+	.proc_name		= "A2901",
+	.queuecommand		= wd33c93_queuecommand,
+	.eh_abort_handler	= wd33c93_abort,
+	.eh_host_reset_handler	= wd33c93_host_reset,
+	.can_queue		= CAN_QUEUE,
+	.this_id		= 7,
+	.sg_tablesize		= SG_ALL,
+	.cmd_per_lun		= CMD_PER_LUN,
+	.dma_boundary		= PAGE_SIZE - 1,
+	.cmd_size		= sizeof(struct scsi_pointer),
+};
+
+static int a2091_probe(struct zorro_dev *z, const struct zorro_device_id *ent)
+{
+	struct Scsi_Host *instance;
+	int error;
+	struct a2091_scsiregs *regs;
+	wd33c93_regs wdregs;
+	struct a2091_hostdata *hdata;
+
+	if (dma_set_mask_and_coherent(&z->dev, DMA_BIT_MASK(24))) {
+		dev_warn(&z->dev, "cannot use 24 bit DMA\n");
+		return -ENODEV;
+	}
+
+	if (!request_mem_region(z->resource.start, 256, "wd33c93"))
+		return -EBUSY;
+
+	instance = scsi_host_alloc(&a2091_scsi_template,
+				   sizeof(struct a2091_hostdata));
+	if (!instance) {
+		error = -ENOMEM;
+		goto fail_alloc;
+	}
+
+	instance->irq = IRQ_AMIGA_PORTS;
+	instance->unique_id = z->slotaddr;
+
+	regs = ZTWO_VADDR(z->resource.start);
+	regs->DAWR = DAWR_A2091;
+
+	wdregs.SASR = &regs->SASR;
+	wdregs.SCMD = &regs->SCMD;
+
+	hdata = shost_priv(instance);
+	hdata->dev = &z->dev;
+	hdata->wh.no_sync = 0xff;
+	hdata->wh.fast = 0;
+	hdata->wh.dma_mode = CTRL_DMA;
+	hdata->regs = regs;
+
+	wd33c93_init(instance, wdregs, dma_setup, dma_stop, WD33C93_FS_8_10);
+	error = request_irq(IRQ_AMIGA_PORTS, a2091_intr, IRQF_SHARED,
+			    "A2091 SCSI", instance);
+	if (error)
+		goto fail_irq;
+
+	regs->CNTR = CNTR_PDMD | CNTR_INTEN;
+
+	error = scsi_add_host(instance, NULL);
+	if (error)
+		goto fail_host;
+
+	zorro_set_drvdata(z, instance);
+
+	scsi_scan_host(instance);
+	return 0;
+
+fail_host:
+	free_irq(IRQ_AMIGA_PORTS, instance);
+fail_irq:
+	scsi_host_put(instance);
+fail_alloc:
+	release_mem_region(z->resource.start, 256);
+	return error;
+}
+
+static void a2091_remove(struct zorro_dev *z)
+{
+	struct Scsi_Host *instance = zorro_get_drvdata(z);
+	struct a2091_hostdata *hdata = shost_priv(instance);
+
+	hdata->regs->CNTR = 0;
+	scsi_remove_host(instance);
+	free_irq(IRQ_AMIGA_PORTS, instance);
+	scsi_host_put(instance);
+	release_mem_region(z->resource.start, 256);
+}
+
+static struct zorro_device_id a2091_zorro_tbl[] = {
+	{ .id = ZORRO_PROD_CBM_A590_A2091_1 },
+	{ .id = ZORRO_PROD_CBM_A590_A2091_2 },
+	{ }
+};
+MODULE_DEVICE_TABLE(zorro, a2091_zorro_tbl);
+
+static struct zorro_driver a2091_driver = {
+	.name		= "a2091",
+	.id_table	= a2091_zorro_tbl,
+	.probe		= a2091_probe,
+	.remove		= a2091_remove,
+};
+
+static int __init a2091_init(void)
+{
+	return zorro_register_driver(&a2091_driver);
+}
+module_init(a2091_init);
+
+static void __exit a2091_exit(void)
+{
+	zorro_unregister_driver(&a2091_driver);
+}
+module_exit(a2091_exit);
+
+MODULE_DESCRIPTION("Commodore A2091/A590 SCSI");
+MODULE_LICENSE("GPL");