[PATCH 09/58] mtd: rawnand: gpio: retain open-handle state on removal

[James Hilliard]

A retained MTD handle can outlive GPIO NAND unbind. Drain and disconnect
NAND operations before disabling the chip, and keep the chip metadata
and controller lock alive until the final MTD reference is released.
GPIO and MMIO resources are still released during unbind.

Also release scanned NAND metadata when MTD registration fails, using
retained ownership once a device could have been published.

Fixes: aaf7ea200004 ("[MTD] [NAND] GPIO NAND flash driver")
Signed-off-by: James Hilliard <james.hilliard1 at gmail.com>
---
 drivers/mtd/nand/raw/gpio.c | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/drivers/mtd/nand/raw/gpio.c b/drivers/mtd/nand/raw/gpio.c
index 69e5e43532a4..b6c98c374e39 100644
--- a/drivers/mtd/nand/raw/gpio.c
+++ b/drivers/mtd/nand/raw/gpio.c
@@ -265,6 +265,11 @@ gpio_nand_get_io_sync(struct platform_device *pdev)
 	return platform_get_resource(pdev, IORESOURCE_MEM, 1);
 }
 
+static void gpio_nand_release(struct nand_controller *controller)
+{
+	kfree(container_of(controller, struct gpiomtd, base));
+}
+
 static void gpio_nand_remove(struct platform_device *pdev)
 {
 	struct gpiomtd *gpiomtd = platform_get_drvdata(pdev);
@@ -273,13 +278,14 @@ static void gpio_nand_remove(struct platform_device *pdev)
 
 	ret = mtd_device_unregister(nand_to_mtd(chip));
 	WARN_ON(ret);
-	nand_cleanup(chip);
+	nand_disconnect(chip);
 
 	/* Enable write protection and disable the chip */
 	if (gpiomtd->nwp && !IS_ERR(gpiomtd->nwp))
 		gpiod_set_value(gpiomtd->nwp, 0);
 	if (gpiomtd->nce && !IS_ERR(gpiomtd->nce))
 		gpiod_set_value(gpiomtd->nce, 0);
+	mtd_put_master(nand_to_mtd(chip));
 }
 
 static int gpio_nand_probe(struct platform_device *pdev)
@@ -294,9 +300,12 @@ static int gpio_nand_probe(struct platform_device *pdev)
 	if (!dev->of_node && !dev_get_platdata(dev))
 		return -EINVAL;
 
-	gpiomtd = devm_kzalloc(dev, sizeof(*gpiomtd), GFP_KERNEL);
+	gpiomtd = kzalloc_obj(*gpiomtd);
 	if (!gpiomtd)
 		return -ENOMEM;
+	ret = devm_nand_controller_init(dev, &gpiomtd->base, gpio_nand_release);
+	if (ret)
+		return ret;
 
 	chip = &gpiomtd->nand_chip;
 
@@ -345,7 +354,6 @@ static int gpio_nand_probe(struct platform_device *pdev)
 		goto out_ce;
 	}
 
-	nand_controller_init(&gpiomtd->base);
 	gpiomtd->base.ops = &gpio_nand_ops;
 
 	nand_set_flash_node(chip, pdev->dev.of_node);
@@ -374,11 +382,18 @@ static int gpio_nand_probe(struct platform_device *pdev)
 
 	if (gpiomtd->plat.adjust_parts)
 		gpiomtd->plat.adjust_parts(&gpiomtd->plat, mtd->size);
+	ret = nand_set_release(chip, NULL);
+	if (ret) {
+		nand_cleanup(chip);
+		goto err_wp;
+	}
 
 	ret = mtd_device_register(mtd, gpiomtd->plat.parts,
 				  gpiomtd->plat.num_parts);
 	if (!ret)
 		return 0;
+	nand_disconnect(chip);
+	mtd_put_master(mtd);
 
 err_wp:
 	if (gpiomtd->nwp && !IS_ERR(gpiomtd->nwp))

-- 
2.53.0