[PATCH] rtc: mpc5121: convert from irq_of_parse_and_map to platform_get_irq

[Rosen Penev]

irq_of_parse_and_map() is an OF-specific low-level function that
requires the caller to pair it with irq_dispose_mapping(). Mixing
it with devm_request_irq() creates a lifecycle hazard — the probe
error path and remove both dispose the mapping while the managed
free_irq is still pending, leading to a dangling descriptor use in
free_irq().

Switch to platform_get_irq(), which is the standard interface for
platform devices. It returns a negative errno on failure, integrates
with platform resource lookup, and eliminates the need for explicit
irq_dispose_mapping() calls since the IRQ domain core manages the
mapping lifecycle. This lets us drop the error labels and simplify
both probe and remove.

Remove these irq variables from the private struct. They were
originally used to free the irq in _remove. devm has replaced that.

Assisted-by: opencode:big-pickle
Signed-off-by: Rosen Penev <rosenp@xxxxxxxxx>

m
---
 drivers/rtc/rtc-mpc5121.c | 59 ++++++++++++++-------------------------
 1 file changed, 21 insertions(+), 38 deletions(-)

diff --git a/drivers/rtc/rtc-mpc5121.c b/drivers/rtc/rtc-mpc5121.c
index b90f8337a7e6..964d9594b1d7 100644
--- a/drivers/rtc/rtc-mpc5121.c
+++ b/drivers/rtc/rtc-mpc5121.c
@@ -11,7 +11,6 @@
 #include <linux/module.h>
 #include <linux/rtc.h>
 #include <linux/of.h>
-#include <linux/of_irq.h>
 #include <linux/platform_device.h>
 #include <linux/io.h>
 #include <linux/slab.h>
@@ -72,8 +71,6 @@ struct mpc5121_rtc_regs {
 };
 
 struct mpc5121_rtc_data {
-	unsigned irq;
-	unsigned irq_periodic;
 	struct mpc5121_rtc_regs __iomem *regs;
 	struct rtc_device *rtc;
 	struct rtc_wkalrm wkalarm;
@@ -292,6 +289,16 @@ static int mpc5121_rtc_probe(struct platform_device *op)
 {
 	struct mpc5121_rtc_data *rtc;
 	int err = 0;
+	int irq_periodic;
+	int irq;
+
+	irq = platform_get_irq(op, 1);
+	if (irq < 0)
+		return irq;
+
+	irq_periodic = platform_get_irq(op, 0);
+	if (irq_periodic < 0)
+		return irq_periodic;
 
 	rtc = devm_kzalloc(&op->dev, sizeof(*rtc), GFP_KERNEL);
 	if (!rtc)
@@ -307,30 +314,20 @@ static int mpc5121_rtc_probe(struct platform_device *op)
 
 	platform_set_drvdata(op, rtc);
 
-	rtc->irq = irq_of_parse_and_map(op->dev.of_node, 1);
-	err = devm_request_irq(&op->dev, rtc->irq, mpc5121_rtc_handler, 0,
+	err = devm_request_irq(&op->dev, irq, mpc5121_rtc_handler, 0,
 			       "mpc5121-rtc", &op->dev);
-	if (err) {
-		dev_err(&op->dev, "%s: could not request irq: %i\n",
-							__func__, rtc->irq);
-		goto out_dispose;
-	}
+	if (err)
+		return err;
 
-	rtc->irq_periodic = irq_of_parse_and_map(op->dev.of_node, 0);
-	err = devm_request_irq(&op->dev, rtc->irq_periodic,
-			       mpc5121_rtc_handler_upd, 0, "mpc5121-rtc_upd",
-			       &op->dev);
-	if (err) {
-		dev_err(&op->dev, "%s: could not request irq: %i\n",
-						__func__, rtc->irq_periodic);
-		goto out_dispose2;
-	}
+	err = devm_request_irq(&op->dev, irq_periodic,
+			       mpc5121_rtc_handler_upd, 0,
+			       "mpc5121-rtc_upd", &op->dev);
+	if (err)
+		return err;
 
 	rtc->rtc = devm_rtc_allocate_device(&op->dev);
-	if (IS_ERR(rtc->rtc)) {
-		err = PTR_ERR(rtc->rtc);
-		goto out_dispose2;
-	}
+	if (IS_ERR(rtc->rtc))
+		return PTR_ERR(rtc->rtc);
 
 	rtc->rtc->ops = &mpc5200_rtc_ops;
 	set_bit(RTC_FEATURE_ALARM_RES_MINUTE, rtc->rtc->features);
@@ -356,18 +353,7 @@ static int mpc5121_rtc_probe(struct platform_device *op)
 		rtc->rtc->range_max = U32_MAX;
 	}
 
-	err = devm_rtc_register_device(rtc->rtc);
-	if (err)
-		goto out_dispose2;
-
-	return 0;
-
-out_dispose2:
-	irq_dispose_mapping(rtc->irq_periodic);
-out_dispose:
-	irq_dispose_mapping(rtc->irq);
-
-	return err;
+	return devm_rtc_register_device(rtc->rtc);
 }
 
 static void mpc5121_rtc_remove(struct platform_device *op)
@@ -378,9 +364,6 @@ static void mpc5121_rtc_remove(struct platform_device *op)
 	/* disable interrupt, so there are no nasty surprises */
 	out_8(&regs->alm_enable, 0);
 	out_8(&regs->int_enable, in_8(&regs->int_enable) & ~0x1);
-
-	irq_dispose_mapping(rtc->irq);
-	irq_dispose_mapping(rtc->irq_periodic);
 }
 
 #ifdef CONFIG_OF
-- 
2.55.0