[PATCH] rtc: cmos: unregister HPET IRQ handler on probe failure

[Haoxiang Li]

cmos_do_probe() registers cmos_interrupt() as the HPET RTC IRQ
handler before requesting the RTC IRQ and registering the RTC
device. If either request_irq() or devm_rtc_register_device()
fails afterwards, the error path leaves the HPET RTC IRQ handler
installed. This leaves a stale handler behind and make a later
hpet_register_irq_handler() fail with -EBUSY.

Track whether the HPET handler was registered successfully and
undo the registration on the probe error path. Also mask the HPET
RTC IRQ bits to match the normal shutdown cleanup.

Fixes: 9d8af78b0797 ("rtc: add HPET RTC emulation to RTC_DRV_CMOS")
Signed-off-by: Haoxiang Li <haoxiang_li2024@xxxxxxx>
---
 drivers/rtc/rtc-cmos.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/rtc/rtc-cmos.c b/drivers/rtc/rtc-cmos.c
index f89ab58f5048..fa04ece151b8 100644
--- a/drivers/rtc/rtc-cmos.c
+++ b/drivers/rtc/rtc-cmos.c
@@ -934,6 +934,7 @@ cmos_do_probe(struct device *dev, struct resource *ports, int rtc_irq)
 	unsigned char			rtc_control;
 	unsigned			address_space;
 	u32				flags = 0;
+	bool				hpet_registered = false;
 	struct nvmem_config nvmem_cfg = {
 		.name = "cmos_nvram",
 		.word_size = 1,
@@ -1091,6 +1092,7 @@ cmos_do_probe(struct device *dev, struct resource *ports, int rtc_irq)
 						" failed in rtc_init().");
 				goto cleanup1;
 			}
+			hpet_registered = true;
 		} else
 			rtc_cmos_int_handler = cmos_interrupt;
 
@@ -1140,6 +1142,10 @@ cmos_do_probe(struct device *dev, struct resource *ports, int rtc_irq)
 	if (is_valid_irq(rtc_irq))
 		free_irq(rtc_irq, cmos_rtc.rtc);
 cleanup1:
+	if (hpet_registered) {
+		hpet_mask_rtc_irq_bit(RTC_IRQMASK);
+		hpet_unregister_irq_handler(cmos_interrupt);
+	}
 	cmos_rtc.dev = NULL;
 cleanup0:
 	if (RTC_IOMAPPED)
-- 
2.25.1