amd_pmc_verify_czn_rtc() opens the RTC with rtc_class_open(), which
takes both a device reference and a module reference on the RTC
driver. The matching release is rtc_class_close(), and it is never
called. Every return path after the device has been opened, the ones
that return 0 as well as the ones that report an error, leaves both
references behind, so each S0i3 suspend leaks them.

Release the reference with a __free() cleanup on the declaration,
which covers every return path without adding labels.

rtc_class_close() does not accept a NULL argument, so the cleanup
helper has to guard against one: rtc_class_open() may fail and the
declaration still has to be cleaned up.

Found by code review.

Fixes: 59348401ebed ("platform/x86: amd-pmc: Add special handling for timer based S0i3 wakeup")
Cc: stable@vger.kernel.org
Signed-off-by: Ma Ke <make_ruc2021@163.com>
---
Changes in v3:
- Define DEFINE_FREE(rtc_class_close, ...) in include/linux/rtc.h rather
  than locally in pmc.c, since it belongs with the API it wraps.
  Suggested by Ilpo Järvinen.
- Guard the cleanup against a NULL rtc_device; rtc_class_close() does not
  handle one.
- Move the __free() declaration to the assignment, as described in the
  comment in <linux/cleanup.h>.
- Cc the RTC maintainer and list, since v3 touches include/linux/rtc.h.

Changes in v2:
- Replace the added goto labels with a __free() cleanup on the
  declaration, as suggested by Mario Limonciello and Ilpo Järvinen.
---
 drivers/platform/x86/amd/pmc/pmc.c | 5 +++--
 include/linux/rtc.h                | 2 ++
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/platform/x86/amd/pmc/pmc.c b/drivers/platform/x86/amd/pmc/pmc.c
index 6792aa2c6187..f96e8a358eb7 100644
--- a/drivers/platform/x86/amd/pmc/pmc.c
+++ b/drivers/platform/x86/amd/pmc/pmc.c
@@ -14,6 +14,7 @@
 #include <linux/array_size.h>
 #include <linux/bitfield.h>
 #include <linux/bits.h>
+#include <linux/cleanup.h>
 #include <linux/debugfs.h>
 #include <linux/delay.h>
 #include <linux/dmi.h>
@@ -648,7 +649,6 @@ static int amd_pmc_wa_irq1(struct amd_pmc_dev *pdev)
 
 static int amd_pmc_verify_czn_rtc(struct amd_pmc_dev *pdev, u32 *arg)
 {
-	struct rtc_device *rtc_device;
 	time64_t then, now, duration;
 	struct rtc_wkalrm alarm;
 	struct rtc_time tm;
@@ -664,7 +664,8 @@ static int amd_pmc_verify_czn_rtc(struct amd_pmc_dev *pdev, u32 *arg)
 	if (pdev->major < 64 || (pdev->major == 64 && pdev->minor < 53))
 		return 0;
 
-	rtc_device = rtc_class_open("rtc0");
+	struct rtc_device *rtc_device __free(rtc_class_close) =
+		rtc_class_open("rtc0");
 	if (!rtc_device)
 		return 0;
 	rc = rtc_read_next_alarm(rtc_device, &alarm);
diff --git a/include/linux/rtc.h b/include/linux/rtc.h
index c09fc22819d0..0f43b5027235 100644
--- a/include/linux/rtc.h
+++ b/include/linux/rtc.h
@@ -13,6 +13,7 @@
 #define _LINUX_RTC_H_
 
 
+#include <linux/cleanup.h>
 #include <linux/types.h>
 #include <linux/interrupt.h>
 #include <linux/nvmem-provider.h>
@@ -201,6 +202,7 @@ extern void rtc_update_irq(struct rtc_device *rtc,
 
 extern struct rtc_device *rtc_class_open(const char *name);
 extern void rtc_class_close(struct rtc_device *rtc);
+DEFINE_FREE(rtc_class_close, struct rtc_device *, if (_T) rtc_class_close(_T));
 
 extern int rtc_irq_set_state(struct rtc_device *rtc, int enabled);
 extern int rtc_irq_set_freq(struct rtc_device *rtc, int freq);
-- 
2.43.0