[PATCH] hwrng: cctrng: fix usage_count leak when autosuspend_delay is negative

[Guangshuo Li <lgs201920130244@gmail.com>]

cc_trng_pm_init() calls pm_runtime_use_autosuspend(), but
cc_trng_pm_fini() does not call the matching
pm_runtime_dont_use_autosuspend() before disabling runtime PM.

If the autosuspend delay is set to a negative value while autosuspend
is enabled, the runtime PM core increments usage_count to prevent
runtime suspend. Without calling pm_runtime_dont_use_autosuspend()
during teardown, this reference is not dropped and usage_count remains
unbalanced.

Add the missing pm_runtime_dont_use_autosuspend() call before disabling
runtime PM.

This issue was found by manual code inspection.

Fixes: a583ed310bb6 ("hwrng: cctrng - introduce Arm CryptoCell driver")
Cc: stable@vger.kernel.org
Signed-off-by: Guangshuo Li <lgs201920130244@gmail.com>
---
 drivers/char/hw_random/cctrng.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/char/hw_random/cctrng.c b/drivers/char/hw_random/cctrng.c
index a5be9258037f..bed4b9876d09 100644
--- a/drivers/char/hw_random/cctrng.c
+++ b/drivers/char/hw_random/cctrng.c
@@ -126,6 +126,7 @@ static void cc_trng_pm_fini(struct cctrng_drvdata *drvdata)
 {
 	struct device *dev = &(drvdata->pdev->dev);
 
+	pm_runtime_dont_use_autosuspend(dev);
 	pm_runtime_disable(dev);
 }
 
-- 
2.43.0