coresight: Check runtime PM resume result

coresight_get_ref() ignores the return value of pm_runtime_get_sync() and reports success even when runtime resume fails. A path is then built and the CoreSight device may be accessed while it remains powered off.

Use pm_runtime_resume_and_get() so a failed resume is reported and its runtime PM usage reference is rolled back. Drop the module and device references acquired before the resume attempt when it fails.

---
Changes in v2:
- Point Fixes: at commit 32b0707a4182, which introduced coresight_get_ref() with the unchecked pm_runtime_get_sync() (Anshuman Khandual)
- Switch to my oss.patchbox address

v1: https://lore.kernel.org/all/[email protected]/

 drivers/hwtracing/coresight/coresight-core.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

index 928488a216d4..c492f9082c46 100644
@@ -843,7 +843,11 @@ static bool coresight_get_ref(struct coresight_device *csdev)
 		goto err_module;
 
 	/* Make sure the device is powered on */
-	pm_runtime_get_sync(parent);
+	if (pm_runtime_resume_and_get(parent) < 0) {
+		module_put(drv->owner);
+		goto err_module;
+	}
+
 	return true;
 
 err_module:

base-commit: f0100363d8c374bd8e9ea7c9ba02744f0b802ca4

2.43.0

Thanks for pointing out the existing patch!