[PATCH 2/2] drm/xe: Release runtime pm for error path of xe_devcoredump_read()

[Shuicheng Lin]

xe_pm_runtime_put() is missed to be called for the error path in
xe_devcoredump_read().
Add function description comments for xe_devcoredump_read() to help
understand it.

Fixes: c4a2e5f865b7 ("drm/xe: Add devcoredump chunking")
Cc: Matthew Brost <matthew.brost at intel.com>
Signed-off-by: Shuicheng Lin <shuicheng.lin at intel.com>
---
 drivers/gpu/drm/xe/xe_devcoredump.c | 32 +++++++++++++++++++++++------
 1 file changed, 26 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_devcoredump.c b/drivers/gpu/drm/xe/xe_devcoredump.c
index 94625010abc4..701ffe6c8264 100644
--- a/drivers/gpu/drm/xe/xe_devcoredump.c
+++ b/drivers/gpu/drm/xe/xe_devcoredump.c
@@ -171,14 +171,29 @@ static void xe_devcoredump_snapshot_free(struct xe_devcoredump_snapshot *ss)
 
 #define XE_DEVCOREDUMP_CHUNK_MAX	(SZ_512M + SZ_1G)
 
+/**
+ * xe_devcoredump_read - Read data from the Xe device coredump snapshot
+ * @buffer: Destination buffer to copy the coredump data into
+ * @offset: Offset in the coredump data to start reading from
+ * @count: Number of bytes to read
+ * @data: Pointer to the xe_devcoredump structure
+ * @datalen: Length of the data (unused)
+ *
+ * Reads a chunk of the coredump snapshot data into the provided buffer,
+ * handling chunked reads for large coredumps and ensuring proper locking.
+ *
+ * Return: Number of bytes copied on success, or a negative error code on failure.
+ */
 static ssize_t xe_devcoredump_read(char *buffer, loff_t offset,
 				   size_t count, void *data, size_t datalen)
 {
 	struct xe_devcoredump *coredump = data;
 	struct xe_devcoredump_snapshot *ss;
-	ssize_t byte_copied;
+	ssize_t byte_copied = 0;
 	u32 chunk_offset;
 	ssize_t new_chunk_position;
+	bool pm_acquired = false;
+	int ret = 0;
 
 	if (!coredump)
 		return -ENODEV;
@@ -188,19 +203,23 @@ static ssize_t xe_devcoredump_read(char *buffer, loff_t offset,
 	/* Ensure delayed work is captured before continuing */
 	flush_work(&ss->work);
 
-	if (ss->read.size > XE_DEVCOREDUMP_CHUNK_MAX)
+	if (ss->read.size > XE_DEVCOREDUMP_CHUNK_MAX) {
 		xe_pm_runtime_get(gt_to_xe(ss->gt));
+		pm_acquired = true;
+	}
 
 	mutex_lock(&coredump->lock);
 
 	if (!ss->read.buffer) {
 		mutex_unlock(&coredump->lock);
-		return -ENODEV;
+		ret = -ENODEV;
+		goto pm_put;
 	}
 
 	if (offset >= ss->read.size) {
 		mutex_unlock(&coredump->lock);
-		return 0;
+		ret = 0;
+		goto pm_put;
 	}
 
 	new_chunk_position = div_u64_rem(offset,
@@ -223,10 +242,11 @@ static ssize_t xe_devcoredump_read(char *buffer, loff_t offset,
 
 	mutex_unlock(&coredump->lock);
 
-	if (ss->read.size > XE_DEVCOREDUMP_CHUNK_MAX)
+pm_put:
+	if (pm_acquired)
 		xe_pm_runtime_put(gt_to_xe(ss->gt));
 
-	return byte_copied;
+	return byte_copied ? byte_copied : ret;
 }
 
 static void xe_devcoredump_free(void *data)
-- 
2.49.0