drgn.helpers.linux.wait: document that waitqueue_for_each_task() can …

…return garbage for special wait queues For example, struct blk_mq_hw_ctx::dispatch_wait always has a NULL private pointer, and struct kyber_hctx_data::domain_wait sets the private pointer to a struct blk_mq_hw_ctx. Signed-off-by: Omar Sandoval <[email protected]>
osandov · Dec 1, 2023 · 8ed2403 · 8ed2403
1 parent e6f43c9
commit 8ed2403
Showing 1 changed file with 6 additions and 0 deletions.
diff --git a/drgn/helpers/linux/wait.py b/drgn/helpers/linux/wait.py
@@ -73,6 +73,12 @@ def waitqueue_for_each_task(wq: Object) -> Iterator[Object]:
     """
     Iterate over all tasks waiting on a wait queue.
 
+    .. warning::
+
+        This comes from ``wait_queue_entry_t::private``, which usually stores a
+        task. However, some wait queue entries store a different pointer type,
+        in which case this will return garbage.
+
     :param wq: ``wait_queue_head_t *``
     :return: Iterator of ``struct task_struct *`` objects.
     """