module/dups: Inform duplicate requests about the result directly

When kmod_dup_request_announce() announces the completion of a request_module() call to duplicate waiters, it queues a work item to invoke kmod_dup_request_complete(), and only that function calls complete_all(). This adds an arbitrary delay that is unnecessary and provides little benefit. Call complete_all() directly from kmod_dup_request_announce() instead.

Petr Pavlu committed 3 months ago

Commit d258ed81 parent da991301 file · +9 −34Browse files

Unified · Split

kernel/module/dups.c+9−34

 	struct list_head list;
 	char name[MODULE_NAME_LEN];
 	struct completion first_req_done;
-	struct work_struct complete_work;
 	struct delayed_work delete_work;
 	int dup_ret;
 };
 	kfree(kmod_req);
 }
-static void kmod_dup_request_complete(struct work_struct *work)
-{
-	struct kmod_dup_req *kmod_req;
-	kmod_req = container_of(work, struct kmod_dup_req, complete_work);
-	/*
-	 * This will ensure that the kernel will let all the waiters get
-	 * informed its time to check the return value. It's time to
-	 * go home.
-	 */
-	complete_all(&kmod_req->first_req_done);
-	/*
-	 * Now that we have allowed prior request_module() calls to go on
-	 * with life, let's schedule deleting this entry. We don't have
-	 * to do it right away, but we *eventually* want to do it so to not
-	 * let this linger forever as this is just a boot optimization for
-	 * possible abuses of vmalloc() incurred by finit_module() thrashing.
-	 */
-	queue_delayed_work(system_dfl_wq, &kmod_req->delete_work, 60 * HZ);
-}
 bool kmod_dup_request_exists_wait(char *module_name, bool wait, int *dup_ret)
 {
 	struct kmod_dup_req *kmod_req, *new_kmod_req;
 		return false;
 	strscpy(new_kmod_req->name, module_name);
-	INIT_WORK(&new_kmod_req->complete_work, kmod_dup_request_complete);
 	INIT_DELAYED_WORK(&new_kmod_req->delete_work, kmod_dup_request_delete);
 	init_completion(&new_kmod_req->first_req_done);
 	kmod_req->dup_ret = ret;
+	/* Inform all duplicate waiters to check the return value. */
+	complete_all(&kmod_req->first_req_done);
 	/*
-	 * If we complete() here we may allow duplicate threads
+	 * Now that we have allowed prior request_module() calls to go on
-	 * to continue before the first one that submitted the
+	 * with life, let's schedule deleting this entry. We don't have
-	 * request. We're in no rush also, given that each and
+	 * to do it right away, but we *eventually* want to do it so to not
-	 * every bounce back to userspace is slow we avoid that
+	 * let this linger forever as this is just a boot optimization for
-	 * with a slight delay here. So queueue up the completion
+	 * possible abuses of vmalloc() incurred by finit_module() thrashing.
-	 * and let duplicates suffer, just wait a tad bit longer.
-	 * There is no rush. But we also don't want to hold the
-	 * caller up forever or introduce any boot delays.
 	 */
-	queue_work(system_dfl_wq, &kmod_req->complete_work);
+	queue_delayed_work(system_dfl_wq, &kmod_req->delete_work, 60 * HZ);
 out:
 	mutex_unlock(&kmod_dup_mutex);