workqueue: implement current_is_async()

This function queries whether %current is an async worker executing an
async item.  This will be used to implement warning on synchronous
request_module() from async workers.

Signed-off-by: Tejun Heo <tj@kernel.org>

1 files changed, 14 insertions, 0 deletions

diff --git a/kernel/async.c b/kernel/async.c
index 9d3118384858..d9bf2a9b5cee 100644
--- a/kernel/async.c
+++ b/kernel/async.c
@@ -57,6 +57,8 @@ asynchronous and synchronous parts of the kernel.
 #include <linux/slab.h>
 #include <linux/workqueue.h>
 
+#include "workqueue_internal.h"
+
 static async_cookie_t next_cookie = 1;
 
 #define MAX_WORK        32768
@@ -337,3 +339,15 @@ void async_synchronize_cookie(async_cookie_t cookie)
         async_synchronize_cookie_domain(cookie, &async_running);
 }
 EXPORT_SYMBOL_GPL(async_synchronize_cookie);
+
+/**
+ * current_is_async - is %current an async worker task?
+ *
+ * Returns %true if %current is an async worker task.
+ */
+bool current_is_async(void)
+{
+        struct worker *worker = current_wq_worker();
+
+        return worker && worker->current_func == async_run_entry_fn;
+}