linux-kernel - [PATCH] completion: Document that reinit_completion() must be called after complete

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Message-ID: <20170816112735.0c7d9e1a@gandalf.local.home>
Date:   Wed, 16 Aug 2017 11:27:35 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH] completion: Document that reinit_completion() must be
 called after complete_all()

The function complete_all() modifies the completion "done" variable to
UINT_MAX, and no other caller (wait_for_completion(), etc) will modify
it back to zero. That means that any call to complete_all() must have a
reinit_completion() before that completion can be used again.

Document this fact by the complete_all() function.

Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
---
diff --git a/kernel/sched/completion.c b/kernel/sched/completion.c
index 13fc5ae..cc9d926 100644
--- a/kernel/sched/completion.c
+++ b/kernel/sched/completion.c
@@ -47,6 +47,9 @@ EXPORT_SYMBOL(complete);
  *
  * It may be assumed that this function implies a write memory barrier before
  * changing the task state if and only if any tasks are woken up.
+ *
+ * A call to reinit_completion() must be used on @x if it is to be used
+ * again after this call.
  */
 void complete_all(struct completion *x)
 {