From cc8424074e51355e0c6ba717d8edc50d408f2802 Mon Sep 17 00:00:00 2001
From: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Date: Mon, 15 Feb 2016 19:12:09 +0200
Subject: stm class: Plug stm device's unlink callback

STM device's unlink callback is never actually called from anywhere in
the stm class code.

This patch adds calls to stm driver's unlink method after the unlinking
has succeeded.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/hwtracing/stm/core.c b/drivers/hwtracing/stm/core.c
index 3018182..de80d45 100644
--- a/drivers/hwtracing/stm/core.c
+++ b/drivers/hwtracing/stm/core.c
@@ -376,14 +376,19 @@ err_free:
 static int stm_char_release(struct inode *inode, struct file *file)
 {
 	struct stm_file *stmf = file->private_data;
+	struct stm_device *stm = stmf->stm;
+
+	if (stm->data->unlink)
+		stm->data->unlink(stm->data, stmf->output.master,
+				  stmf->output.channel);
 
-	stm_output_free(stmf->stm, &stmf->output);
+	stm_output_free(stm, &stmf->output);
 
 	/*
 	 * matches the stm_char_open()'s
 	 * class_find_device() + try_module_get()
 	 */
-	stm_put_device(stmf->stm);
+	stm_put_device(stm);
 	kfree(stmf);
 
 	return 0;
@@ -865,8 +870,18 @@ unlock:
 	spin_unlock(&src->link_lock);
 	spin_unlock(&stm->link_lock);
 
-	if (!ret && src->data->unlink)
-		src->data->unlink(src->data);
+	/*
+	 * Call the unlink callbacks for both source and stm, when we know
+	 * that we have actually performed the unlinking.
+	 */
+	if (!ret) {
+		if (src->data->unlink)
+			src->data->unlink(src->data);
+
+		if (stm->data->unlink)
+			stm->data->unlink(stm->data, src->output.master,
+					  src->output.channel);
+	}
 
 	return ret;
 }
diff --git a/include/linux/stm.h b/include/linux/stm.h
index ab8ceca..1a79ed8 100644
--- a/include/linux/stm.h
+++ b/include/linux/stm.h
@@ -74,6 +74,9 @@ struct stm_device;
  *      it must return zero;
  *   3) if it does not support the requested packet type/flag combination,
  *      it must return -ENOTSUPP.
+ *
+ * The @unlink callback is called when there are no more active writers so
+ * that the master/channel can be quiesced.
  */
 struct stm_data {
 	const char		*name;
-- 
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