[PATCH 19/20] stm class: Plug stm device's unlink callback

[Alexander Shishkin <alexander.shishkin@linux.intel.com>]

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>
---
 drivers/hwtracing/stm/core.c | 23 +++++++++++++++++++----
 include/linux/stm.h          |  3 +++
 2 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/drivers/hwtracing/stm/core.c b/drivers/hwtracing/stm/core.c
index 30181821d9..de80d45d8d 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 ab8ceca4f5..1a79ed8e43 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;
-- 
2.7.0