[PATCH v2 06/13] mailbox: change protection mechanisms

[Suman Anna]

From: Loic Pallardy <loic.pallardy@xxxxxx>

TX: replace spin by mutex to release CPU
during wait on mailbox resource.

Signed-off-by: Loic Pallardy <loic.pallardy@xxxxxx>
Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
---
 drivers/mailbox/mailbox.c          | 5 +++--
 drivers/mailbox/mailbox_internal.h | 1 +
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c
index 6b43e7c..ff6595a 100644
--- a/drivers/mailbox/mailbox.c
+++ b/drivers/mailbox/mailbox.c
@@ -94,7 +94,7 @@ int mailbox_msg_send(struct mailbox *mbox, struct mailbox_msg *msg)
 	struct mailbox_queue *mq = mbox->txq;
 	int ret = 0, len;
 
-	spin_lock_bh(&mq->lock);
+	mutex_lock(&mq->mlock);
 
 	if (kfifo_avail(&mq->fifo) < (sizeof(msg) + msg->size)) {
 		ret = -ENOMEM;
@@ -118,7 +118,7 @@ int mailbox_msg_send(struct mailbox *mbox, struct mailbox_msg *msg)
 	tasklet_schedule(&mbox->txq->tasklet);
 
 out:
-	spin_unlock_bh(&mq->lock);
+	mutex_unlock(&mq->mlock);
 	return ret;
 }
 EXPORT_SYMBOL(mailbox_msg_send);
@@ -289,6 +289,7 @@ static struct mailbox_queue *mbox_queue_alloc(struct mailbox *mbox,
 		return NULL;
 
 	spin_lock_init(&mq->lock);
+	mutex_init(&mq->mlock);
 
 	if (kfifo_alloc(&mq->fifo, mbox_kfifo_size, GFP_KERNEL))
 		goto error;
diff --git a/drivers/mailbox/mailbox_internal.h b/drivers/mailbox/mailbox_internal.h
index ba03910..04f83bf 100644
--- a/drivers/mailbox/mailbox_internal.h
+++ b/drivers/mailbox/mailbox_internal.h
@@ -45,6 +45,7 @@ struct mailbox_ops {
 
 struct mailbox_queue {
 	spinlock_t              lock;
+	struct mutex		mlock;
 	struct kfifo            fifo;
 	struct work_struct      work;
 	struct tasklet_struct   tasklet;
-- 
1.8.1.2

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