From: Joonwon Kang <joonwonkang@google.com>
Date: Sun, 10 May 2026 05:41:11 +0000 (+0000)
Subject: mailbox: Make mbox_send_message() return error code when tx fails
X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=96a3d2f3167f5644b30e60171898e67123c3c2c6;p=thirdparty%2Fkernel%2Flinux.git

mailbox: Make mbox_send_message() return error code when tx fails

When the mailbox controller failed transmitting message, the error code
was only passed to the client's tx done handler and not to
mbox_send_message() in blocking mode. For this reason, the function could
return a false success. This commit resolves the issue by introducing the
tx status and checking it before mbox_send_message() returns.

This commit works with the premise that the multi-threads' access to a
channel in blocking mode is serialized by clients, not by the mailbox
APIs, since the current mbox_send_message() in blocking mode does not
support multi-threads.

Signed-off-by: Joonwon Kang <joonwonkang@google.com>
Reviewed-by: Sudeep Holla <sudeep.holla@kernel.org>
Signed-off-by: Jassi Brar <jassisinghbrar@gmail.com>
---

diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c
index b00f7a32e8661..066702e5a46f3 100644
--- a/drivers/mailbox/mailbox.c
+++ b/drivers/mailbox/mailbox.c
@@ -98,8 +98,10 @@ static void tx_tick(struct mbox_chan *chan, int r)
 	if (chan->cl->tx_done)
 		chan->cl->tx_done(chan->cl, mssg, r);
 
-	if (r != -ETIME && chan->cl->tx_block)
+	if (r != -ETIME && chan->cl->tx_block) {
+		chan->tx_status = r;
 		complete(&chan->tx_complete);
+	}
 }
 
 static enum hrtimer_restart txdone_hrtimer(struct hrtimer *hrtimer)
@@ -295,6 +297,8 @@ int mbox_send_message(struct mbox_chan *chan, void *mssg)
 		if (ret == 0) {
 			t = -ETIME;
 			tx_tick(chan, t);
+		} else if (chan->tx_status < 0) {
+			t = chan->tx_status;
 		}
 	}
 
diff --git a/include/linux/mailbox_controller.h b/include/linux/mailbox_controller.h
index dc93287a2a01a..26a238a6f941c 100644
--- a/include/linux/mailbox_controller.h
+++ b/include/linux/mailbox_controller.h
@@ -120,6 +120,7 @@ struct mbox_controller {
  * @txdone_method:	Way to detect TXDone chosen by the API
  * @cl:			Pointer to the current owner of this channel
  * @tx_complete:	Transmission completion
+ * @tx_status:		Transmission status
  * @active_req:		Currently active request hook
  * @msg_count:		No. of mssg currently queued
  * @msg_free:		Index of next available mssg slot
@@ -132,6 +133,7 @@ struct mbox_chan {
 	unsigned txdone_method;
 	struct mbox_client *cl;
 	struct completion tx_complete;
+	int tx_status;
 	void *active_req;
 	unsigned msg_count, msg_free;
 	void *msg_data[MBOX_TX_QUEUE_LEN];