--- a/drivers/accel/amdxdna/amdxdna_mailbox.c
+++ b/drivers/accel/amdxdna/amdxdna_mailbox.c
@@ -207,26 +207,34 @@ mailbox_send_msg(struct mailbox_channel *mb_chann, struct mailbox_msg *mb_msg)
 	u32 head, tail;
 	u32 start_addr;
 	u32 tmp_tail;
+	int ret;
 
 	head = mailbox_get_headptr(mb_chann, CHAN_RES_X2I);
 	tail = mb_chann->x2i_tail;
-	ringbuf_size = mailbox_get_ringbuf_size(mb_chann, CHAN_RES_X2I);
+	ringbuf_size = mailbox_get_ringbuf_size(mb_chann, CHAN_RES_X2I) - sizeof(u32);
 	start_addr = mb_chann->res[CHAN_RES_X2I].rb_start_addr;
 	tmp_tail = tail + mb_msg->pkg_size;
 
-	if (tail < head && tmp_tail >= head)
-		goto no_space;
-
-	if (tail >= head && (tmp_tail > ringbuf_size - sizeof(u32) &&
-			     mb_msg->pkg_size >= head))
-		goto no_space;
 
-	if (tail >= head && tmp_tail > ringbuf_size - sizeof(u32)) {
+check_again:
+	if (tail >= head && tmp_tail > ringbuf_size) {
 		write_addr = mb_chann->mb->res.ringbuf_base + start_addr + tail;
 		writel(TOMBSTONE, write_addr);
 
 		/* tombstone is set. Write from the start of the ringbuf */
 		tail = 0;
+		tmp_tail = tail + mb_msg->pkg_size;
+	}
+
+	if (tail < head && tmp_tail >= head) {
+		ret = read_poll_timeout(mailbox_get_headptr, head,
+					tmp_tail < head || tail >= head,
+					1, 100, false, mb_chann, CHAN_RES_X2I);
+		if (ret)
+			return ret;
+
+		if (tail >= head)
+			goto check_again;
 	}
 
 	write_addr = mb_chann->mb->res.ringbuf_base + start_addr + tail;
@@ -238,9 +246,6 @@ mailbox_send_msg(struct mailbox_channel *mb_chann, struct mailbox_msg *mb_msg)
 			    mb_msg->pkg.header.id);
 
 	return 0;
-
-no_space:
-	return -ENOSPC;
 }
 
 static int
-- 
2.51.0[PATCH 6.19 207/781] accel/amdxdna: Fix race where send ring appears full due to delayed head updateGreg Kroah-Hartman <gregkh@linuxfoundation.org> undefinedstable@vger.kernel.org undefined undefined undefined undefined undefinedÍM†šN