FAILED: patch "[PATCH] Bluetooth: ISO: release unused CIS holds after channel attach" failed to apply to 6.6-stable tree

The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x 0fcd4dad555c96e0bd3a1b8c569f989be85c7341
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026092937-animate-footing-cd66@gregkh' --subject-prefix 'PATCH 6.6.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 0fcd4dad555c96e0bd3a1b8c569f989be85c7341 Mon Sep 17 00:00:00 2001
From: Aldo Ariel Panzardo <[email protected]>
Date: Tue, 15 Sep 2026 13:04:30 -0300
Subject: [PATCH] Bluetooth: ISO: release unused CIS holds after channel attach

hci_bind_cis() and hci_connect_cis() return one hci_conn hold for the ISO layer. A new channel association consumes that hold, which is eventually released by iso_conn_free().

There are two cases where iso_chan_add() does not create an association:
it returns success when the socket is already attached to the same iso_conn, and it returns -EBUSY when another socket is attached. The hold returned for the current call is unused in both cases. This occurs when deferred setup calls iso_connect_cis() again for its existing socket, or when another socket attempts to reuse the CIS.

Detect the idempotent case while the connection is locked and release the unused hold after iso_chan_add(). Also release it on -EBUSY. Do not drop it for other errors: a newly allocated iso_conn releases the transferred hold when its last temporary reference is put.

index eb99653f33f9..7657c2a0abbf 100644
@@ -496,6 +496,7 @@ static int iso_connect_cis(struct sock *sk)
 	struct hci_dev  *hdev;
 	bdaddr_t src, dst;
 	u8 src_type;
+	bool already_attached;
 	int err;
 
 	lock_sock(sk);

@@ -568,8 +569,14 @@ static int iso_connect_cis(struct sock *sk)
 		goto unlock;
 	}
 
+	iso_conn_lock(conn);
+	already_attached = iso_pi(sk)->conn == conn && conn->sk == sk;
+	iso_conn_unlock(conn);
+
 	err = iso_chan_add(conn, sk, NULL);
 	iso_conn_put(conn);
+	if (already_attached || err == -EBUSY)
+		hci_conn_drop(hcon);
 	if (err)
 		goto unlock;