The patch below does not apply to the 5.15-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 stable@vger.kernel.org.
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-5.15.y git checkout FETCH_HEAD git cherry-pick -x 1f73b8b56cf35de29a433aee7bfff26cea98be3f # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025120110-deuce-arrange-e66c@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 1f73b8b56cf35de29a433aee7bfff26cea98be3f Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?=C5=81ukasz=20Bartosik?= ukaszb@chromium.org Date: Wed, 19 Nov 2025 21:29:09 +0000 Subject: [PATCH] xhci: dbgtty: fix device unregister MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit
When DbC is disconnected then xhci_dbc_tty_unregister_device() is called. However if there is any user space process blocked on write to DbC terminal device then it will never be signalled and thus stay blocked indifinitely.
This fix adds a tty_vhangup() call in xhci_dbc_tty_unregister_device(). The tty_vhangup() wakes up any blocked writers and causes subsequent write attempts to DbC terminal device to fail.
Cc: stable stable@kernel.org Fixes: dfba2174dc42 ("usb: xhci: Add DbC support in xHCI driver") Signed-off-by: Łukasz Bartosik ukaszb@chromium.org Link: https://patch.msgid.link/20251119212910.1245694-1-ukaszb@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
diff --git a/drivers/usb/host/xhci-dbgtty.c b/drivers/usb/host/xhci-dbgtty.c index b7f95565524d..57cdda4e09c8 100644 --- a/drivers/usb/host/xhci-dbgtty.c +++ b/drivers/usb/host/xhci-dbgtty.c @@ -550,6 +550,12 @@ static void xhci_dbc_tty_unregister_device(struct xhci_dbc *dbc)
if (!port->registered) return; + /* + * Hang up the TTY. This wakes up any blocked + * writers and causes subsequent writes to fail. + */ + tty_vhangup(port->port.tty); + tty_unregister_device(dbc_tty_driver, port->minor); xhci_dbc_tty_exit_port(port); port->registered = false;