From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A897BC3F2C6 for ; Tue, 10 Mar 2020 13:34:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 75D6320675 for ; Tue, 10 Mar 2020 13:34:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583847283; bh=TmISeBl+z/riu5zI1Aow+4OtmrTWBLBSDho4zHJx+0g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=gDAZWkHngTzUrC7oXWHW1SmfEMfxFyt8drHdw11nR/S9gHgxYzQpiYquxChtyHyc3 xGE+x3TghVOAKX+L/dvIRtPIl1MKUNYShKJJ1Adn59b1hzYihvhyIWRjB1EgeeETT+ BEeU46izapfBjWDRoRULwY2IGiv7BLh/NWwMNsCw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726731AbgCJMqI (ORCPT ); Tue, 10 Mar 2020 08:46:08 -0400 Received: from mail.kernel.org ([198.145.29.99]:49012 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727722AbgCJMqG (ORCPT ); Tue, 10 Mar 2020 08:46:06 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 270B224696; Tue, 10 Mar 2020 12:46:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583844365; bh=TmISeBl+z/riu5zI1Aow+4OtmrTWBLBSDho4zHJx+0g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=vB5LMzaAiR8/queMPFHGeq+B+5eQt+nr4BmAvYG7s7eRD9D4Ts9077ucBUrfgxJlT 0QudpRm5UUs64zfajwN++ZD9tb0AyOb0SloILk+DfgoPsWnMopW0WZg7gk0VJ6vJbl XdEm0jSC4anL6I3N20hGtBcEd7Z+WvPdsk4invlM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sergey Organov , =?UTF-8?q?Micha=C5=82=20Miros=C5=82aw?= , Felipe Balbi , Sasha Levin Subject: [PATCH 4.9 54/88] usb: gadget: serial: fix Tx stall after buffer overflow Date: Tue, 10 Mar 2020 13:39:02 +0100 Message-Id: <20200310123619.619783130@linuxfoundation.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200310123606.543939933@linuxfoundation.org> References: <20200310123606.543939933@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Sergey Organov [ Upstream commit e4bfded56cf39b8d02733c1e6ef546b97961e18a ] Symptom: application opens /dev/ttyGS0 and starts sending (writing) to it while either USB cable is not connected, or nobody listens on the other side of the cable. If driver circular buffer overflows before connection is established, no data will be written to the USB layer until/unless /dev/ttyGS0 is closed and re-opened again by the application (the latter besides having no means of being notified about the event of establishing of the connection.) Fix: on open and/or connect, kick Tx to flush circular buffer data to USB layer. Signed-off-by: Sergey Organov Reviewed-by: Michał Mirosław Signed-off-by: Felipe Balbi Signed-off-by: Sasha Levin --- drivers/usb/gadget/function/u_serial.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c index 510a54f889635..5d7d0f2e80a5e 100644 --- a/drivers/usb/gadget/function/u_serial.c +++ b/drivers/usb/gadget/function/u_serial.c @@ -715,8 +715,10 @@ static int gs_start_io(struct gs_port *port) port->n_read = 0; started = gs_start_rx(port); - /* unblock any pending writes into our circular buffer */ if (started) { + gs_start_tx(port); + /* Unblock any pending writes into our circular buffer, in case + * we didn't in gs_start_tx() */ tty_wakeup(port->port.tty); } else { gs_free_requests(ep, head, &port->read_allocated); -- 2.20.1