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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 308B3C3F2D2 for ; Tue, 3 Mar 2020 02:49:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F21C324684 for ; Tue, 3 Mar 2020 02:49:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583203745; bh=1Ab1FCoddUe1BX9XPSIJ0DoL+dXn+oXOQ+sECh6PTO0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Q8JracOlbIn5Y5YFHIXh/DB43Bn/ueK0Bt1rfukIv7pSaxpS5lS8+glKYDmwYiLfk TMNVTac9duECbD9yWN+H+/gx3r/t4ZIz6jNx/LmMKlys8WEJZO8fzD/IwP0vQ42fJo 8D09/hPGmlTtY8uIL2r4cXQ1gw9RGCD84APqX2GY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728645AbgCCCtC (ORCPT ); Mon, 2 Mar 2020 21:49:02 -0500 Received: from mail.kernel.org ([198.145.29.99]:44948 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728637AbgCCCtB (ORCPT ); Mon, 2 Mar 2020 21:49:01 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id EFF4F246BB; Tue, 3 Mar 2020 02:48:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583203740; bh=1Ab1FCoddUe1BX9XPSIJ0DoL+dXn+oXOQ+sECh6PTO0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GRSNiAb0NXPkFVZqAIqhk6CY8uaOnyYxDtYA/qgLr2V2AEsvgN6S6+JBjqrwcy6nL fhJqEuYrOvRDVAb7uCu4yA2gNvDdDZgfTX+dqBe1poGHaG6Gf0546eAn99iti8rQYd zQUbkq5XKy0YJ05DCH8SEDWtZo9vWFHE3fP1AbRI= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Sergey Organov , =?UTF-8?q?Micha=C5=82=20Miros=C5=82aw?= , Felipe Balbi , Sasha Levin , linux-usb@vger.kernel.org Subject: [PATCH AUTOSEL 4.19 07/32] usb: gadget: serial: fix Tx stall after buffer overflow Date: Mon, 2 Mar 2020 21:48:26 -0500 Message-Id: <20200303024851.10054-7-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200303024851.10054-1-sashal@kernel.org> References: <20200303024851.10054-1-sashal@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@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 d4d317db89df5..38afe96c5cd26 100644 --- a/drivers/usb/gadget/function/u_serial.c +++ b/drivers/usb/gadget/function/u_serial.c @@ -567,8 +567,10 @@ 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