From patchwork Tue Sep 22 11:21:20 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Oliver Neukum X-Patchwork-Id: 258452 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=-12.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, 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 15E98C4727D for ; Tue, 22 Sep 2020 11:21:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AF5622388B for ; Tue, 22 Sep 2020 11:21:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="XGqEUDXY" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726578AbgIVLV6 (ORCPT ); Tue, 22 Sep 2020 07:21:58 -0400 Received: from mx2.suse.de ([195.135.220.15]:37322 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726454AbgIVLVw (ORCPT ); Tue, 22 Sep 2020 07:21:52 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1600773710; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:in-reply-to:in-reply-to:references:references; bh=2uWvnpc3bmPq2wl5EDlk5vxdx9IFG3yUbr1P4YdA22Y=; b=XGqEUDXYCWlfarTkTCSiNrs+9Ira5kwfsfmAL1RSXehIzZ1hs7bS/MyBmc8viji7BSGLOo y9rboFvu37+Ldy5L4bErPsD7U2QlTcXOqfvwykk0iVPdBRcVD9uelGxSdMp8I5b9qH7Ds5 GXpGIxNQpSEXRHkNGe6gZGEStoslGG4= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id C08BFAD63; Tue, 22 Sep 2020 11:22:26 +0000 (UTC) From: Oliver Neukum To: penguin-kernel@i-love.sakura.ne.jp, bjorn@mork.no, linux-usb@vger.kernel.org Cc: Oliver Neukum Subject: [RFC 1/7] CDC-WDM: fix hangs in flush() in multithreaded cases Date: Tue, 22 Sep 2020 13:21:20 +0200 Message-Id: <20200922112126.16919-2-oneukum@suse.com> X-Mailer: git-send-email 2.16.4 In-Reply-To: <20200922112126.16919-1-oneukum@suse.com> References: <20200922112126.16919-1-oneukum@suse.com> Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org In a multithreaded scenario an arbitrary number of threads can be in wdm_write() and in wdm_flush(). Hence whenever WDM_IN_USE is reset, all possible waiters need to be notified. This is true whether this is due to IO completing or to an error starting IO. Reported-by: Tetsuo Handa Signed-off-by: Oliver Neukum --- drivers/usb/class/cdc-wdm.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/drivers/usb/class/cdc-wdm.c b/drivers/usb/class/cdc-wdm.c index e3db6fbeadef..adb3fc307083 100644 --- a/drivers/usb/class/cdc-wdm.c +++ b/drivers/usb/class/cdc-wdm.c @@ -151,7 +151,7 @@ static void wdm_out_callback(struct urb *urb) kfree(desc->outbuf); desc->outbuf = NULL; clear_bit(WDM_IN_USE, &desc->flags); - wake_up(&desc->wait); + wake_up_all(&desc->wait); } static void wdm_in_callback(struct urb *urb) @@ -424,6 +424,7 @@ static ssize_t wdm_write if (rv < 0) { desc->outbuf = NULL; clear_bit(WDM_IN_USE, &desc->flags); + wake_up_all(&desc->wait); /* for flush() */ dev_err(&desc->intf->dev, "Tx URB error: %d\n", rv); rv = usb_translate_errors(rv); goto out_free_mem_pm; @@ -586,6 +587,7 @@ static ssize_t wdm_read static int wdm_flush(struct file *file, fl_owner_t id) { struct wdm_device *desc = file->private_data; + int rv; wait_event(desc->wait, /* @@ -600,11 +602,12 @@ static int wdm_flush(struct file *file, fl_owner_t id) /* cannot dereference desc->intf if WDM_DISCONNECTING */ if (test_bit(WDM_DISCONNECTING, &desc->flags)) return -ENODEV; - if (desc->werr < 0) + rv = desc->werr; + if (rv < 0) dev_err(&desc->intf->dev, "Error in flush path: %d\n", - desc->werr); + rv); - return usb_translate_errors(desc->werr); + return usb_translate_errors(rv); } static __poll_t wdm_poll(struct file *file, struct poll_table_struct *wait)