From patchwork Fri Jul 7 10:04:24 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Kalle Valo X-Patchwork-Id: 785417 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3x3qwC3gdgz9s75 for ; Fri, 7 Jul 2017 20:04:43 +1000 (AEST) Authentication-Results: ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=qca.qualcomm.com header.i=@qca.qualcomm.com header.b="Goz3No/L"; dkim-atps=neutral Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751196AbdGGKEc (ORCPT ); Fri, 7 Jul 2017 06:04:32 -0400 Received: from alexa-out.qualcomm.com ([129.46.98.28]:6456 "EHLO alexa-out-lv-02.qualcomm.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750768AbdGGKE3 (ORCPT ); Fri, 7 Jul 2017 06:04:29 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=qca.qualcomm.com; i=@qca.qualcomm.com; q=dns/txt; s=qcdkim; t=1499421870; x=1530957870; h=from:to:cc:subject:date:message-id:references: in-reply-to:content-id:content-transfer-encoding: mime-version; bh=JR7PXeXnnW6tJP9VmnD5sGby+EVcusJuwahEJepzRVM=; b=Goz3No/LvfJYbaUIUQuaADDgxn0tYTAdv4YqIsadRDmbZ7hJ1DgeLrRI 3Zuf3P3jzPAG5VS/nuj+eiVJ62/go887OY+W2s4cl6L+59roWk7ucUXpI h0xSw06Ld4ie5cvqa6h/1dph1m9uaDQiJM4b+ummmDJ4ItpY8FNmORMEu 4=; X-IronPort-AV: E=Sophos;i="5.40,322,1496127600"; d="scan'208";a="411874" Received: from ironmsg04-l-new.qualcomm.com (HELO Ironmsg04-L.qualcomm.com) ([10.53.140.111]) by alexa-out-lv-02.qualcomm.com with ESMTP; 07 Jul 2017 03:04:29 -0700 X-IronPort-AV: E=McAfee;i="5800,7501,8583"; a="1382888915" X-MGA-submission: =?us-ascii?q?MDE5VHQ/5CKHQkwvjGypubP+lN8I8nUvWpxpcp?= =?us-ascii?q?j/jyVofZ0LlkupF8W0FOmLJXQ/JzUi+X/rhymAQlbrBakhpyJLlSDUxO?= =?us-ascii?q?gm/v81c2oJ0ewep5DWNd92ko0za1o6XvfyR0DS9iV32z+oSCj/Gdse+w?= =?us-ascii?q?rX?= Received: from nasanexm02a.na.qualcomm.com ([10.85.0.41]) by Ironmsg04-L.qualcomm.com with ESMTP/TLS/RC4-SHA; 07 Jul 2017 03:04:28 -0700 Received: from euamsexm01e.eu.qualcomm.com (10.251.127.42) by nasanexm02a.na.qualcomm.com (10.85.0.41) with Microsoft SMTP Server (TLS) id 15.0.1178.4; Fri, 7 Jul 2017 03:04:28 -0700 Received: from euamsexm01a.eu.qualcomm.com (10.251.127.40) by euamsexm01e.eu.qualcomm.com (10.251.127.42) with Microsoft SMTP Server (TLS) id 15.0.1178.4; Fri, 7 Jul 2017 12:04:24 +0200 Received: from euamsexm01a.eu.qualcomm.com ([10.251.127.40]) by euamsexm01a.eu.qualcomm.com ([10.251.127.40]) with mapi id 15.00.1178.000; Fri, 7 Jul 2017 12:04:24 +0200 From: Kalle Valo To: Erik Stromdahl CC: Geert Uytterhoeven , Arnd Bergmann , "ath10k@lists.infradead.org" , linux-wireless , "netdev@vger.kernel.org" , Linux Kernel Mailing List Subject: Re: ath10k: ret used but uninitialized Thread-Topic: ath10k: ret used but uninitialized Thread-Index: AQHS9whp4PtXL3F45UqCL+3Dc/PNhA== Date: Fri, 7 Jul 2017 10:04:24 +0000 Message-ID: <87bmowd0mh.fsf@kamboji.qca.qualcomm.com> References: In-Reply-To: (Erik Stromdahl's message of "Thu, 6 Jul 2017 22:01:57 +0200") Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-messagesentrepresentingtype: 1 x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.251.52.12] Content-ID: <3A66E09684FF0242BCD94863EA28B1E8@qualcomm.com> MIME-Version: 1.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Erik Stromdahl writes: >> With gcc 4.1.2: >> >> drivers/net/wireless/ath/ath10k/sdio.c: In function >> ‘ath10k_sdio_mbox_rxmsg_pending_handler’: >> drivers/net/wireless/ath/ath10k/sdio.c:676: warning: ‘ret’ may be used >> uninitialized in this function >> >>> + >>> + *done = true; >>> + >>> + /* Copy the lookahead obtained from the HTC register table into our >>> + * temp array as a start value. >>> + */ >>> + lookaheads[0] = msg_lookahead; >>> + >>> + timeout = jiffies + SDIO_MBOX_PROCESSING_TIMEOUT_HZ; >> >> Although very unlikely due to the long timeout, if the code is preempted here, >> and the loop below never entered, ret will indeed be uninitialized. >> >> It's unclear to me what the proper initialization would be, though, so >> that's why I didn't send a patch. >> > I think it would be best to use 0 as initial value of ret in this case. > This will make all other interrupts be processed in a normal way. > > Kalle: Should I create a new patch (initializing ret with zero)? Yes, please send a new patch fixing this. But I don't like that much with the style of initialising ret to zero, it tends to hide things. Instead my preference is something like below where the error handling is more explicit and easier to find where it's exactly failing. But that's just an example how I would try to solve it, it still lacks the handling of -ECANCEL etc. -- Kalle Valo diff --git a/drivers/net/wireless/ath/ath10k/sdio.c b/drivers/net/wireless/ath/ath10k/sdio.c index 859ed870bd97..19a53e577932 100644 --- a/drivers/net/wireless/ath/ath10k/sdio.c +++ b/drivers/net/wireless/ath/ath10k/sdio.c @@ -689,8 +689,10 @@ static int ath10k_sdio_mbox_rxmsg_pending_handler(struct ath10k *ar, */ ret = ath10k_sdio_mbox_rx_alloc(ar, lookaheads, n_lookaheads); - if (ret) - break; + if (ret) { + ath10k_warn(ar, "failed to ....: %d", ret); + return ret; + } if (ar_sdio->n_rx_pkts >= 2) /* A recv bundle was detected, force IRQ status @@ -709,8 +711,10 @@ static int ath10k_sdio_mbox_rxmsg_pending_handler(struct ath10k *ar, lookaheads, &n_lookaheads); - if (!n_lookaheads || ret) - break; + if (!n_lookaheads || ret) { + ath10k_warn(ar, "failed to ...."); + return ret; + } /* For SYNCH processing, if we get here, we are running * through the loop again due to updated lookaheads. Set @@ -721,11 +725,7 @@ static int ath10k_sdio_mbox_rxmsg_pending_handler(struct ath10k *ar, *done = false; } - if (ret && (ret != -ECANCELED)) - ath10k_warn(ar, "failed to get pending recv messages: %d\n", - ret); - - return ret; + return 0; } static int ath10k_sdio_mbox_proc_dbg_intr(struct ath10k *ar)