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[2620:137:e000::1:20]) by mx.google.com with ESMTP id ds3-20020a170907724300b0078cdba56108si4658467ejc.296.2022.12.24.08.36.13; Sat, 24 Dec 2022 08:36:36 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=fail header.i=@mailo.com header.s=mailo header.b=PEQeobYk; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=mailo.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231293AbiLXQeJ (ORCPT + 99 others); Sat, 24 Dec 2022 11:34:09 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50440 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229688AbiLXQeH (ORCPT ); Sat, 24 Dec 2022 11:34:07 -0500 Received: from msg-1.mailo.com (msg-1.mailo.com [213.182.54.11]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 67242BC24; Sat, 24 Dec 2022 08:34:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=mailo.com; s=mailo; t=1671899635; bh=lZPFgAklaDMM/Nar0joqKweC5S5QgeTAOuf+S5eqA54=; h=X-EA-Auth:Date:From:To:Cc:Subject:Message-ID:References: MIME-Version:Content-Type:In-Reply-To; b=PEQeobYkPHBvsQf1uYxPjVZCr5MDrzYQbm30/dqzXCxDsDshfAYWe/8YKPTKh5r+H ML+EvdZCkgfCpFwY5UNGsY+Sm5hg36YyH9d++1KS7SAW+qArwjQWDBnQQ+NcoMZo9C 4U9QHm8dpR+tHec57wRWfIT1nfaQdI4Ts6+yKnTs= Received: by b-4.in.mailobj.net [192.168.90.14] with ESMTP via ip-206.mailobj.net [213.182.55.206] Sat, 24 Dec 2022 17:33:55 +0100 (CET) X-EA-Auth: KoErFyzIxepLC6/uiq781G29rTyZ7tEIEuiqF35jeYbUL5AI27FCTgRYKDO1jWYUk5i2hvlmx46SY09VhqDEcSR4FSyBbACE Date: Sat, 24 Dec 2022 22:03:48 +0530 From: Deepak R Varma To: "Maciej W. Rozycki" , Greg Kroah-Hartman , Jiri Slaby , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Saurabh Singh Sengar , Praveen Kumar , Deepak R Varma Subject: [PATCH v3 1/2] tty: serial: dz: convert atomic_* to refcount_* APIs for map_guard Message-ID: References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1753114000484655642?= X-GMAIL-MSGID: =?utf-8?q?1753114000484655642?= The refcount_* APIs are designed to address known issues with the atomic_t APIs for reference counting. They provide following distinct advantages - protect the reference counters from overflow/underflow - avoid use-after-free errors - provide improved memory ordering guarantee schemes - neater and safer. Hence, replace the atomic_* APIs by their equivalent refcount_t API functions. This patch proposal address the following warnings generated by the atomic_as_refcounter.cocci coccinelle script atomic_add_return(-1, ...) Signed-off-by: Deepak R Varma --- Please Note: 1. The patch is compile tested using dec_station.defconfig for MIPS architecture. 2. This patch should be applied before patch 2/2 of this series due to dependency. Changes in v3: 1. Include the individual patches in a series and highlight dependency. Feedback provided by gregkh@linuxfoundation.org Changes in v2: 1. Separate the combined change into one variable per patch as suggested by gregkh@linuxfoundation.org 2. There was additional feedback on validating the change as it appeared to modify the existing logic. However, I found that the logic does not change with the proposed refcount_* APIs used in this change. Hence that feedback is not applied in this version. drivers/tty/serial/dz.c | 23 +++++++++-------------- 1 file changed, 9 insertions(+), 14 deletions(-) -- 2.34.1 diff --git a/drivers/tty/serial/dz.c b/drivers/tty/serial/dz.c index 6b7ed7f2f3ca..b70edc248f8b 100644 --- a/drivers/tty/serial/dz.c +++ b/drivers/tty/serial/dz.c @@ -47,6 +47,7 @@ #include #include +#include #include #include @@ -75,7 +76,7 @@ struct dz_port { struct dz_mux { struct dz_port dport[DZ_NB_PORT]; - atomic_t map_guard; + refcount_t map_guard; atomic_t irq_guard; int initialised; }; @@ -662,13 +663,11 @@ static const char *dz_type(struct uart_port *uport) static void dz_release_port(struct uart_port *uport) { struct dz_mux *mux = to_dport(uport)->mux; - int map_guard; iounmap(uport->membase); uport->membase = NULL; - map_guard = atomic_add_return(-1, &mux->map_guard); - if (!map_guard) + if (refcount_dec_and_test(&mux->map_guard)) release_mem_region(uport->mapbase, dec_kn_slot_size); } @@ -687,23 +686,19 @@ static int dz_map_port(struct uart_port *uport) static int dz_request_port(struct uart_port *uport) { struct dz_mux *mux = to_dport(uport)->mux; - int map_guard; int ret; - map_guard = atomic_add_return(1, &mux->map_guard); - if (map_guard == 1) { - if (!request_mem_region(uport->mapbase, dec_kn_slot_size, - "dz")) { - atomic_add(-1, &mux->map_guard); - printk(KERN_ERR - "dz: Unable to reserve MMIO resource\n"); + refcount_inc(&mux->map_guard); + if (refcount_read(&mux->map_guard) == 1) { + if (!request_mem_region(uport->mapbase, dec_kn_slot_size, "dz")) { + refcount_dec(&mux->map_guard); + printk(KERN_ERR "dz: Unable to reserve MMIO resource\n"); return -EBUSY; } } ret = dz_map_port(uport); if (ret) { - map_guard = atomic_add_return(-1, &mux->map_guard); - if (!map_guard) + if (refcount_dec_and_test(&mux->map_guard)) release_mem_region(uport->mapbase, dec_kn_slot_size); return ret; } From patchwork Sat Dec 24 16:34:28 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Deepak R Varma X-Patchwork-Id: 36436 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a5d:4e01:0:0:0:0:0 with SMTP id p1csp223588wrt; Sat, 24 Dec 2022 08:37:12 -0800 (PST) X-Google-Smtp-Source: AMrXdXsy/xBTTWDMdJoLBb8crqWwc39yIc6DdqwC59myo/WujsFBDrPSso4O37d3DiPWce2x/nzW X-Received: by 2002:aa7:d689:0:b0:461:7ae:c244 with SMTP id d9-20020aa7d689000000b0046107aec244mr10969398edr.35.1671899832390; Sat, 24 Dec 2022 08:37:12 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1671899832; cv=none; d=google.com; s=arc-20160816; b=TqUfW9cppxRIfmNXqFQMiNChUpPmSWxrQxhYUPKZxIjrLdbvf68Sxu8IkgXfhaVRW8 ZBGsd8beuHg+yoO8n0sguFRjr7YQDDT+qNg0XNlWv1BwQBy73ll+15BEgUKZ5RU84Dox 5tutSuYxYX9HJAsLuQtvsC/mSGqI0ALGMdPdQv1Cy6QR257XKRh4MJ02SCujvs0xP+U8 Tmy94bW8Lq4gZbAbGjUy4858gLrSAnS08BG/KHrgZGmos/GrQauHO6qXbLqNRHZoJQRY M4+hi71SM82UgQtdGSVGoryI5Tw/aCqvLROW31j6ofVz+IZtvntnW9AOTcxfb+Q0FCcu ku+w== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:in-reply-to:content-disposition:mime-version :references:message-id:subject:cc:to:from:date:dkim-signature; bh=9SGPV5x0O0HFpoHdnBS8U8scQ6sfEaHibETRS6fZA+Y=; b=Js6FS+j+9iC3QQmcfgh4hDBvae3mbTbhmzl1+JSNB7MUyJ+DYKuJID73QScBeX0j3R gqdzV3O3iCM2U/22O1p3tOUZvvjYYXkb6GIh+yZaHqLGV9aF/dtqjEuxbYe6jokMogs1 ol6965Wu1ZMSPtH/okFLc4eNLUQJfSc22Hb05+H/tWN2VhivFJ/9xJNCuKgeAHygqCKv CxN5roknDKNAENlsm43rBzv40iT/CsTGUUeWSmdfML+n6yNvXbiXW8Iyzrx+LQR86pF8 oXsKQAViQ7v5WYtuAHzpW9pBQrMQUE9T0frvwvlS5RIBv+11usg6JrgorbkEu4y/bs3G 9dug== ARC-Authentication-Results: i=1; mx.google.com; dkim=fail header.i=@mailo.com header.s=mailo header.b=G7fRU4wG; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=mailo.com Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id t2-20020a05640203c200b004825e4a6946si2961235edw.371.2022.12.24.08.36.49; Sat, 24 Dec 2022 08:37:12 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=fail header.i=@mailo.com header.s=mailo header.b=G7fRU4wG; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=mailo.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231317AbiLXQeo (ORCPT + 99 others); Sat, 24 Dec 2022 11:34:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50694 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229688AbiLXQem (ORCPT ); Sat, 24 Dec 2022 11:34:42 -0500 Received: from msg-2.mailo.com (msg-2.mailo.com [213.182.54.12]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 72BF6BC24; Sat, 24 Dec 2022 08:34:41 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=mailo.com; s=mailo; t=1671899673; bh=JOlABxyXfYqHNmeXEA2u7PKdxsmIADwnMI+IIPAofYs=; h=X-EA-Auth:Date:From:To:Cc:Subject:Message-ID:References: MIME-Version:Content-Type:In-Reply-To; b=G7fRU4wGfAc6gzasYNgExIne6OeHxLd2yQwgYqH9UVM9hGaioJ7GT+snkxYaZHzmF T9rz25g8S5NVnzAC5x63nQIRo7d0WY5dNkAVSHrJJct00oswLDiQ/RkyEtlq3STeTa A/YzBd4wTuc4D//7kxpGMBaj/TN4pLeXbOQkf9ns= Received: by b-4.in.mailobj.net [192.168.90.14] with ESMTP via ip-206.mailobj.net [213.182.55.206] Sat, 24 Dec 2022 17:34:33 +0100 (CET) X-EA-Auth: u5gVJF6h2z6ranrprLxW6HFUwyiomyX6r//ovjc1j/VosSoEw1Ak2Lw/JbyumNnUO9AM56Ey8DrPTbNA0EQfj9lOo+WcqNpx Date: Sat, 24 Dec 2022 22:04:28 +0530 From: Deepak R Varma To: "Maciej W. Rozycki" , Greg Kroah-Hartman , Jiri Slaby , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Saurabh Singh Sengar , Praveen Kumar , Deepak R Varma Subject: [PATCH 2/2] tty: serial: dz: convert atomic_* to refcount_* APIs for irq_guard Message-ID: <51ef854f77779c82010379420139993e12c38776.1671898144.git.drv@mailo.com> References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1753114038974437835?= X-GMAIL-MSGID: =?utf-8?q?1753114038974437835?= The refcount_* APIs are designed to address known issues with the atomic_t APIs for reference counting. They provide following distinct advantages: - protect the reference counters from overflow/underflow - avoid use-after-free errors - provide improved memory ordering guarantee schemes - neater and safer. Hence, replace the atomic_* APIs by their equivalent refcount_t API functions. This patch proposal address the following warnings generated by the atomic_as_refcounter.cocci coccinelle script atomic_add_return(-1, ...) Signed-off-by: Deepak R Varma --- Please Note: 1. The patch is compile tested using dec_station.defconfig for MIPS architecture. 2. This patch should be applied after patch 1/2 of this series due to dependency. Changes in v3: 1. Include the individual patches in a series and highlight dependency. Feedback provided by gregkh@linuxfoundation.org Changes in v2: 1. Separate the combined change into one variable per patch as suggested by gregkh@linuxfoundation.org drivers/tty/serial/dz.c | 17 ++++++----------- 1 file changed, 6 insertions(+), 11 deletions(-) -- 2.34.1 diff --git a/drivers/tty/serial/dz.c b/drivers/tty/serial/dz.c index b70edc248f8b..0aa59a9beeb7 100644 --- a/drivers/tty/serial/dz.c +++ b/drivers/tty/serial/dz.c @@ -46,7 +46,6 @@ #include #include -#include #include #include #include @@ -77,7 +76,7 @@ struct dz_port { struct dz_mux { struct dz_port dport[DZ_NB_PORT]; refcount_t map_guard; - atomic_t irq_guard; + refcount_t irq_guard; int initialised; }; @@ -400,18 +399,16 @@ static int dz_startup(struct uart_port *uport) struct dz_port *dport = to_dport(uport); struct dz_mux *mux = dport->mux; unsigned long flags; - int irq_guard; int ret; u16 tmp; - irq_guard = atomic_add_return(1, &mux->irq_guard); - if (irq_guard != 1) + refcount_inc(&mux->irq_guard); + if (refcount_read(&mux->irq_guard) != 1) return 0; - ret = request_irq(dport->port.irq, dz_interrupt, - IRQF_SHARED, "dz", mux); + ret = request_irq(dport->port.irq, dz_interrupt, IRQF_SHARED, "dz", mux); if (ret) { - atomic_add(-1, &mux->irq_guard); + refcount_dec(&mux->irq_guard); printk(KERN_ERR "dz: Cannot get IRQ %d!\n", dport->port.irq); return ret; } @@ -441,15 +438,13 @@ static void dz_shutdown(struct uart_port *uport) struct dz_port *dport = to_dport(uport); struct dz_mux *mux = dport->mux; unsigned long flags; - int irq_guard; u16 tmp; spin_lock_irqsave(&dport->port.lock, flags); dz_stop_tx(&dport->port); spin_unlock_irqrestore(&dport->port.lock, flags); - irq_guard = atomic_add_return(-1, &mux->irq_guard); - if (!irq_guard) { + if (refcount_dec_and_test(&mux->irq_guard)) { /* Disable interrupts. */ tmp = dz_in(dport, DZ_CSR); tmp &= ~(DZ_RIE | DZ_TIE);