From patchwork Sat Jan 23 00:23:52 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Maxim Levitsky X-Patchwork-Id: 43552 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from bombadil.infradead.org (bombadil.infradead.org [18.85.46.34]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id EAD04B7CB9 for ; Sat, 23 Jan 2010 11:25:23 +1100 (EST) Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.69 #1 (Red Hat Linux)) id 1NYTnH-0005E6-JC; Sat, 23 Jan 2010 00:24:03 +0000 Received: from mail-bw0-f212.google.com ([209.85.218.212]) by bombadil.infradead.org with esmtp (Exim 4.69 #1 (Red Hat Linux)) id 1NYTnA-0005B4-HU for linux-mtd@lists.infradead.org; Sat, 23 Jan 2010 00:24:01 +0000 Received: by bwz4 with SMTP id 4so1645861bwz.2 for ; Fri, 22 Jan 2010 16:23:55 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:subject:from:to:cc :in-reply-to:references:content-type:date:message-id:mime-version :x-mailer:content-transfer-encoding; bh=eaM/+fbZ3eeTZ3glCY8JOl3pyYSIcrkh0/OqcwWLTSE=; b=RHhubLwid/Jw+fYv7TfFtS1v9P+qpdL8ZHJeUF9enm8AcPD4TqgQJlnrXKPRFJzAB7 4NV8WAxzBb1hdzHXdzFF74o6bdMj/FKz/vXYXU/rFoi34O5Ckeyg/VmYrEzNN4KbkIwa k9aZs3EDn5Zvm7N/iACF75WHVVjGjhDAKiPmo= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=subject:from:to:cc:in-reply-to:references:content-type:date :message-id:mime-version:x-mailer:content-transfer-encoding; b=IZ3mMai7vV2z38VUDU7RyYrfGNVnkFP8yTSbL+N6Cxy6NWFafxtpGKtN1IgMR0ySFP k+bRL6MHRBCaYn5E0v7yojtGqBL6x+do2efG3vsT0TJPm0URVNykvgyuGB0FQj4WjFx2 gvTcPAgWFGhNumk+e1sCwWdpEhZ3xq+Whp0Mw= Received: by 10.204.18.211 with SMTP id x19mr1996160bka.116.1264206235833; Fri, 22 Jan 2010 16:23:55 -0800 (PST) Received: from ?10.1.0.2? ([87.70.246.165]) by mx.google.com with ESMTPS id 13sm1232587bwz.10.2010.01.22.16.23.53 (version=SSLv3 cipher=RC4-MD5); Fri, 22 Jan 2010 16:23:55 -0800 (PST) Subject: [PATCH 4/8] MTD: create lockless versions of {get,put}_mtd_device From: Maxim Levitsky To: Artem Bityutskiy In-Reply-To: <1264205925.31827.3.camel@maxim-laptop> References: <1264205925.31827.3.camel@maxim-laptop> Date: Sat, 23 Jan 2010 02:23:52 +0200 Message-ID: <1264206232.31827.8.camel@maxim-laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.1 X-CRM114-Version: 20090807-BlameThorstenAndJenny ( TRE 0.7.6 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20100122_192356_784257_E9359127 X-CRM114-Status: GOOD ( 17.67 ) X-Spam-Score: 0.0 (/) X-Spam-Report: SpamAssassin version 3.2.5 on bombadil.infradead.org summary: Content analysis details: (0.0 points) pts rule name description ---- ---------------------- -------------------------------------------------- _SUMMARY_ Cc: Alex Dubov , joern , linux-kernel , linux-mtd , Thomas Gleixner , David Woodhouse X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-mtd-bounces@lists.infradead.org Errors-To: linux-mtd-bounces+incoming=patchwork.ozlabs.org@lists.infradead.org >From b7c27159b5540b0951f6b030ffca895f34a3b3d3 Mon Sep 17 00:00:00 2001 From: Maxim Levitsky Date: Sat, 23 Jan 2010 02:04:44 +0200 Subject: [PATCH 4/8] MTD: create lockless versions of {get,put}_mtd_device This will be used to resolve deadlock in block translation layer. Signed-off-by: Maxim Levitsky --- drivers/mtd/mtdcore.c | 60 ++++++++++++++++++++++++++++++---------------- include/linux/mtd/mtd.h | 3 +- 2 files changed, 41 insertions(+), 22 deletions(-) diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c index c356c0a..3bdb7e8 100644 --- a/drivers/mtd/mtdcore.c +++ b/drivers/mtd/mtdcore.c @@ -453,27 +453,38 @@ struct mtd_info *get_mtd_device(struct mtd_info *mtd, int num) ret = NULL; } - if (!ret) - goto out_unlock; - - if (!try_module_get(ret->owner)) - goto out_unlock; - - if (ret->get_device) { - err = ret->get_device(ret); - if (err) - goto out_put; + if (!ret) { + ret = ERR_PTR(err); + goto out; } - ret->usecount++; + err = __get_mtd_device(ret); + if (err) + ret = ERR_PTR(err); +out: mutex_unlock(&mtd_table_mutex); return ret; +} -out_put: - module_put(ret->owner); -out_unlock: - mutex_unlock(&mtd_table_mutex); - return ERR_PTR(err); + +int __get_mtd_device(struct mtd_info *mtd) +{ + int err; + + if (!try_module_get(mtd->owner)) + return -ENODEV; + + if (mtd->get_device) { + + err = mtd->get_device(mtd); + + if (err) { + module_put(mtd->owner); + return err; + } + } + mtd->usecount++; + return 0; } /** @@ -524,14 +535,19 @@ out_unlock: void put_mtd_device(struct mtd_info *mtd) { - int c; - mutex_lock(&mtd_table_mutex); - c = --mtd->usecount; + __put_mtd_device(mtd); + mutex_unlock(&mtd_table_mutex); + +} + +void __put_mtd_device(struct mtd_info *mtd) +{ + --mtd->usecount; + BUG_ON(mtd->usecount < 0); + if (mtd->put_device) mtd->put_device(mtd); - mutex_unlock(&mtd_table_mutex); - BUG_ON(c < 0); module_put(mtd->owner); } @@ -569,7 +585,9 @@ EXPORT_SYMBOL_GPL(add_mtd_device); EXPORT_SYMBOL_GPL(del_mtd_device); EXPORT_SYMBOL_GPL(get_mtd_device); EXPORT_SYMBOL_GPL(get_mtd_device_nm); +EXPORT_SYMBOL_GPL(__get_mtd_device); EXPORT_SYMBOL_GPL(put_mtd_device); +EXPORT_SYMBOL_GPL(__put_mtd_device); EXPORT_SYMBOL_GPL(register_mtd_user); EXPORT_SYMBOL_GPL(unregister_mtd_user); EXPORT_SYMBOL_GPL(default_mtd_writev); diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h index 0f32a9b..662d747 100644 --- a/include/linux/mtd/mtd.h +++ b/include/linux/mtd/mtd.h @@ -290,8 +290,9 @@ extern int add_mtd_device(struct mtd_info *mtd); extern int del_mtd_device (struct mtd_info *mtd); extern struct mtd_info *get_mtd_device(struct mtd_info *mtd, int num); +extern int __get_mtd_device(struct mtd_info *mtd); +extern void __put_mtd_device(struct mtd_info *mtd); extern struct mtd_info *get_mtd_device_nm(const char *name); - extern void put_mtd_device(struct mtd_info *mtd);