From patchwork Sat Jan 23 00:24:22 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Maxim Levitsky X-Patchwork-Id: 43554 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 2EC36B7CCD for ; Sat, 23 Jan 2010 11:27:23 +1100 (EST) Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.69 #1 (Red Hat Linux)) id 1NYTng-0005RF-FC; Sat, 23 Jan 2010 00:24:28 +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 1NYTnd-0005B4-Vm for linux-mtd@lists.infradead.org; Sat, 23 Jan 2010 00:24:26 +0000 Received: by mail-bw0-f212.google.com with SMTP id 4so1645861bwz.2 for ; Fri, 22 Jan 2010 16:24:25 -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=OYOURO+orv8a/rfoa1q8fiDC3KxXk2o9o/juzqsMY/Q=; b=GtY+EpbFvGcYxGF6PWOVzkzoYQ8LVNKh+P5AfH4WwwhBsHXbKXo71fFHmmQbN1twrO zcIuE4nVE8/vi6dwp/I7zr35J+If19JzC4CmXhx6+nZEqKbaglry3pkXjVBUQ1xjk+dw Euo2dBFlJiBCPMtZNzZypF1IFKtVKwNIP7WKE= 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=i5FZu3ffYhENxr42LvF9KOUBWngFufQr3IWFuAKAa3qu1flLEpXFSRByeZ/LeqQLUv 7yDzRJmTpWPhqqFMaCF5OFbKp8f8IXwL2H7rsf82xVy31/pgRK9pjDjnusJf3Iyx2IJ6 U6Q6SqOJkD9Cta/BBjAPNdYex0VoFWRr3dxHU= Received: by 10.204.23.20 with SMTP id p20mr2067678bkb.54.1264206265493; Fri, 22 Jan 2010 16:24:25 -0800 (PST) Received: from ?10.1.0.2? ([87.70.246.165]) by mx.google.com with ESMTPS id 14sm1243658bwz.1.2010.01.22.16.24.23 (version=SSLv3 cipher=RC4-MD5); Fri, 22 Jan 2010 16:24:25 -0800 (PST) Subject: [PATCH 5/8] blktrans: add proper locking 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 02:24:22 +0200 Message-ID: <1264206262.31827.9.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_192426_200960_8DA5D56E X-CRM114-Status: GOOD ( 22.38 ) 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 695c50a575ba7e004931e234f4706766be507289 Mon Sep 17 00:00:00 2001 From: Maxim Levitsky Date: Sat, 23 Jan 2010 02:07:53 +0200 Subject: [PATCH 5/8] blktrans: add proper locking First, use lockless versions of get/put_mtd_device We don't care what happened to mtd table, because we have a pointer to mtd device. It guaranteed to exist till we do final put_mtd_device Also add locking to prevent all kinds or races Signed-off-by: Maxim Levitsky --- drivers/mtd/mtd_blkdevs.c | 83 ++++++++++++++++++++++++++++---------------- 1 files changed, 53 insertions(+), 30 deletions(-) diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c index c95e1ff..f165115 100644 --- a/drivers/mtd/mtd_blkdevs.c +++ b/drivers/mtd/mtd_blkdevs.c @@ -123,34 +123,34 @@ static int blktrans_open(struct block_device *bdev, fmode_t mode) { struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data; struct mtd_blktrans_ops *tr = dev->tr; - int ret = -ENODEV; - - if (!get_mtd_device(NULL, dev->mtd->index)) - goto out; + int ret = 0; + mutex_lock(&dev->lock); if (dev->open++) goto out; if (dev->deleted) goto out; - + ret = -ENODEV; if (!try_module_get(tr->owner)) - goto out_tr; + goto out; + + if (__get_mtd_device(dev->mtd)) { + module_put(tr->owner); + goto out; + } - /* FIXME: Locking. A hot pluggable device can go away - (del_mtd_device can be called for it) without its module - being unloaded. */ - dev->mtd->usecount++; ret = 0; if (tr->open && (ret = tr->open(dev))) { - dev->mtd->usecount--; - put_mtd_device(dev->mtd); - out_tr: module_put(tr->owner); + __put_mtd_device(dev->mtd); + goto out; + } out: + mutex_unlock(&dev->lock); return ret; } @@ -160,18 +160,11 @@ static int blktrans_release(struct gendisk *disk, fmode_t mode) struct mtd_blktrans_ops *tr = dev->tr; int ret = 0; + mutex_lock(&dev->lock); dev->open--; if (dev->open) return 0; - if (tr->release) - ret = tr->release(dev); - - if (!ret) { - dev->mtd->usecount--; - put_mtd_device(dev->mtd); - module_put(tr->owner); - } /* Free the private data */ if (dev->deleted) { @@ -181,33 +174,59 @@ static int blktrans_release(struct gendisk *disk, fmode_t mode) return 0; } + ret = tr->release ? tr->release(dev) : 0; + module_put(tr->owner); + + if (dev->mtd) + __put_mtd_device(dev->mtd); +out: + mutex_unlock(&dev->lock); return ret; } static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo) { struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data; + int error; + + mutex_lock(&dev->lock); + error = -ENODEV; + if (dev->deleted) + goto out; + + error = -ENOTTY; if (dev->tr->getgeo) - return dev->tr->getgeo(dev, geo); - return -ENOTTY; + error = dev->tr->getgeo(dev, geo); +out: + mutex_unlock(&dev->lock); + return error; } static int blktrans_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd, unsigned long arg) { struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data; - struct mtd_blktrans_ops *tr = dev->tr; + int error = -ENODEV; + + mutex_lock(&dev->lock); + + if (dev->deleted) + goto out; + + error = -ENOTTY; switch (cmd) { case BLKFLSBUF: - if (tr->flush) - return tr->flush(dev); - /* The core code did the work, we had nothing to do. */ - return 0; + if (dev->tr->flush) + error = dev->tr->flush(dev); + break; default: - return -ENOTTY; + break; } +out: + mutex_unlock(&dev->lock); + return error; } static const struct block_device_operations mtd_blktrans_ops = { @@ -355,15 +374,19 @@ int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old) /* Stop the thread */ kthread_stop(old->thread); + /* Tell trans driver to release the device */ + mutex_lock(&old->lock); + if (old->open) { if (old->tr->release) old->tr->release(old); - put_mtd_device(old->mtd); + __put_mtd_device(old->mtd); } /* From now on, no calls into trans can be made */ /* Mtd device will be gone real soon now */ old->mtd = NULL; + mutex_unlock(&old->lock); blk_cleanup_queue(old->rq);