From patchwork Thu Feb 4 23:30:45 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Maxim Levitsky X-Patchwork-Id: 44574 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 C80F1B7CFE for ; Fri, 5 Feb 2010 10:35:16 +1100 (EST) Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.69 #1 (Red Hat Linux)) id 1NdBAa-0007B9-9z; Thu, 04 Feb 2010 23:31:32 +0000 Received: from fg-out-1718.google.com ([72.14.220.158]) by bombadil.infradead.org with esmtp (Exim 4.69 #1 (Red Hat Linux)) id 1NdBAU-00076Y-1t for linux-mtd@lists.infradead.org; Thu, 04 Feb 2010 23:31:30 +0000 Received: by fg-out-1718.google.com with SMTP id 22so15507fge.0 for ; Thu, 04 Feb 2010 15:31:24 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:from:to:cc:subject:date :message-id:x-mailer:in-reply-to:references; bh=17WEp7pfCNVOVSK0BfhWCvAqkiFZ5xN3ubiRT8x4W1E=; b=mbb04xvRwvwUVuIkY2fB2MXY0yJGbfXuXWjsmYbA3eZCszqiTcHu4FXImTutiIB3EN guYUtHCfzz7qbzHdSho+LRHPgsBMv5+k225l8vOPuZ5VpTnpoI0mHZphKBr689/GINJe In/wIJPqDyfWLsk4IldCDx/nKwg0OSuQTPuCE= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=from:to:cc:subject:date:message-id:x-mailer:in-reply-to:references; b=GmHKJO9YcT9pYRqVFtI9EY3yxZttd1Z5fauj2V62hXm/jud594x2ebNVyQ6jFg2HgJ ZR2Kop5EmogT8wRzU5fg2RlOCUiM31jy4ZMaVrYOjCvNhFHAcd+DboyOBkEg9a6dllW4 c6zPYiJif+0+z/iUpoTjfy+mmvWWhtWPhs/mA= Received: by 10.103.122.31 with SMTP id z31mr1188044mum.136.1265326283488; Thu, 04 Feb 2010 15:31:23 -0800 (PST) Received: from localhost.localdomain (IGLD-84-229-248-49.inter.net.il [84.229.248.49]) by mx.google.com with ESMTPS id u9sm3865749muf.18.2010.02.04.15.31.21 (version=SSLv3 cipher=RC4-MD5); Thu, 04 Feb 2010 15:31:22 -0800 (PST) From: Maxim Levitsky To: David Woodhouse Subject: [PATCH 05/17] blktrans: add proper locking Date: Fri, 5 Feb 2010 01:30:45 +0200 Message-Id: <1265326257-4446-6-git-send-email-maximlevitsky@gmail.com> X-Mailer: git-send-email 1.6.3.3 In-Reply-To: <1265326257-4446-1-git-send-email-maximlevitsky@gmail.com> References: <1265326257-4446-1-git-send-email-maximlevitsky@gmail.com> X-CRM114-Version: 20090807-BlameThorstenAndJenny ( TRE 0.7.6 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20100204_183126_379674_FFAC4AA5 X-CRM114-Status: GOOD ( 22.56 ) 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: Maxim Levitsky , Alex Dubov , Artem Bityutskiy , joern , linux-kernel , linux-mtd , Thomas Gleixner 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: , MIME-Version: 1.0 Sender: linux-mtd-bounces@lists.infradead.org Errors-To: linux-mtd-bounces+incoming=patchwork.ozlabs.org@lists.infradead.org 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 | 84 ++++++++++++++++++++++++++++---------------- 1 files changed, 53 insertions(+), 31 deletions(-) diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c index 1b89e59..082969c 100644 --- a/drivers/mtd/mtd_blkdevs.c +++ b/drivers/mtd/mtd_blkdevs.c @@ -123,33 +123,33 @@ 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; - /* 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++; + if (__get_mtd_device(dev->mtd)) { + module_put(tr->owner); + goto out; + } 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; } @@ -159,17 +159,10 @@ static int blktrans_release(struct gendisk *disk, fmode_t mode) struct mtd_blktrans_ops *tr = dev->tr; int ret = 0; + mutex_lock(&dev->lock); if (--dev->open) - return 0; - - if (tr->release) - ret = tr->release(dev); + goto out; - if (!ret) { - dev->mtd->usecount--; - put_mtd_device(dev->mtd); - module_put(tr->owner); - } /* Free the private data */ if (dev->deleted) { @@ -179,33 +172,59 @@ 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 = { @@ -353,16 +372,19 @@ 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); return 0; }