Messages in this thread Patch in this message | | | From | Maxim Levitsky <> | Subject | [PATCH 05/17] blktrans: add proper locking | Date | Tue, 9 Feb 2010 18:57:33 +0200 |
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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 <maximlevitsky@gmail.com> --- 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; } -- 1.6.3.3
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