mtd: blktrans: Hotplug fixes

* Add locking where it was missing.

* Don't do a get_mtd_device in blktrans_open because it would lead to a
  deadlock; instead do that in add_mtd_blktrans_dev.

* Only free the mtd_blktrans_dev structure when the last user exits.

* Flush request queue on device removal.

* Track users, and call tr->release in del_mtd_blktrans_dev
  Due to that ->open and release aren't called more that once.

Now it is safe to call del_mtd_blktrans_dev while the device is still in use.

Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

diff --git a/drivers/mtd/ftl.c b/drivers/mtd/ftl.c
index e56d6b4..62da9eb 100644 (file)
--- a/drivers/mtd/ftl.c
+++ b/drivers/mtd/ftl.c
@@ -1082,7 +1082,6 @@ static void ftl_remove_dev(struct mtd_blktrans_dev *dev)
 {
        del_mtd_blktrans_dev(dev);
        ftl_freepart((partition_t *)dev);
-       kfree(dev);
 }
 
 static struct mtd_blktrans_ops ftl_tr = {

diff --git a/drivers/mtd/inftlcore.c b/drivers/mtd/inftlcore.c
index 8aca552..015a7fe 100755 (executable)
--- a/drivers/mtd/inftlcore.c
+++ b/drivers/mtd/inftlcore.c
@@ -139,7 +139,6 @@ static void inftl_remove_dev(struct mtd_blktrans_dev *dev)
 
        kfree(inftl->PUtable);
        kfree(inftl->VUtable);
-       kfree(inftl);
 }
 
 /*

diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c
index 6a57262..646cc84 100644 (file)
--- a/drivers/mtd/mtd_blkdevs.c
+++ b/drivers/mtd/mtd_blkdevs.c
@@ -24,6 +24,40 @@
 #include "mtdcore.h"
 
 static LIST_HEAD(blktrans_majors);
+static DEFINE_MUTEX(blktrans_ref_mutex);
+
+void blktrans_dev_release(struct kref *kref)
+{
+       struct mtd_blktrans_dev *dev =
+               container_of(kref, struct mtd_blktrans_dev, ref);
+
+       dev->disk->private_data = NULL;
+       put_disk(dev->disk);
+       list_del(&dev->list);
+       kfree(dev);
+}
+
+static struct mtd_blktrans_dev *blktrans_dev_get(struct gendisk *disk)
+{
+       struct mtd_blktrans_dev *dev;
+
+       mutex_lock(&blktrans_ref_mutex);
+       dev = disk->private_data;
+
+       if (!dev)
+               goto unlock;
+       kref_get(&dev->ref);
+unlock:
+       mutex_unlock(&blktrans_ref_mutex);
+       return dev;
+}
+
+void blktrans_dev_put(struct mtd_blktrans_dev *dev)
+{
+       mutex_lock(&blktrans_ref_mutex);
+       kref_put(&dev->ref, blktrans_dev_release);
+       mutex_unlock(&blktrans_ref_mutex);
+}
 
 
 static int do_blktrans_request(struct mtd_blktrans_ops *tr,
@@ -111,81 +145,112 @@ static int mtd_blktrans_thread(void *arg)
 
 static void mtd_blktrans_request(struct request_queue *rq)
 {
-       struct mtd_blktrans_dev *dev = rq->queuedata;
-       wake_up_process(dev->thread);
-}
+       struct mtd_blktrans_dev *dev;
+       struct request *req = NULL;
+
+       dev = rq->queuedata;
 
+       if (!dev)
+               while ((req = blk_fetch_request(rq)) != NULL)
+                       __blk_end_request_all(req, -ENODEV);
+       else
+               wake_up_process(dev->thread);
+}
 
 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;
-
-       if (!try_module_get(tr->owner))
-               goto out_tr;
-
-       /* 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);
+       struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
+       int ret;
+
+       if (!dev)
+               return -ERESTARTSYS;
+
+       mutex_lock(&dev->lock);
+
+       if (!dev->mtd) {
+               ret = -ENXIO;
+               goto unlock;
        }
- out:
+
+       ret = !dev->open++ && dev->tr->open ? dev->tr->open(dev) : 0;
+
+       /* Take another reference on the device so it won't go away till
+               last release */
+       if (!ret)
+               kref_get(&dev->ref);
+unlock:
+       mutex_unlock(&dev->lock);
+       blktrans_dev_put(dev);
        return ret;
 }
 
 static int blktrans_release(struct gendisk *disk, fmode_t mode)
 {
-       struct mtd_blktrans_dev *dev = disk->private_data;
-       struct mtd_blktrans_ops *tr = dev->tr;
-       int ret = 0;
+       struct mtd_blktrans_dev *dev = blktrans_dev_get(disk);
+       int ret = -ENXIO;
 
-       if (tr->release)
-               ret = tr->release(dev);
+       if (!dev)
+               return ret;
 
-       if (!ret) {
-               dev->mtd->usecount--;
-               put_mtd_device(dev->mtd);
-               module_put(tr->owner);
-       }
+       mutex_lock(&dev->lock);
+
+       /* Release one reference, we sure its not the last one here*/
+       kref_put(&dev->ref, blktrans_dev_release);
 
+       if (!dev->mtd)
+               goto unlock;
+
+       ret = !--dev->open && dev->tr->release ? dev->tr->release(dev) : 0;
+unlock:
+       mutex_unlock(&dev->lock);
+       blktrans_dev_put(dev);
        return ret;
 }
 
 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 {
-       struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
+       struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
+       int ret = -ENXIO;
+
+       if (!dev)
+               return ret;
+
+       mutex_lock(&dev->lock);
 
-       if (dev->tr->getgeo)
-               return dev->tr->getgeo(dev, geo);
-       return -ENOTTY;
+       if (!dev->mtd)
+               goto unlock;
+
+       ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : 0;
+unlock:
+       mutex_unlock(&dev->lock);
+       blktrans_dev_put(dev);
+       return ret;
 }
 
 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;
+       struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
+       int ret = -ENXIO;
+
+       if (!dev)
+               return ret;
+
+       mutex_lock(&dev->lock);
+
+       if (!dev->mtd)
+               goto unlock;
 
        switch (cmd) {
        case BLKFLSBUF:
-               if (tr->flush)
-                       return tr->flush(dev);
-               /* The core code did the work, we had nothing to do. */
-               return 0;
+               ret = dev->tr->flush ? dev->tr->flush(dev) : 0;
        default:
-               return -ENOTTY;
+               ret = -ENOTTY;
        }
+unlock:
+       mutex_unlock(&dev->lock);
+       blktrans_dev_put(dev);
+       return ret;
 }
 
 static const struct block_device_operations mtd_blktrans_ops = {
@@ -209,6 +274,7 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
                BUG();
        }
 
+       mutex_lock(&blktrans_ref_mutex);
        list_for_each_entry(d, &tr->devs, list) {
                if (new->devnum == -1) {
                        /* Use first free number */
@@ -220,6 +286,7 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
                        }
                } else if (d->devnum == new->devnum) {
                        /* Required number taken */
+                       mutex_unlock(&blktrans_ref_mutex);
                        return -EBUSY;
                } else if (d->devnum > new->devnum) {
                        /* Required number was free */
@@ -237,16 +304,20 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
         * minor numbers and that the disk naming code below can cope
         * with this number. */
        if (new->devnum > (MINORMASK >> tr->part_bits) ||
-           (tr->part_bits && new->devnum >= 27 * 26))
+           (tr->part_bits && new->devnum >= 27 * 26)) {
+               mutex_unlock(&blktrans_ref_mutex);
                goto error1;
+       }
 
        list_add_tail(&new->list, &tr->devs);
  added:
+       mutex_unlock(&blktrans_ref_mutex);
+
        mutex_init(&new->lock);
+       kref_init(&new->ref);
        if (!tr->writesect)
                new->readonly = 1;
 
-
        /* Create gendisk */
        ret = -ENOMEM;
        gd = alloc_disk(1 << tr->part_bits);
@@ -275,7 +346,6 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 
        set_capacity(gd, (new->size * tr->blksize) >> 9);
 
-
        /* Create the request queue */
        spin_lock_init(&new->queue_lock);
        new->rq = blk_init_queue(mtd_blktrans_request, &new->queue_lock);
@@ -292,6 +362,9 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 
        gd->queue = new->rq;
 
+       __get_mtd_device(new->mtd);
+       __module_get(tr->owner);
+
        /* Create processing thread */
        /* TODO: workqueue ? */
        new->thread = kthread_run(mtd_blktrans_thread, new,
@@ -308,6 +381,8 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
        add_disk(gd);
        return 0;
 error4:
+       module_put(tr->owner);
+       __put_mtd_device(new->mtd);
        blk_cleanup_queue(new->rq);
 error3:
        put_disk(new->disk);
@@ -320,20 +395,41 @@ error1:
 
 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 {
+       unsigned long flags;
+
        if (mutex_trylock(&mtd_table_mutex)) {
                mutex_unlock(&mtd_table_mutex);
                BUG();
        }
 
-       list_del(&old->list);
-
-       /* stop new requests to arrive */
+       /* Stop new requests to arrive */
        del_gendisk(old->disk);
 
        /* Stop the thread */
        kthread_stop(old->thread);
 
+       /* Kill current requests */
+       spin_lock_irqsave(&old->queue_lock, flags);
+       old->rq->queuedata = NULL;
+       blk_start_queue(old->rq);
+       spin_unlock_irqrestore(&old->queue_lock, flags);
        blk_cleanup_queue(old->rq);
+
+       /* Ask trans driver for release to the mtd device */
+       mutex_lock(&old->lock);
+       if (old->open && old->tr->release) {
+               old->tr->release(old);
+               old->open = 0;
+       }
+
+       __put_mtd_device(old->mtd);
+       module_put(old->tr->owner);
+
+       /* At that point, we don't touch the mtd anymore */
+       old->mtd = NULL;
+
+       mutex_unlock(&old->lock);
+       blktrans_dev_put(old);
        return 0;
 }
 
@@ -396,7 +492,6 @@ int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
                        tr->add_mtd(tr, mtd);
 
        mutex_unlock(&mtd_table_mutex);
-
        return 0;
 }
 
@@ -406,7 +501,6 @@ int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
 
        mutex_lock(&mtd_table_mutex);
 
-
        /* Remove it from the list of active majors */
        list_del(&tr->list);
 

diff --git a/drivers/mtd/mtdblock.c b/drivers/mtd/mtdblock.c
index 69f6bf2..8e5da1e 100644 (file)
--- a/drivers/mtd/mtdblock.c
+++ b/drivers/mtd/mtdblock.c
@@ -354,9 +354,7 @@ static void mtdblock_add_mtd(struct mtd_blktrans_ops *tr, struct mtd_info *mtd)
 static void mtdblock_remove_dev(struct mtd_blktrans_dev *dev)
 {
        struct mtdblk_dev *mtdblk = container_of(dev, struct mtdblk_dev, mbd);
-
        del_mtd_blktrans_dev(dev);
-       kfree(mtdblk);
 }
 
 static struct mtd_blktrans_ops mtdblock_tr = {

diff --git a/drivers/mtd/mtdblock_ro.c b/drivers/mtd/mtdblock_ro.c
index 852165f..54ff288 100644 (file)
--- a/drivers/mtd/mtdblock_ro.c
+++ b/drivers/mtd/mtdblock_ro.c
@@ -49,7 +49,6 @@ static void mtdblock_add_mtd(struct mtd_blktrans_ops *tr, struct mtd_info *mtd)
 static void mtdblock_remove_dev(struct mtd_blktrans_dev *dev)
 {
        del_mtd_blktrans_dev(dev);
-       kfree(dev);
 }
 
 static struct mtd_blktrans_ops mtdblock_tr = {

diff --git a/drivers/mtd/nftlcore.c b/drivers/mtd/nftlcore.c
index 1002e18..a4578bf 100644 (file)
--- a/drivers/mtd/nftlcore.c
+++ b/drivers/mtd/nftlcore.c
@@ -126,7 +126,6 @@ static void nftl_remove_dev(struct mtd_blktrans_dev *dev)
        del_mtd_blktrans_dev(dev);
        kfree(nftl->ReplUnitTable);
        kfree(nftl->EUNtable);
-       kfree(nftl);
 }
 
 /*

diff --git a/drivers/mtd/rfd_ftl.c b/drivers/mtd/rfd_ftl.c
index d2aa9c4..63b83c0 100644 (file)
--- a/drivers/mtd/rfd_ftl.c
+++ b/drivers/mtd/rfd_ftl.c
@@ -817,7 +817,6 @@ static void rfd_ftl_remove_dev(struct mtd_blktrans_dev *dev)
        vfree(part->sector_map);
        kfree(part->header_cache);
        kfree(part->blocks);
-       kfree(part);
 }
 
 static struct mtd_blktrans_ops rfd_ftl_tr = {

diff --git a/drivers/mtd/ssfdc.c b/drivers/mtd/ssfdc.c
index 3f67e00..81c4ecd 100644 (file)
--- a/drivers/mtd/ssfdc.c
+++ b/drivers/mtd/ssfdc.c
@@ -375,7 +375,6 @@ static void ssfdcr_remove_dev(struct mtd_blktrans_dev *dev)
 
        del_mtd_blktrans_dev(dev);
        kfree(ssfdc->logic_block_map);
-       kfree(ssfdc);
 }
 
 static int ssfdcr_readsect(struct mtd_blktrans_dev *dev,

diff --git a/include/linux/mtd/blktrans.h b/include/linux/mtd/blktrans.h
index a4b3928..d89b8fb 100644 (file)
--- a/include/linux/mtd/blktrans.h
+++ b/include/linux/mtd/blktrans.h
@@ -9,6 +9,7 @@
 #define __MTD_TRANS_H__
 
 #include <linux/mutex.h>
+#include <linux/kref.h>
 
 struct hd_geometry;
 struct mtd_info;
@@ -24,6 +25,8 @@ struct mtd_blktrans_dev {
        int devnum;
        unsigned long size;
        int readonly;
+       int open;
+       struct kref ref;
        struct gendisk *disk;
        struct task_struct *thread;
        struct request_queue *rq;