Patchwork [03/17] blktrans: track open and close calls.

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Submitter Maxim Levitsky
Date Jan. 30, 2010, 3:02 p.m.
Message ID <1264863768-27606-4-git-send-email-maximlevitsky@gmail.com>
Download mbox | patch
Permalink /patch/44072/
State New
Headers show

Comments

Maxim Levitsky - Jan. 30, 2010, 3:02 p.m.
This patch adds tracking for open and close calls.
Now trans ->open and ->release are never called twise in a row
->release is also called once before mtd device disappers

Proper locking will be added in follow up patch

Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com>
---
 drivers/mtd/mtd_blkdevs.c    |   18 ++++++++++++++++++
 include/linux/mtd/blktrans.h |    1 +
 2 files changed, 19 insertions(+), 0 deletions(-)
Ricard Wanderlof - Feb. 1, 2010, 7:46 a.m.
On Sat, 30 Jan 2010, Maxim Levitsky wrote:

> This patch adds tracking for open and close calls.
> Now trans ->open and ->release are never called twise in a row
> ->release is also called once before mtd device disappers
> ...

> --- a/drivers/mtd/mtd_blkdevs.c
> +++ b/drivers/mtd/mtd_blkdevs.c
> @@ -128,6 +128,9 @@ static int blktrans_open(struct block_device *bdev, fmode_t mode)
> 	if (!get_mtd_device(NULL, dev->mtd->index))
> 		goto out;
>
> +	if (dev->open++)
> +		goto out;
> +
> 	if (!try_module_get(tr->owner))
> 		goto out_tr;
>
> @@ -153,6 +156,10 @@ static int blktrans_release(struct gendisk *disk, fmode_t mode)
> 	struct mtd_blktrans_ops *tr = dev->tr;
> 	int ret = 0;
>
> +	dev->open--;
> +	if (dev->open)
> +		return 0;
> +

Just a very minor quibble: if you use if (dev->open++) in one function, 
why not use if (--dev->open) in the other? Or separate the 
increment/decrement from the test, depending on you style preferences.

/Ricard
Maxim Levitsky - Feb. 1, 2010, 3:40 p.m.
On Mon, 2010-02-01 at 08:46 +0100, Ricard Wanderlof wrote: 
> On Sat, 30 Jan 2010, Maxim Levitsky wrote:
> 
> > This patch adds tracking for open and close calls.
> > Now trans ->open and ->release are never called twise in a row
> > ->release is also called once before mtd device disappers
> > ...
> 
> > --- a/drivers/mtd/mtd_blkdevs.c
> > +++ b/drivers/mtd/mtd_blkdevs.c
> > @@ -128,6 +128,9 @@ static int blktrans_open(struct block_device *bdev, fmode_t mode)
> > 	if (!get_mtd_device(NULL, dev->mtd->index))
> > 		goto out;
> >
> > +	if (dev->open++)
> > +		goto out;
> > +
> > 	if (!try_module_get(tr->owner))
> > 		goto out_tr;
> >
> > @@ -153,6 +156,10 @@ static int blktrans_release(struct gendisk *disk, fmode_t mode)
> > 	struct mtd_blktrans_ops *tr = dev->tr;
> > 	int ret = 0;
> >
> > +	dev->open--;
> > +	if (dev->open)
> > +		return 0;
> > +
> 
> Just a very minor quibble: if you use if (dev->open++) in one function, 
> why not use if (--dev->open) in the other? Or separate the 
> increment/decrement from the test, depending on you style preferences.
No problem, this just got lost in all the noise.
I tried all kinds of approaches to make hotplug reliable, before finally
making it be so. (It is really stable here, I didn't have any hotplug
related issues for very long time)

In fact I feel that my xd card is more stable that sd one...
(I recently found a bug in sdhci driver....)

I would be very happy to receive a full review of the patches, and get
it in the kernel.

Best regards,
Maxim Levitsky

Patch

diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c
index 93c87af..966398b 100644
--- a/drivers/mtd/mtd_blkdevs.c
+++ b/drivers/mtd/mtd_blkdevs.c
@@ -128,6 +128,9 @@  static int blktrans_open(struct block_device *bdev, fmode_t mode)
 	if (!get_mtd_device(NULL, dev->mtd->index))
 		goto out;
 
+	if (dev->open++)
+		goto out;
+
 	if (!try_module_get(tr->owner))
 		goto out_tr;
 
@@ -153,6 +156,10 @@  static int blktrans_release(struct gendisk *disk, fmode_t mode)
 	struct mtd_blktrans_ops *tr = dev->tr;
 	int ret = 0;
 
+	dev->open--;
+	if (dev->open)
+		return 0;
+
 	if (tr->release)
 		ret = tr->release(dev);
 
@@ -304,6 +311,7 @@  int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 	if (new->readonly)
 		set_disk_ro(gd, 1);
 
+	new->open = 0;
 	add_disk(gd);
 
 	return 0;
@@ -333,6 +341,16 @@  int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 	/* Stop the thread */
 	kthread_stop(old->thread);
 
+	if (old->open) {
+		if (old->tr->release)
+			old->tr->release(old);
+		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;
+ 
 	blk_cleanup_queue(old->rq);
 	return 0;
 }
diff --git a/include/linux/mtd/blktrans.h b/include/linux/mtd/blktrans.h
index a4b3928..507f7b2 100644
--- a/include/linux/mtd/blktrans.h
+++ b/include/linux/mtd/blktrans.h
@@ -24,6 +24,7 @@  struct mtd_blktrans_dev {
 	int devnum;
 	unsigned long size;
 	int readonly;
+	int open;
 	struct gendisk *disk;
 	struct task_struct *thread;
 	struct request_queue *rq;