2013-10-29 23:13:07

by Rashika Kheria

Subject: [PATCH v7 2/3] Staging: zram: Fix decrement of variable by calling bdput()

As suggested by Jerome Marchand "The code in reset_store get the block device
(bdget_disk()) but it does not put it (bdput()) when it's done using it.
The usage count is therefor incremented but never decremented."

Hence, this patch introduces a call to bdput() to decrement the variable after usage.

Cc: [email protected]
Signed-off-by: Rashika Kheria <[email protected]>
---

This revision fixes the following issues of the previous revision-
Handle more error cases

drivers/staging/zram/zram_drv.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c
index d640a8f..592e760 100644
--- a/drivers/staging/zram/zram_drv.c
+++ b/drivers/staging/zram/zram_drv.c
@@ -664,6 +664,9 @@ static ssize_t reset_store(struct device *dev,

/* Make sure all pending I/O is finished */
fsync_bdev(bdev);
+ bdput(bdev);
+ bdput(bdev->bd_holders);
+ bdput(do_reset);

zram_reset_device(zram, true);
return len;
--
1.7.9.5

2013-10-30 02:33:52

by Minchan Kim

Subject: Re: [PATCH v7 2/3] Staging: zram: Fix decrement of variable by calling bdput()

On Wed, Oct 30, 2013 at 04:42:56AM +0530, Rashika Kheria wrote:
> As suggested by Jerome Marchand "The code in reset_store get the block device
> (bdget_disk()) but it does not put it (bdput()) when it's done using it.
> The usage count is therefor incremented but never decremented."
>
> Hence, this patch introduces a call to bdput() to decrement the variable after usage.
>
> Cc: [email protected]
> Signed-off-by: Rashika Kheria <[email protected]>
> ---
>
> This revision fixes the following issues of the previous revision-
> Handle more error cases
>
> drivers/staging/zram/zram_drv.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c
> index d640a8f..592e760 100644
> --- a/drivers/staging/zram/zram_drv.c
> +++ b/drivers/staging/zram/zram_drv.c
> @@ -664,6 +664,9 @@ static ssize_t reset_store(struct device *dev,
>
> /* Make sure all pending I/O is finished */
> fsync_bdev(bdev);
> + bdput(bdev);
> + bdput(bdev->bd_holders);
> + bdput(do_reset);

I meant it.

diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c
index e77fb6e..32f9a44 100644
--- a/drivers/staging/zram/zram_drv.c
+++ b/drivers/staging/zram/zram_drv.c
@@ -621,22 +621,30 @@ static ssize_t reset_store(struct device *dev,
bdev = bdget_disk(zram->disk, 0);

/* Do not reset an active device! */
- if (bdev->bd_holders)
- return -EBUSY;
+ if (bdev->bd_holders) {
+ ret = -EBUSY;
+ goto out;
+ }

ret = kstrtou16(buf, 10, &do_reset);
if (ret)
- return ret;
+ goto out;

- if (!do_reset)
- return -EINVAL;
+ if (!do_reset) {
+ ret = -EINVAL;
+ goto out;
+ }

/* Make sure all pending I/O is finished */
- if (bdev)
- fsync_bdev(bdev);
+ fsync_bdev(bdev);
+ bdput(bdev);

zram_reset_device(zram);
return len;
+
+out:
+ bdput(bdev);
+ return ret;
}

static void __zram_make_request(struct zram *zram, struct bio *bio, int rw)

--
Kind regards,
Minchan Kim