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

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Message-ID: <20131030023356.GB17013@bbox>
Date:	Wed, 30 Oct 2013 11:33:56 +0900
From:	Minchan Kim <minchan@...nel.org>
To:	Rashika Kheria <rashika.kheria@...il.com>
Cc:	opw-kernel@...glegroups.com,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiang Liu <jiang.liu@...wei.com>,
	Nitin Gupta <ngupta@...are.org>,
	Jerome Marchand <jmarchand@...hat.com>,
	linux-kernel@...r.kernel.org, stable@...r.kernel.org
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: stable@...r.kernel.org
> Signed-off-by: Rashika Kheria <rashika.kheria@...il.com>
> ---
> 
> 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
--
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