linux-kernel - [PATCH staging-next] zram: protect zram_reset

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Message-ID: <20130626122839.GA2268@swordfish.minsk.epam.com>
Date:	Wed, 26 Jun 2013 15:28:39 +0300
From:	Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	Nitin Gupta <ngupta@...are.org>, linux-kernel@...r.kernel.org
Subject: [PATCH staging-next] zram: protect zram_reset_device() call

Commit 9b3bb7abcdf2df0f1b2657e6cbc9d06bc2b3b36f (remove
zram_sysfs file (v2)) accidentally made zram_reset_device()
racy. Protect zram_reset_device() call with zram->lock.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>

---
 drivers/staging/zram/zram_drv.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c
index 82c7202..e77fb6e 100644
--- a/drivers/staging/zram/zram_drv.c
+++ b/drivers/staging/zram/zram_drv.c
@@ -527,8 +527,11 @@ static void zram_reset_device(struct zram *zram)
 	size_t index;
 	struct zram_meta *meta;
 
-	if (!zram->init_done)
+	down_write(&zram->init_lock);
+	if (!zram->init_done) {
+		up_write(&zram->init_lock);
 		return;
+	}
 
 	meta = zram->meta;
 	zram->init_done = 0;
@@ -549,6 +552,7 @@ static void zram_reset_device(struct zram *zram)
 
 	zram->disksize = 0;
 	set_capacity(zram->disk, 0);
+	up_write(&zram->init_lock);
 }
 
 static void zram_init_device(struct zram *zram, struct zram_meta *meta)

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