linux-kernel - [PATCH v1 01/10] zram: avoid calling of zram_meta_free under init

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Date:	Wed, 21 Jan 2015 15:14:17 +0900
From:	Minchan Kim <minchan@...nel.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	Dan Streetman <ddstreet@...e.org>,
	Seth Jennings <sjennings@...iantweb.net>,
	Nitin Gupta <ngupta@...are.org>,
	Juneho Choi <juno.choi@....com>, Gunho Lee <gunho.lee@....com>,
	Luigi Semenzato <semenzato@...gle.com>,
	Jerome Marchand <jmarchan@...hat.com>,
	Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
	Minchan Kim <minchan@...nel.org>
Subject: [PATCH v1 01/10] zram: avoid calling of zram_meta_free under init_lock

We don't need to call zram_meta_free under init_lock.
What we need to prevent race is setting NULL into zram->meta
(ie, init_done). This patch does it.

Signed-off-by: Minchan Kim <minchan@...nel.org>
---
 drivers/block/zram/zram_drv.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 9250b3f..7e03d86 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -719,6 +719,8 @@ static void zram_reset_device(struct zram *zram, bool reset_capacity)
 	}
 
 	meta = zram->meta;
+	zram->meta = NULL;
+
 	/* Free all pages that are still in this zram device */
 	for (index = 0; index < zram->disksize >> PAGE_SHIFT; index++) {
 		unsigned long handle = meta->table[index].handle;
@@ -731,8 +733,6 @@ static void zram_reset_device(struct zram *zram, bool reset_capacity)
 	zcomp_destroy(zram->comp);
 	zram->max_comp_streams = 1;
 
-	zram_meta_free(zram->meta);
-	zram->meta = NULL;
 	/* Reset stats */
 	memset(&zram->stats, 0, sizeof(zram->stats));
 
@@ -741,6 +741,7 @@ static void zram_reset_device(struct zram *zram, bool reset_capacity)
 		set_capacity(zram->disk, 0);
 
 	up_write(&zram->init_lock);
+	zram_meta_free(meta);
 
 	/*
 	 * Revalidate disk out of the init_lock to avoid lockdep splat.
-- 
1.9.3

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