[PATCH 1/2] zram: free meta out of init_lock

Minchan Kim
2015-01-23T05:58:43Z

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

Signed-off-by: Minchan Kim <minchan@kernel.org>
---
drivers/block/zram/zram_drv.c | 28 ++++++++++++++++------------
1 file changed, 16 insertions(+), 12 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 9250b3f54a8f..0299d82275e7 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -708,6 +708,7 @@ static void zram_reset_device(struct zram *zram, bool reset_capacity)
{
size_t index;
struct zram_meta *meta;
+ struct zcomp *comp;

down_write(&zram->init_lock);

@@ -719,20 +720,10 @@ static void zram_reset_device(struct zram *zram, bool reset_capacity)
}

meta = zram->meta;
- /* 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;
- if (!handle)
- continue;
-
- zs_free(meta->mem_pool, handle);
- }
-
- zcomp_destroy(zram->comp);
+ comp = zram->comp;
+ zram->meta = NULL;
zram->max_comp_streams = 1;

- zram_meta_free(zram->meta);
- zram->meta = NULL;
/* Reset stats */
memset(&zram->stats, 0, sizeof(zram->stats));

@@ -742,6 +733,19 @@ static void zram_reset_device(struct zram *zram, bool reset_capacity)

up_write(&zram->init_lock);

+ /* 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;
+
+ if (!handle)
+ continue;
+
+ zs_free(meta->mem_pool, handle);
+ }
+
+ zcomp_destroy(comp);
+ zram_meta_free(meta);
+
/*
* Revalidate disk out of the init_lock to avoid lockdep splat.
* It's okay because disk's capacity is protected by init_lock
--
1.9.1