staging: 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@gmail.com>
Acked-by: Jerome Marchand <jmarchand@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 644d478793c6594277f8ae76954da4ace7ac6f96)
Signed-off-by: Alex Shi <alex.shi@linaro.org>

diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c
index 753877431b5f45174066276346b4d8c737137541..c549e3940bcf3f57acff52f5656d780bceb6dafe 100644 (file)
--- 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)