On 03/04/2014 11:10 AM, Sergey Senozhatsky wrote:
> While fixing lockdep spew of ->init_lock reported by Sasha Levin [1], Minchan
> Kim noted [2] that it's better to move compression backend allocation (using
> GPF_KERNEL) out of the ->init_lock lock, same way as with zram_meta_alloc(),
> in order to prevent the same lockdep spew.
>
> [1] https://lkml.org/lkml/2014/2/27/337
> [2] https://lkml.org/lkml/2014/3/3/32
>
> Cc: Sasha Levin <sasha.le...@oracle.com>
> Reported-by: Minchan Kim <minc...@kernel.org>
> Signed-off-by: Sergey Senozhatsky <sergey.senozhat...@gmail.com>
> ---
> drivers/block/zram/zram_drv.c | 27 +++++++++++++++------------
> 1 file changed, 15 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
> index 15d46f2..e4d536b 100644
> --- a/drivers/block/zram/zram_drv.c
> +++ b/drivers/block/zram/zram_drv.c
> @@ -580,9 +580,10 @@ static ssize_t disksize_store(struct device *dev,
> struct device_attribute *attr, const char *buf, size_t len)
> {
> u64 disksize;
> + struct zcomp *comp;
> struct zram_meta *meta;
> struct zram *zram = dev_to_zram(dev);
> - int err;
> + int err = -EINVAL;
>
> disksize = memparse(buf, NULL);
> if (!disksize)
> @@ -593,30 +594,32 @@ static ssize_t disksize_store(struct device *dev,
> if (!meta)
> return -ENOMEM;
>
> + comp = zcomp_create(zram->compressor, zram->max_comp_streams);
> + if (!comp) {
> + pr_info("Cannot initialise %s compressing backend\n",
> + zram->compressor);
> + goto out_cleanup;
> + }
> +
zcomp_create() could fail because of a failed allocation, in which case
ENOMEM would be more appropriate. I guess zcomp_create() should return
an errno in case of failure.
But that's an other problem than the one addressed in this patch:
Acked-by: Jerome Marchand <jmarc...@redhat.com>
> down_write(&zram->init_lock);
> if (init_done(zram)) {
> + up_write(&zram->init_lock);
> pr_info("Cannot change disksize for initialized device\n");
> err = -EBUSY;
> - goto out_free_meta;
> - }
> -
> - zram->comp = zcomp_create(zram->compressor, zram->max_comp_streams);
> - if (!zram->comp) {
> - pr_info("Cannot initialise %s compressing backend\n",
> - zram->compressor);
> - err = -EINVAL;
> - goto out_free_meta;
> + goto out_cleanup;
> }
>
> zram->meta = meta;
> + zram->comp = comp;
> zram->disksize = disksize;
> set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
> up_write(&zram->init_lock);
>
> return len;
>
> -out_free_meta:
> - up_write(&zram->init_lock);
> +out_cleanup:
> + if (comp)
> + zcomp_destroy(comp);
> zram_meta_free(meta);
> return err;
> }
>
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