On (03/05/14 15:57), Jerome Marchand wrote:
> 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 <[email protected]>
> > Reported-by: Minchan Kim <[email protected]>
> > Signed-off-by: Sergey Senozhatsky <[email protected]>
> > ---
> > 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:
>
There are two possible cases of failed zcomp_create(). One is,
you're right, -ENOMEM. The second one is request of unsupported
compression algorithm - -EINVAL. agree, it makes sense to return
ERR_PTR() from zcomp_create(): -EINVAL or -ENOMEM.
-ss
> Acked-by: Jerome Marchand <[email protected]>
>
> > 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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