On (09/06/13 16:42), Jerome Marchand wrote:
> On 09/06/2013 03:47 PM, Sergey Senozhatsky wrote:
> > Calling handle_pending_slot_free() for every RW operation may
> > cause unneccessary slot_free_lock locking, because most likely
> > process will see NULL slot_free_rq. handle_pending_slot_free()
> > only when current detects that slot_free_rq is not NULL.
> >
> > Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
> >
> > ---
> >
> > drivers/staging/zram/zram_drv.c | 5 +++--
> > 1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c
> > index 91d94b5..17386e2 100644
> > --- a/drivers/staging/zram/zram_drv.c
> > +++ b/drivers/staging/zram/zram_drv.c
> > @@ -532,14 +532,15 @@ static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
> > {
> > int ret;
> >
> > + if (zram->slot_free_rq)
> > + handle_pending_slot_free(zram);
> > +
>
> Calling handle_pending_slot_free() without holding zram->lock?
> That's racy.
sorry, my bad. it should take down_write() lock.
-ss
> Jerome
>
> > if (rw == READ) {
> > down_read(&zram->lock);
> > - handle_pending_slot_free(zram);
> > ret = zram_bvec_read(zram, bvec, index, offset, bio);
> > up_read(&zram->lock);
> > } else {
> > down_write(&zram->lock);
> > - handle_pending_slot_free(zram);
> > ret = zram_bvec_write(zram, bvec, index, offset);
> > up_write(&zram->lock);
> > }
> >
> > --
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> >
>
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