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.
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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