On Thu, Aug 23 2018 at 6:12pm -0400, Damien Le Moal <[email protected]> wrote:
> John, > > On 2018/08/23 10:37, John Pittman wrote: > > The API surrounding refcount_t should be used in place of atomic_t > > when variables are being used as reference counters. This API can > > prevent issues such as counter overflows and use-after-free > > conditions. Within the dm zoned metadata stack, the atomic_t API > > is used for mblk->ref and zone->refcount. Change these to use > > refcount_t, avoiding the issues mentioned. > > > > Signed-off-by: John Pittman <[email protected]> > > --- > > drivers/md/dm-zoned-metadata.c | 25 +++++++++++++------------ > > drivers/md/dm-zoned.h | 2 +- > > 2 files changed, 14 insertions(+), 13 deletions(-) > > > > diff --git a/drivers/md/dm-zoned-metadata.c b/drivers/md/dm-zoned-metadata.c > > index 969954915566..92e635749414 100644 > > --- a/drivers/md/dm-zoned-metadata.c > > +++ b/drivers/md/dm-zoned-metadata.c > > @@ -99,7 +99,7 @@ struct dmz_mblock { > > struct rb_node node; > > struct list_head link; > > sector_t no; > > - atomic_t ref; > > + refcount_t ref; > > While reviewing your patch, I realized that this ref is always manipulated > under > the zmd->mblk_lock spinlock. So there is no need for it to be an atomic or a > refcount. An unsigned int would do as well and be faster. My fault. > > I will send a patch to go on top of yours to fix that. Hi Damien, Given what you've said I'm not seeing the point in the intermediate refcount_t conversion. I'd rather you just send a patch that switches atomic_t to int. Thanks, Mike -- dm-devel mailing list [email protected] https://www.redhat.com/mailman/listinfo/dm-devel
