Re: [dpdk-dev] [PATCH] __rte_hash_add_key_with_hash not releasing multiwriter_lock in failure paths

["De Lara Guarch, Pablo" <pablo.de.lara.guarch@intel.com>]

> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of De Lara Guarch,
> Pablo
> Sent: Wednesday, July 5, 2017 3:51 PM
> To: mstolarchuk <mike.stolarchuk@bigswitch.com>; Richardson, Bruce
> <bruce.richardson@intel.com>
> Cc: dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH] __rte_hash_add_key_with_hash not
> releasing multiwriter_lock in failure paths
> 
> 
> 
> > -----Original Message-----
> > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of mstolarchuk
> > Sent: Friday, May 26, 2017 1:31 PM
> > To: bruce.richardson@intel.co
> > Cc: dev@dpdk.org
> > Subject: [dpdk-dev] [PATCH] __rte_hash_add_key_with_hash not
> releasing
> > multiwriter_lock in failure paths
> >
> > Signed-off-by: mstolarchuk <mike.stolarchuk@bigswitch.com>
> > ---
> >  lib/librte_hash/rte_cuckoo_hash.c | 13 +++++++++----
> >  1 file changed, 9 insertions(+), 4 deletions(-)
> >
> > diff --git a/lib/librte_hash/rte_cuckoo_hash.c
> > b/lib/librte_hash/rte_cuckoo_hash.c
> > index 645c0cf..37a8110 100644
> > --- a/lib/librte_hash/rte_cuckoo_hash.c
> > +++ b/lib/librte_hash/rte_cuckoo_hash.c
> > @@ -538,8 +538,10 @@ struct rte_hash *
> >  			n_slots = rte_ring_mc_dequeue_burst(h-
> > >free_slots,
> >  					cached_free_slots->objs,
> >  					LCORE_CACHE_SIZE, NULL);
> > -			if (n_slots == 0)
> > -				return -ENOSPC;
> > +			if (n_slots == 0) {
> > +				ret = -ENOSPC;
> > +				goto failure;
> > +			}
> >
> >  			cached_free_slots->len += n_slots;
> >  		}
> > @@ -548,8 +550,10 @@ struct rte_hash *
> >  		cached_free_slots->len--;
> >  		slot_id = cached_free_slots->objs[cached_free_slots->len];
> >  	} else {
> > -		if (rte_ring_sc_dequeue(h->free_slots, &slot_id) != 0)
> > -			return -ENOSPC;
> > +		if (rte_ring_sc_dequeue(h->free_slots, &slot_id) != 0) {
> > +			ret = -ENOSPC;
> > +			goto failure;
> > +		}
> >  	}
> >
> >  	new_k = RTE_PTR_ADD(keys, (uintptr_t)slot_id * h-
> > >key_entry_size); @@ -659,6 +663,7 @@ struct rte_hash *
> >  	/* Error in addition, store new slot back in the ring and return
> > error */
> >  	enqueue_slot_back(h, cached_free_slots, (void *)((uintptr_t)
> > new_idx));
> >
> > +failure:
> >  	if (h->add_key == ADD_KEY_MULTIWRITER)
> >  		rte_spinlock_unlock(h->multiwriter_lock);
> >  	return ret;
> > --
> > 1.9.1
> 
> Hi  Mike,
> 
> Thanks for the patch, it looks correct to me.
> The code is fine, but the commit message needs some rework.
> Title should start with: "hash: ...", since this is aiming the hash library, So
> the title could be: "hash: fix lock release on add"
> 
> Then, some explanation on what the fix is doing would be good.
> 
> Lastly, since this is a fix, it requires a fixes line and CC to the stable branch:
> 
> Fixes: be856325cba3 ("hash: add scalable multi-writer insertion with Intel
> TSX")
> CC: stable@dpdk.org

FYI, I just submitted a v2 with the commit fixed for you, as you might not be available
these days and the RC1 will be created soon.

Pablo
> 
> Thanks,
> Pablo