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From: Olivier Matz <olivier.matz@6wind.com>
To: John Daley <johndale@cisco.com>, dev@dpdk.org
Cc: bruce.richardson@intel.com
Subject: Re: [dpdk-dev] [PATCH] net/enic: decrement Tx mbuf reference count before recycling
Date: Mon, 11 Jul 2016 12:04:17 +0200	[thread overview]
Message-ID: <1ca338a4-a8fe-8149-2373-d02fee3199cb@6wind.com> (raw)
In-Reply-To: <1468016521-20280-1-git-send-email-johndale@cisco.com>

Hi John,

On 07/09/2016 12:22 AM, John Daley wrote:
> In the Tx cleanup function, the reference count in mbufs to be
> returned to the pool should to be decremented before they are
> returned. Decrementing is not done by rte_mempool_put_bulk()
> so it must be done separately using __rte_pktmbuf_prefree_seg().
> If decrementing does not result in a 0 reference count the mbuf
> is not returned to the pool and whatever has the last reference
> is responsible for freeing.
> 
> Fixes: 36935afbc53c ("net/enic: refactor Tx mbuf recycling")
> Reviewed-by: Nelson Escobar <neescoba@cisco.com>
> Signed-off-by: John Daley <johndale@cisco.com>
> ---
> Since reference counts are set to 0 when mbufs are reallocated from the
> pool, and sending packets with reference count not equal to 1 is probably
> an application error, this patch may not be critical. But a debug ASSERT
> caught it and it would be nice to have it fixed in 16.07.

Sending a packet with refcnt != 1 is not an error. It can happen when
using mbuf clones. So indeed it would be better to have in 16.07.

For the same reason, I also wonder if enic_free_wq_buf() should also be
updated with:

-       rte_mempool_put(mbuf->pool, mbuf);
+       rte_pktmbuf_free(mbuf);


Regards,
Olivier

  parent reply	other threads:[~2016-07-11 10:04 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-07-08 22:22 John Daley
2016-07-08 22:22 ` [dpdk-dev] [PATCH] net/enic: increment filter failure counter John Daley
2016-07-15 21:26   ` Thomas Monjalon
2016-07-11 10:04 ` Olivier Matz [this message]
2016-07-11 19:41   ` [dpdk-dev] [PATCH] net/enic: decrement Tx mbuf reference count before recycling John Daley (johndale)
2016-07-11 19:45   ` [dpdk-dev] [PATCH v2] " John Daley
2016-07-15 21:27     ` Thomas Monjalon

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