[dpdk-dev] [PATCH dpdk-dev v3] mempool: sort the rte_mempool_ops by name

[Jerin Jacob]

On Fri, Mar 6, 2020 at 7:06 PM <xiangxia.m.yue at gmail.com> wrote:
>
> From: Tonghao Zhang <xiangxia.m.yue at gmail.com>
>
> The order of mempool initiation affects mempool index in the
> rte_mempool_ops_table. For example, when building APPs with:
>
> $ gcc -lrte_mempool_bucket -lrte_mempool_ring ...
>
> The "bucket" mempool will be registered firstly, and its index
> in table is 0 while the index of "ring" mempool is 1. DPDK
> uses the mk/rte.app.mk to build APPs, and others, for example,
> Open vSwitch, use the libdpdk.a or libdpdk.so to build it.
> The mempool lib linked in dpdk and Open vSwitch is different.
>
> The mempool can be used between primary and secondary process,
> such as dpdk-pdump and pdump-pmd/Open vSwitch(pdump enabled).
> There will be a crash because dpdk-pdump creates the "ring_mp_mc"
> ring which index in table is 0, but the index of "bucket" ring
> is 0 in Open vSwitch. If Open vSwitch use the index 0 to get
> mempool ops and malloc memory from mempool. The crash will occur:
>
>     bucket_dequeue (access null and crash)
>     rte_mempool_get_ops (should get "ring_mp_mc",
>                          but get "bucket" mempool)
>     rte_mempool_ops_dequeue_bulk
>     ...
>     rte_pktmbuf_alloc
>     rte_pktmbuf_copy
>     pdump_copy
>     pdump_rx
>     rte_eth_rx_burst
>
> To avoid the crash, there are some solution:
> * constructor priority: Different mempool uses different
>   priority in RTE_INIT, but it's not easy to maintain.
>
> * change mk/rte.app.mk: Change the order in mk/rte.app.mk to
>   be same as libdpdk.a/libdpdk.so, but when adding a new mempool
>   driver in future, we must make sure the order.
>
> * register mempool orderly: Sort the mempool when registering,
>   so the lib linked will not affect the index in mempool table.
>
> Signed-off-by: Tonghao Zhang <xiangxia.m.yue at gmail.com>
> Acked-by: Olivier Matz <olivier.matz at 6wind.com>

Acked-by: Jerin Jacob <jerinj at marvell.com>


> ---
> v3:
> * fix checkpatches.sh WARNING
> * change "initiation -> initialization"
>
> v2:
> * use the qsort to sort the mempool_ops.
> * tested: https://travis-ci.com/ovn-open-virtual-networks/dpdk-next-net/builds/151894026
> ---
>  lib/librte_mempool/rte_mempool_ops.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
>
> diff --git a/lib/librte_mempool/rte_mempool_ops.c b/lib/librte_mempool/rte_mempool_ops.c
> index 22c5251..b0da096 100644
> --- a/lib/librte_mempool/rte_mempool_ops.c
> +++ b/lib/librte_mempool/rte_mempool_ops.c
> @@ -17,6 +17,15 @@ struct rte_mempool_ops_table rte_mempool_ops_table = {
>         .num_ops = 0
>  };
>
> +static int
> +compare_mempool_ops(const void *a, const void *b)
> +{
> +       const struct rte_mempool_ops *m_a = a;
> +       const struct rte_mempool_ops *m_b = b;
> +
> +       return strcmp(m_a->name, m_b->name);
> +}
> +
>  /* add a new ops struct in rte_mempool_ops_table, return its index. */
>  int
>  rte_mempool_register_ops(const struct rte_mempool_ops *h)
> @@ -63,6 +72,13 @@ struct rte_mempool_ops_table rte_mempool_ops_table = {
>         ops->get_info = h->get_info;
>         ops->dequeue_contig_blocks = h->dequeue_contig_blocks;
>
> +       /*
> +        * sort the rte_mempool_ops by name. the order of the mempool
> +        * lib initialization will not affect rte_mempool_ops index.
> +        */
> +       qsort(rte_mempool_ops_table.ops, rte_mempool_ops_table.num_ops,
> +             sizeof(rte_mempool_ops_table.ops[0]), compare_mempool_ops);
> +
>         rte_spinlock_unlock(&rte_mempool_ops_table.sl);
>
>         return ops_index;
> --
> 1.8.3.1
>