On Wed, Mar 4, 2020 at 6:48 PM Tonghao Zhang <xiangxia.m....@gmail.com> wrote:
>
> On Mon, Mar 2, 2020 at 9:45 PM Jerin Jacob <jerinjac...@gmail.com> wrote:
> >
> > On Mon, Mar 2, 2020 at 7:27 AM <xiangxia.m....@gmail.com> wrote:
> > >
> > > From: Tonghao Zhang <xiangxia.m....@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....@gmail.com>
> > > ---
> > > lib/librte_mempool/rte_mempool_ops.c | 18 ++++++++++++++++--
> > > 1 file changed, 16 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/lib/librte_mempool/rte_mempool_ops.c
> > > b/lib/librte_mempool/rte_mempool_ops.c
> > > index 22c5251..06dfe16 100644
> > > --- a/lib/librte_mempool/rte_mempool_ops.c
> > > +++ b/lib/librte_mempool/rte_mempool_ops.c
> > > @@ -22,7 +22,7 @@ struct rte_mempool_ops_table rte_mempool_ops_table = {
> > > rte_mempool_register_ops(const struct rte_mempool_ops *h)
> > > {
> > > struct rte_mempool_ops *ops;
> > > - int16_t ops_index;
> > > + unsigned ops_index, i;
> > >
> > > rte_spinlock_lock(&rte_mempool_ops_table.sl);
> > >
> > > @@ -50,7 +50,19 @@ struct rte_mempool_ops_table rte_mempool_ops_table = {
> > > return -EEXIST;
> > > }
> > >
> > > - ops_index = rte_mempool_ops_table.num_ops++;
> > > + /* sort the rte_mempool_ops by name. the order of the mempool
> > > + * lib initiation will not affect rte_mempool_ops index. */
> >
> > +1 for the fix.
> > For the implementation, why not use qsort_r() for sorting?
> The implementation is easy, and the number of mempool driver is not too large.
> But we can use the qsort_r to implement it.
Since it is in a slow path, IMO, better to use standard sort functions
for better readability.
> >
> > > + ops_index = rte_mempool_ops_table.num_ops;
> > > + for (i = 0; i < rte_mempool_ops_table.num_ops; i++) {
> > > + if (strcmp(h->name, rte_mempool_ops_table.ops[i].name) <
> > > 0) {
> > > + do {
> > > + rte_mempool_ops_table.ops[ops_index] =
> > > +
> > > rte_mempool_ops_table.ops[ops_index -1];
> > > + } while (--ops_index > i);
> > > + break;
> > > + }
> > > + }
> > > +
> > > ops = &rte_mempool_ops_table.ops[ops_index];
> > > strlcpy(ops->name, h->name, sizeof(ops->name));
> > > ops->alloc = h->alloc;
> > > @@ -63,6 +75,8 @@ struct rte_mempool_ops_table rte_mempool_ops_table = {
> > > ops->get_info = h->get_info;
> > > ops->dequeue_contig_blocks = h->dequeue_contig_blocks;
> > >
> > > + rte_mempool_ops_table.num_ops++;
> > > +
> > > rte_spinlock_unlock(&rte_mempool_ops_table.sl);
> > >
> > > return ops_index;
> > > --
> > > 1.8.3.1
> > >
>
>
>
> --
> Thanks,
> Tonghao
