Re: [dpdk-dev] rte_eal_hotplug_remove() generates error message

[Hideyuki Yamashita <yamashita.hideyuki@po.ntt-tx.co.jp>]

Dear Thomas and all,

I took a look on dpdk code.
I firstly write qustions and my analisys 
on the current dpdk code follows after that.

[1.Questions]
I have several questions to ask again.
Is my understanding correct about followings

Q1: "EAL:ERROR, Invalid memory" is ignorable

Q2: there is no big difference between calling 
rte_eal_hotplug_remove(bus->name, dev->name)
and
rte_dev_remove(dev) because anyway it 
reaches to rte_pmd_vhost_remove and encounter 
the same error.

[2.snip from my code]
.....
        rte_eth_dev_close(port_id);
        ret = rte_dev_remove(dev);
        if (ret < 0)
                return ret;
        rte_eth_dev_release_port(&rte_eth_devices[port_id]);

[3. My analysis on dpdk code]
static int
  rte_pmd_vhost_remove(struct rte_vdev_device *dev)
  {
   ...........
        　eth_dev_close(eth_dev);

          rte_free(vring_states[eth_dev->data->port_id]);
          vring_states[eth_dev->data->port_id] = NULL;

          rte_eth_dev_release_port(eth_dev);

As you can see in rte_eth_vhost.c
It calls both eth_dev_close and rte_eth_dev_release_port.
And inside both functions, it tries to free mac_addrs. 
        rte_free(dev->data->mac_addrs);       //in rth_dev_close
        rte_free(eth_dev->data->mac_addrs);  //in rte_eth_dev_release_port

I understand that is the reason why 
/* Free the memory space back to heap */
void rte_free(void *addr)
{
        if (addr == NULL) return;
        if (malloc_heap_free(malloc_elem_from_data(addr)) < 0)
                RTE_LOG(ERR, EAL, "Error: Invalid memory\n");
}
encounter the error.
As an experiment, I commented out one of them, "ERR, Invalid memory"
disappered.

Thanks and BR,
Hideyuki Yamashita
NTT TechnoCross

> Adding my colleague Yasufumi and Hiroyuki as CC.
> 
> We are waiting valuable advice from you.
> 
> Thanks in advance,
> Hideyuki Yamashita
> NTT TechnoCross
> 
> > 
> > Dear Thomas and all,
> > 
> > I hope you all get safely back home after DPDK summit.
> > (When I get back Japan, it is chilling. (start of winter))
> > 
> > On DPDK 18.11.0, we tried to remove vhost device by using rte_eal_hotplug_remove().
> > However, following syslog message is printed.
> > “EAL: Error: Invalid memory”
> > 
> > At DPDK summit San Jose, we had chance to ask Thomas how to handle the error message, and he gave us following advice:
> > Replace “rte_eal_hotplug_add()” to “rte_dev_probe(devargs)” and
> > “rte_eal_hotplug_remove()” to “rte_eth_dev_close() and rte_dev_remove(rte_dev)”
> > 
> > We tested above changes, but the result is the same (i.e., same error message is printed).
> > The debug log message says:
> > ---
> > [primary]
> > VHOST_CONFIG: vhost-user server: socket created, fd: 17
> > VHOST_CONFIG: bind to /tmp/sock0
> > EAL: Error: Invalid memory
> > VHOST_CONFIG: vhost-user server: socket created, fd: 17
> > VHOST_CONFIG: bind to /tmp/sock0
> > 
> > [secondary]
> > APP: devargs=eth_vhost0,iface=/tmp/sock0,queues=1
> > EAL: request: eal_dev_mp_request
> > EAL: msg: eal_dev_mp_request
> > EAL: request: bus_vdev_mp
> > EAL: msg: bus_vdev_mp
> > EAL: msg: bus_vdev_mp
> > EAL: reply: eal_dev_mp_request
> > EAL: msg: eal_dev_mp_request
> > rte_eth_promiscuous_disable: Function not supported
> > rte_eth_allmulticast_disable: Function not supported
> > APP: To Server: add
> > EAL: request: eal_dev_mp_request
> > EAL: msg: eal_dev_mp_request
> > EAL: reply: eal_dev_mp_request
> > EAL: msg: eal_dev_mp_request
> > APP: To Server: del
> > APP: devargs=eth_vhost0,iface=/tmp/sock0,queues=1
> > EAL: request: eal_dev_mp_request
> > EAL: msg: eal_dev_mp_request
> > EAL: request: bus_vdev_mp
> > EAL: msg: bus_vdev_mp
> > EAL: msg: bus_vdev_mp
> > EAL: reply: eal_dev_mp_request
> > EAL: msg: eal_dev_mp_request
> > rte_eth_promiscuous_disable: Function not supported
> > rte_eth_allmulticast_disable: Function not supported
> > APP: To Server: add
> > ---
> > 
> > We would like to ask:
> > 1)	Is the message “EAL: Error: Invalid memory” ignorable or not? There is no obstacle except this message to re-add the vhost device.
> > 2)	Which is the better(best?) way to add/del vhost device “rte_eal_hotplug_add/remove()” or the way Thomas suggested?
> > 
> > Thanks in advance and have a nice day.
> > 
> > BR,
> > Hideyuki Yamashita
> > NTT TechnoCross
>