[dpdk-dev] [PATCH v4 1/2] librte_ether: add protection against overwrite device data

[Kerlin, MarcinX]

Hi Reshma,

> -----Original Message-----
> From: Pattan, Reshma
> Sent: Wednesday, September 28, 2016 4:04 PM
> To: Kerlin, MarcinX <marcinx.kerlin at intel.com>; dev at dpdk.org
> Cc: De Lara Guarch, Pablo <pablo.de.lara.guarch at intel.com>;
> thomas.monjalon at 6wind.com; Kerlin, MarcinX <marcinx.kerlin at intel.com>
> Subject: RE: [dpdk-dev] [PATCH v4 1/2] librte_ether: add protection against
> overwrite device data
> 
> 
> 
> > -----Original Message-----
> > From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Marcin Kerlin
> > Sent: Tuesday, September 27, 2016 12:13 PM
> > To: dev at dpdk.org
> > Cc: De Lara Guarch, Pablo <pablo.de.lara.guarch at intel.com>;
> > thomas.monjalon at 6wind.com; Kerlin, MarcinX <marcinx.kerlin at intel.com>
> > Subject: [dpdk-dev] [PATCH v4 1/2] librte_ether: add protection
> > against overwrite device data
> >
> > +int
> > +rte_eth_dev_release_dev_data(uint8_t port_id) {
> > +	char device[RTE_ETH_NAME_MAX_LEN];
> > +	struct rte_eth_dev_data *eth_dev_data = NULL;
> > +
> > +
> > @@ -631,6 +691,8 @@ int
> >  rte_eth_dev_detach(uint8_t port_id, char *name)  {
> >  	struct rte_pci_addr addr;
> > +	struct rte_eth_dev_data *eth_dev_data = NULL;
> > +	char device[RTE_ETH_NAME_MAX_LEN];
> >  	int ret = -1;
> >
> >  	if (name == NULL) {
> > @@ -642,6 +704,15 @@ rte_eth_dev_detach(uint8_t port_id, char *name)
> >  	if (rte_eth_dev_is_detachable(port_id))
> >  		goto err;
> >
> > +	/* get device name by port id */
> > +	if (rte_eth_dev_get_name_by_port(port_id, device))
> > +		goto err;
> > +
> > +	/* look for an entry in the shared device data */
> > +	eth_dev_data = rte_eth_dev_get_dev_data_by_name(device);
> > +	if (eth_dev_data == NULL)
> > +		goto err;
> > +
> >  	if (rte_eth_dev_get_device_type(port_id) == RTE_ETH_DEV_PCI) {
> >  		ret = rte_eth_dev_get_addr_by_port(port_id, &addr);
> >  		if (ret < 0)
> > @@ -661,6 +732,9 @@ rte_eth_dev_detach(uint8_t port_id, char *name)
> >  			goto err;
> >  	}
> >
> > +	/* clear an entry in the shared device data */
> > +	memset(eth_dev_data, 0, sizeof(struct rte_eth_dev_data));
> > +
> >  	return 0;
> >
> 
> In this function, the new code chunks  together is nothing but the function "
> rte_eth_dev_release_dev_data()".
> So u can call the function itself rather than a duplicate code.

It was intentional, reason:

If I call function in place:
(1) beginning: then I lose device name for function below rte_eth_dev_detach_vdev (1.1):
	a) this is important for drivers  that hold name in shared rte_eth_dev_data[]
	b) not important for drivers that prepare own rte_eth_dev_data e.g pcap (rte_eth_pcap.c, line 816)

(2) end: then I lose device name for my function rte_eth_dev_release_dev_data, because in the above function 
rte_eth_dev_detach_vdev (1.1) for e.g pcap is call rte_free(eth_dev->data) which removes me a pointer to the
name (rte_eth_pcap.c, line 1079).


rte_eth_dev_detach (uint8_t port_id, char *name){
...
	(1) rte_eth_dev_release_dev_data(port_id);

	if (rte_eth_dev_get_device_type(port_id) == RTE_ETH_DEV_PCI) {
		ret = rte_eth_dev_get_addr_by_port(port_id, &addr);
		if (ret < 0)
			goto err;

		ret = rte_eth_dev_detach_pdev(port_id, &addr);
		if (ret < 0)
			goto err;

		snprintf(name, RTE_ETH_NAME_MAX_LEN,
			"%04x:%02x:%02x.%d",
			addr.domain, addr.bus,
			addr.devid, addr.function);
	} else {
		(1.1) ret = rte_eth_dev_detach_vdev(port_id, name);
		if (ret < 0)
			goto err;
	}

	(2) rte_eth_dev_release_dev_data(port_id);
...
}

This is reason why I keep name at the beginning but I release the name at the end function after detach.
At this point I do not see how the code directly replace by one function call.

Regards,
Marcin
> 
> Thanks,
> Reshma