Re: [dpdk-dev] [PATCH 3/3] net/virtio_user: fix dev not freed after init error

["Tan, Jianfeng" <jianfeng.tan@intel.com>]

Hi Stephen,

> -----Original Message-----
> From: Stephen Hemminger [mailto:stephen@networkplumber.org]
> Sent: Saturday, August 6, 2016 12:34 AM
> To: Tan, Jianfeng
> Cc: dev@dpdk.org; yuanhan.liu@linux.intel.com; Wang, Zhihong;
> lining18@jd.com
> Subject: Re: [dpdk-dev] [PATCH 3/3] net/virtio_user: fix dev not freed after
> init error
> 
> On Fri,  5 Aug 2016 11:36:43 +0000
> Jianfeng Tan <jianfeng.tan@intel.com> wrote:
> 
> > diff --git a/drivers/net/virtio/virtio_user_ethdev.c
> b/drivers/net/virtio/virtio_user_ethdev.c
> > index daef09b..62ccb0b 100644
> > --- a/drivers/net/virtio/virtio_user_ethdev.c
> > +++ b/drivers/net/virtio/virtio_user_ethdev.c
> > @@ -313,6 +313,17 @@ virtio_user_eth_dev_alloc(const char *name)
> >  	return eth_dev;
> >  }
> >
> > +static void
> > +virtio_user_eth_dev_free(struct rte_eth_dev *eth_dev)
> > +{
> > +	struct rte_eth_dev_data *data = eth_dev->data;
> > +	struct virtio_hw *hw = data->dev_private;
> > +
> > +	rte_free(hw->virtio_user_dev);
> > +	rte_free(hw);
> > +	rte_eth_dev_release_port(eth_dev);
> > +}
> > +
> >  /* Dev initialization routine. Invoked once for each virtio vdev at
> >   * EAL init time, see rte_eal_dev_init().
> >   * Returns 0 on success.
> > @@ -328,7 +339,7 @@ virtio_user_pmd_devinit(const char *name, const
> char *params)
> >  	uint64_t queue_size = VIRTIO_USER_DEF_Q_SZ;
> >  	char *path = NULL;
> >  	char *mac_addr = NULL;
> > -	int ret = -1;
> > +	int result = -1, ret;
> 
> It is not clear why two return value variables are needed?

My purpose was to make "ret" to record the return value of intermediate functions, and "result" to record that of current method. Any convention to do that?

If it introduces confusions, I'll change to use only one return value variables.


> >
> >  	if (!params || params[0] == '\0') {
> >  		PMD_INIT_LOG(ERR, "arg %s is mandatory for virtio_user",
> > @@ -411,15 +422,19 @@ virtio_user_pmd_devinit(const char *name,
> const char *params)
> >
> >  	hw = eth_dev->data->dev_private;
> >  	if (virtio_user_dev_init(hw->virtio_user_dev, path, queues, cq,
> > -				 queue_size, mac_addr) < 0)
> > +				 queue_size, mac_addr) < 0) {
> > +		PMD_INIT_LOG(ERR, "virtio_user_dev_init fails");
> > +		virtio_user_eth_dev_free(eth_dev);
> >  		goto end;
> > +	}
> >
> >  	/* previously called by rte_eal_pci_probe() for physical dev */
> >  	if (eth_virtio_dev_init(eth_dev) < 0) {
> >  		PMD_INIT_LOG(ERR, "eth_virtio_dev_init fails");
> > +		virtio_user_eth_dev_free(eth_dev);
> >  		goto end;
> >  	}
> > -	ret = 0;
> > +	result = 0;
> >
> >  end:
> >  	if (kvlist)
> > @@ -428,7 +443,7 @@ end:
> >  		free(path);
> >  	if (mac_addr)
> >  		free(mac_addr);
> 
> Unrelated, but this code could eliminate those if () tests.

Thanks for the hint. Yes, as manual says, "If ptr is NULL, no operation is performed". "if"s can be eliminated.

Thanks,
Jianfeng

> 
> > -	return ret;
> > +	return result;
> >  }