Re: [dpdk-dev] [dpdk-stable] [PATCH] net/tap: fix memory leak when unregister intr handler

[wangyunjian <wangyunjian@huawei.com>]

> -----Original Message-----
> From: Ferruh Yigit [mailto:ferruh.yigit@intel.com]
> Sent: Monday, January 20, 2020 8:43 PM
> To: wangyunjian <wangyunjian@huawei.com>; dev@dpdk.org;
> keith.wiles@intel.com
> Cc: xudingke <xudingke@huawei.com>; stable@dpdk.org
> Subject: Re: [dpdk-stable] [dpdk-dev] [PATCH] net/tap: fix memory leak when
> unregister intr handler
> 
> On 1/20/2020 8:30 AM, Yunjian Wang wrote:
> > The return check of function tap_lsc_intr_handle_set() is wrong, it should
> > be 0 or a positive number if success. So the intr_handle->intr_vec was not
> > been freed when tap_lsc_intr_handle_set() returned a positive number.
> >
> > Fixes: 4870a8cdd968 ("net/tap: support Rx interrupt")
> > Cc: stable@dpdk.org
> >
> > Signed-off-by: Yunjian Wang <wangyunjian@huawei.com>
> > ---
> >  drivers/net/tap/rte_eth_tap.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/tap/rte_eth_tap.c b/drivers/net/tap/rte_eth_tap.c
> > index a13d8d50d..079310fea 100644
> > --- a/drivers/net/tap/rte_eth_tap.c
> > +++ b/drivers/net/tap/rte_eth_tap.c
> > @@ -1591,8 +1591,10 @@ tap_intr_handle_set(struct rte_eth_dev *dev, int
> set)
> >  	int err;
> >
> >  	err = tap_lsc_intr_handle_set(dev, set);
> > -	if (err)
> > +	if (err < 0) {
> 
> +1 to "err < 0", it seems 'tap_lsc_intr_handle_set()' can return positive on
> success for 'rte_intr_callback_unregister()' path.
> 
> > +		tap_rx_intr_vec_set(dev, 0);
> 
> for the case "set == 1", this function may be called and it will try to free
> some resources, but this may cause redundant free calls and cause segfault,
> did
> you able to have any chance to test this mentioned path?
> What about putting a "if (!set)" before calling this function?
> 
I have tested this mentioned path and find nothing wrong.
I will send the v2 later according to Ferruh's suggestions.

Thanks,
Yunjian
> >  		return err;
> > +	}
> >  	err = tap_rx_intr_vec_set(dev, set);
> >  	if (err && set)
> >  		tap_lsc_intr_handle_set(dev, 0);
> >