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From: Matan Azrad <matan@mellanox.com>
To: Stephen Hemminger <stephen@networkplumber.org>
Cc: "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH] net/vdev_netvsc: fix erronous cast
Date: Sun, 17 Mar 2019 06:16:39 +0000	[thread overview]
Message-ID: <AM0PR0502MB4019B141117E70C139D1C516D2460@AM0PR0502MB4019.eurprd05.prod.outlook.com> (raw)
Message-ID: <20190317061639.gGRQcTsgyO5hTecCBzpUG9H05P1POr8tfkVlbMTpO6M@z> (raw)
In-Reply-To: <20190314084435.2cca9735@shemminger-XPS-13-9360>

Hi

From: Stephen Hemminger
> > Hi
> >
> > From: Stephen Hemminger
> > > The return value from bus->find_device is a rte_device which is not
> > > safe to cast to a rte_vdev_device structure.
> > > It doesn't really matter since only being checked for NULL but
> > > static checkers might find a bug here.
> > >
> >
> > Fix line is missing.
> >
> > > Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> > > ---
> > >  drivers/net/vdev_netvsc/vdev_netvsc.c | 7 ++++---
> > >  1 file changed, 4 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/net/vdev_netvsc/vdev_netvsc.c
> > > b/drivers/net/vdev_netvsc/vdev_netvsc.c
> > > index ba63fac2a598..801f54c96e01 100644
> > > --- a/drivers/net/vdev_netvsc/vdev_netvsc.c
> > > +++ b/drivers/net/vdev_netvsc/vdev_netvsc.c
> > > @@ -808,7 +808,7 @@ vdev_netvsc_cmp_rte_device(const struct
> > > rte_device *dev1,  static void
> > > vdev_netvsc_scan_callback(__rte_unused
> > > void *arg)  {
> > > -	struct rte_vdev_device *dev;
> > > +	struct rte_device *dev;
> > >  	struct rte_devargs *devargs;
> > >  	struct rte_bus *vbus = rte_bus_find_by_name("vdev");
> > >
> > > @@ -816,8 +816,9 @@ vdev_netvsc_scan_callback(__rte_unused void
> *arg)
> > >  		if (!strncmp(devargs->name, VDEV_NETVSC_DRIVER_NAME,
> > >  			     VDEV_NETVSC_DRIVER_NAME_LEN))
> > >  			return;
> > > -	dev = (struct rte_vdev_device *)vbus->find_device(NULL,
> > > -		vdev_netvsc_cmp_rte_device,
> > > VDEV_NETVSC_DRIVER_NAME);
> > > +
> > > +	dev = vbus->find_device(NULL, vdev_netvsc_cmp_rte_device,
> > > +				VDEV_NETVSC_DRIVER_NAME);
> >
> > Since the device must be vdev here,
> > It is better to use explicit cast to make the checker happy.
> 
> The cast is converting from rte_device to rte_vdev_device which incorrect.
> 
> The device returned by vbus->find_device is a rte_device not a
> rte_vdev_device:
> 
> vbus->find_device points to rte_vdev_find_device
> 
> struct rte_device *
> rte_vdev_find_device(const struct rte_device *start, rte_dev_cmp_t cmp,
> 		     const void *data)
> 
> but definition of rte_vdev_device is:
> 
> struct rte_vdev_device {
> 	TAILQ_ENTRY(rte_vdev_device) next;      /**< Next attached vdev */
> 	struct rte_device device;               /**< Inherit core device */
> };
> 
> The only safe way to get rte_vdev_device would be to use container_of().
> 
> 	dev = vbus->find_device(NULL, vdev_netvsc_cmp_rte_device,
> 				VDEV_NETVSC_DRIVER_NAME);
> 	vdev = dev ? container_of(dev, struct rte_vdev_device, device) :
> NULL;
> 
> But as the PATCH demonstrated, this is not necessary.

Yes, you right.
Please add fix line to the patch + stable line.


Matan

 


  parent reply	other threads:[~2019-03-17  6:16 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-13  2:12 Stephen Hemminger
2019-03-14 11:13 ` Matan Azrad
2019-03-14 11:13   ` Matan Azrad
2019-03-14 15:44   ` Stephen Hemminger
2019-03-14 15:44     ` Stephen Hemminger
2019-03-17  6:16     ` Matan Azrad [this message]
2019-03-17  6:16       ` Matan Azrad
2019-03-25 13:51       ` Ferruh Yigit
2019-03-25 13:51         ` Ferruh Yigit

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