Re: [PATCH] vDPA/ifcvf: match pointer check to use

[Tom Rix]

On 3/15/22 6:28 AM, Michael S. Tsirkin wrote:
> On Tue, Mar 15, 2022 at 05:41:30AM -0700, trix@xxxxxxxxxx wrote:
> > From: Tom Rix <trix@xxxxxxxxxx>
> >
> > Clang static analysis reports this issue
> > ifcvf_main.c:49:4: warning: Called function
> >    pointer is null (null dereference)
> >    vf->vring->cb.callback(vring->cb.private);
> >    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >
> > The check
> >    vring = &vf->vring[i];
> >    if (vring->cb.callback)
> >
> > Does not match the use.  Change dereference so they match.
> >
> > Fixes: 79333575b8bd ("vDPA/ifcvf: implement shared IRQ feature")
> Thanks a lot! I squashed this into the offending patch - no point in
> breaking bisect. Pushed to linux. However I'm now
> having second thoughts about applying that patchset - I'd like
> soma analysis explaining how this got through testing.

static analysis is something i do treewide.

There are currently ~2500 issues in linux-next, do not panic! many are 
false positives.

It is pretty easy to setup and once you have a baseline you can filter 
only your files.

Tom

> > Signed-off-by: Tom Rix <trix@xxxxxxxxxx>
> > ---
> >   drivers/vdpa/ifcvf/ifcvf_main.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c b/drivers/vdpa/ifcvf/ifcvf_main.c
> > index 3b48e717e89f7..4366320fb68d3 100644
> > --- a/drivers/vdpa/ifcvf/ifcvf_main.c
> > +++ b/drivers/vdpa/ifcvf/ifcvf_main.c
> > @@ -46,7 +46,7 @@ static irqreturn_t ifcvf_vqs_reused_intr_handler(int irq, void *arg)
> >   	for (i = 0; i < vf->nr_vring; i++) {
> >   		vring = &vf->vring[i];
> >   		if (vring->cb.callback)
> > -			vf->vring->cb.callback(vring->cb.private);
> > +			vring->cb.callback(vring->cb.private);
> >   	}
> >   
> >   	return IRQ_HANDLED;
> > --
> > 2.26.3