On Sun, Jun 21, 2020 at 10:01:24AM +0300, Yishai Hadas wrote:
> On 6/19/2020 3:29 PM, Jason Gunthorpe wrote:
> > On Wed, Jun 17, 2020 at 10:45:46AM +0300, Yishai Hadas wrote:
> > > +static struct ibv_context *verbs_import_device(int cmd_fd)
> > > +{
> > > + struct verbs_device *verbs_device = NULL;
> > > + struct verbs_context *context_ex;
> > > + struct ibv_device **dev_list;
> > > + struct ibv_context *ctx = NULL;
> > > + struct stat st;
> > > + int i;
> > > +
> > > + if (fstat(cmd_fd, &st) || !S_ISCHR(st.st_mode)) {
> > > + errno = EINVAL;
> > > + return NULL;
> > > + }
> > > +
> > > + dev_list = ibv_get_device_list(NULL);
> > > + if (!dev_list) {
> > > + errno = ENODEV;
> > > + return NULL;
> > > + }
> > > +
> > > + for (i = 0; dev_list[i]; ++i) {
> > > + if (verbs_get_device(dev_list[i])->sysfs->sysfs_cdev ==
> > > + st.st_rdev) {
> > > + verbs_device = verbs_get_device(dev_list[i]);
> > > + break;
> > > + }
> > > + }
> >
> > Unfortunately it looks like there is a small race here, the struct
> > ib_uverbs_file can exist beyond the lifetime of the cdev number - the
> > uverbs_ida is freed in ib_uverbs_remove_one() and files can still be
> > open past that point.
> >
>
> Are you referring to the option that we might end up with importing a device
> that was already dissociated ? the below call to ops->import_context() will
> just fail with -EIO upon calling on this FD to the query_context method, so
> I believe that we should be fine here.
Okay, lets have a comment then, it is tricky
Jason
