* Reshetova, Elena <elena.reshet...@intel.com> wrote:
>
> > * Elena Reshetova <elena.reshet...@intel.com> wrote:
> >
> > > @@ -19,10 +19,15 @@ static int sgx_open(struct inode *inode, struct file
> > *file)
> > > struct sgx_encl *encl;
> > > int ret;
> > >
> > > + ret = sgx_inc_usage_count();
> > > + if (ret)
> > > + return -EBUSY;
> >
> > So if sgx_inc_usage_count() returns nonzero, it's in use already and we
> > return -EBUSY, right?
>
> I guess my selection of error code here was wrong.
> The intended logic is if sgx_inc_usage_count() returns nonzero,
> the *incrementing of counter failed* (due to failed EUPDATESVN)
> and we want to stop and report error.
>
> >
> > But:
> >
> > > int sgx_inc_usage_count(void)
> > > {
> > > + int ret;
> > > +
> > > + /*
> > > + * Increments from non-zero indicate EPC other
> > > + * active EPC users and EUPDATESVN is not attempted.
> > > + */
> > > + if (atomic64_inc_not_zero(&sgx_usage_count))
> > > + return 0;
> >
> > If sgx_usage_count is 1 here (ie. it's busy), this will return *zero*,
> > and sgx_open() will not run into the -EBUSY condition and will continue
> > assuming it has claimed the usage count, while it hasn't ...
>
> Yes, meaning is different, see above.
So that's rather convoluted:
atomic64_inc_not_zero(): returns 1 on successful increase, 0 on
failure
sgx_inc_usage_count(): returns 0 on successful increase, 1 on
failure
sgx_open(): returns 0 on successful increase, -EBUSY on
failure
Could we at least standardize sgx_inc_usage_count() on -EBUSY in the
failure case, so it's a more obvious pattern:
+ ret = sgx_inc_usage_count();
+ if (ret < 0)
+ return ret;
Thanks,
Ingo
