RE: [PATCH v5 1/5] x86/sgx: Introduce a counter to count the sgx_(vepc_)open()

[Reshetova, Elena]

> > > > diff --git a/arch/x86/kernel/cpu/sgx/driver.c
> > > b/arch/x86/kernel/cpu/sgx/driver.c
> > > > index 7f8d1e11dbee..b5ffe104af4c 100644
> > > > --- a/arch/x86/kernel/cpu/sgx/driver.c
> > > > +++ b/arch/x86/kernel/cpu/sgx/driver.c
> > > > @@ -19,6 +19,7 @@ static int sgx_open(struct inode *inode, struct file
> *file)
> > > >  	struct sgx_encl *encl;
> > > >  	int ret;
> > > >
> > > > +	sgx_inc_usage_count();
> > >
> > > This should be done at the end of sgx_open() where the open cannot fail,
> > > since
> > > sgx_release() is not called if sgx_open() failed AFAICT.
> >
> >
> > Could you please elaborate a bit more on this?
> > In case sgx_inc_usage_count fails, we dont allocate resources yet, so what is
> > wrong?
> >
> 
> I haven't looked into (details of) the last patch yet, but for _this_ patch
> only, doing sgx_inc_usage_count() at the beginning of sgx_open() will result in
> the usage count being increased even when sgx_open() fails at a later time.
> Since sgx_release() is not called when sgx_open() fails, the usage count will
> not be decreased correctly.
> 
> No?

Yes, I already yesterday understood that you meant *this* patch and
yes, you are correct in this patch it must be moved to the end that we
don't increment in case of failures.