Re: [PATCH v14 5/5] x86/sgx: Enable automatic SVN updates for SGX enclaves

[Huang, Kai]

On Thu, 2025-08-14 at 09:50 -0700, Dave Hansen wrote:
> On 8/14/25 00:34, Elena Reshetova wrote:
> > +/* Mutex to ensure no concurrent EPC accesses during EUPDATESVN */
> > +static DEFINE_MUTEX(sgx_svn_lock);
> > +
> >  int sgx_inc_usage_count(void)
> >  {
> > +	int ret;
> > +
> > +	guard(mutex)(&sgx_svn_lock);
> > +
> > +	if (!sgx_usage_count) {
> > +		ret = sgx_update_svn();
> > +		if (ret)
> > +			return ret;
> > +	}
> > +
> > +	sgx_usage_count++;
> > +
> >  	return 0;
> >  }
> >  
> >  void sgx_dec_usage_count(void)
> >  {
> > -	return;
> > +	sgx_usage_count--;
> >  }
> 
> How is a plain int-- safe?
> 
> Where's the locking?

Sorry I missed this during review too.