>
> +/* Mutex to ensure no concurrent EPC accesses during EUPDATESVN */
> +static DEFINE_MUTEX(sgx_svn_lock);
> +
> int sgx_inc_usage_count(void)
> {
> + guard(mutex)(&sgx_svn_lock);
> +
> + if (sgx_usage_count++ == 0)
> + return sgx_update_svn();
> +
Hmm.. sorry for not noticing this before.. But I think we might have a
problem here since the sgx_usage_count is increased regardless of the
result of sgx_update_svn().
If sgx_update_svn() fails, it makes sgx_inc_usage_count() return error
too, so sgx_{vepc_}open() will fail and return immediately w/o calling
sgx_dec_usage_count().
But the sgx_usage_count has been increased.
AFAICT when sgx_{vepc_}_open() fails, the sgx_{vepc_}release() is not
called, so sgx_dec_usage_count() is never called and sgx_usage_count
remains increased.
So when sgx_{vepc_}open() calls sgx_inc_usage_count() again, it will skip
calling sgx_update_svn(), and allow enclave/vEPC to be created
successfully, which just defeats the purpose.
So if I am not missing anything, I think we should only increase the count
when sgx_update_svn() returns success?
> return 0;
> }
>
> void sgx_dec_usage_count(void)
> {
> - return;
> + sgx_usage_count--;
> }
>
> static int __init sgx_init(void)
