On Tue, Feb 02, 2021 at 01:12:07PM +1300, Kai Huang wrote: > On Mon, 1 Feb 2021 09:23:18 -0800 Sean Christopherson wrote: > > On Mon, Feb 01, 2021, Dave Hansen wrote: > > > On 1/31/21 9:40 PM, Kai Huang wrote: > > > >>> - ret = sgx_drv_init(); > > > >>> + /* Success if the native *or* virtual EPC driver initialized cleanly. */ > > > >>> + ret = !!sgx_drv_init() & !!sgx_vepc_init(); > > > >> If would create more dumb code and just add > > > >> > > > >> ret = sgx_vepc_init() > > > >> if (ret) > > > >> goto err_kthread; > > > > > > Jarkko, I'm not sure I understand this suggestion. > > > > > > > Do you mean you want below? > > > > > > > > ret = sgx_drv_init(); > > > > ret = sgx_vepc_init(); > > > > if (ret) > > > > goto err_kthread; > > > > > > > > This was Sean's original code, but Dave didn't like it. > > > > The problem is it's wrong. That snippet would incorrectly bail if drv_init() > > succeeds but vepc_init() fails. > > > > The alternative to the bitwise AND is to snapshot the result in two separate > > variables: > > > > ret = sgx_drv_init(); > > ret2 = sgx_vepc_init(); > > if (ret && ret2) > > goto err_kthread; > > > > or check the return from drv_init() _after_ vepc_init(): > > > > ret = sgx_drv_init(); > > if (sgx_vepc_init() && ret) > > goto err_kthread; > > > > > > As evidenced by this thread, the behavior is subtle and easy to get wrong. I > > deliberately chose the option that was the weirdest specifically to reduce the > > probability of someone incorrectly "cleaning up" the code. > > > > > Are you sure? I remember the !!&!! abomination being Sean's doing. :) > > > > Yep! That 100% functionally correct horror is my doing. > > > > > > Sean/Dave, > > > > > > > > Please let me know which way you prefer. > > > > > > Kai, I don't really know you are saying here. In the end, > > > sgx_vepc_init() has to run regardless of whether sgx_drv_init() is > > > successful or not. Also, we only want to 'goto err_kthraed' if *BOTH* > > > fail. The code you have above will, for instance, 'goto err_kthread' if > > > sgx_drv_init() succeeds but sgx_vepc_init() fails. It entirely > > > disregards the sgx_drv_init() error code. > > > > Hi Dave, Sean, > > Yeah sorry my bad. The example I provided won't work. So I'd like keep the !! > &!! :) > > Thanks. > > Jarkko, please let us know if you still have concern. I'll just review the next version. I disagree with this packing though. /Jarkko
