Re: [PATCH] ntdll: Set Rip in for longjmp in RtlRestoreContext (try2)

[Piotr Caban]

Hi Daniel,

On 08/18/16 18:29, Daniel Lehman wrote:
> - pass = 0;
> - pRtlCaptureContext(&ctx);
> - if (InterlockedIncrement(&pass) == 1) /* interlocked to prevent compiler from moving */

The patch looks good for me except one thing that I don't understand. 
Why there's no risk that compiler will move the pass=0 assignment after 
pRtlCaptureContext call? Maybe something like this will be more correct:
pass = 0;
InterlockedIncrement(&pass);
pRtlCaptureContext(&ctx);
if (InterlockedIncrement(&pass) == 2)
?

Thanks,
Piotr

[PATCH] ntdll: Set Rip in for longjmp in RtlRestoreContext (try2)

[Daniel Lehman]

On 08/18/16 18:29, Daniel Lehman wrote:
> - pass = 0;
> - pRtlCaptureContext(&ctx);
> - if (InterlockedIncrement(&pass) == 1) /* interlocked to prevent
> - compiler from moving */

The patch looks good for me except one thing that I don't understand. 
Why there's no risk that compiler will move the pass=0 assignment after pRtlCaptureContext call?

I can see how another compiler could move it; just didn't in my case.  I'll send an updated version