I found the problem two weeks ago, but I can not find a better way to
avoid userret() to be called twice. so I keep silence. :(
Gartner: Apache is vulnerable, we recommend switching back to IIS to protect yourselves
----- Original Message -----
From: "Julian Elischer" <[EMAIL PROTECTED]>
To: "FreeBSD current users" <[EMAIL PROTECTED]>
Sent: Tuesday, July 09, 2002 2:40 PM
Subject: userret() , ast() and the end of syscalls
> A question to those who know..
> why is userret() called both at the end of trap() or syscall()
> and also almost immediatly again (often) at the end of ast().
> It seems that really there is no one place that one can put code that will
> be called ONCE and ONLY ONCE as a thread progresses to userland.
> There is no one place where you can say "after this point we are in
> userland" right up until that iret instruction. There is always the danger
> that FTER ny insruction that decides that we are now definitly going to
> user space, there could occur an interrupt that causes a reschedule so
> that some OTHER thread goes to user land.
> Is it possible to clear interrupts and have the iret instruction
> itself re-enable them?
> (that would give a few instructions 'atomically' with the iret
> which may be all I need).
> is this possible in other architectures?
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