Messages in this thread |  | | Date | Fri, 16 Aug 2002 11:49:23 +0200 (CEST) | From | Ingo Molnar <> | Subject | Re: [patch] user-vm-unlock-2.5.31-A2 |
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On Thu, 15 Aug 2002, Linus Torvalds wrote:
> The problem spot is the _fork_ from process X. Which gives a address in > process' _X_ virtual address space - used for SETTID. > > See? Process _X_ is not threaded, and is not maintaining any thread data > structures.
okay, this is the misunderstanding then. If it fork()s and then uses some threading (which uses clone()) then in all cases i know about it must be linked against some threading library. Otherwise Y couldnt do a clone() call and expect threading to work. In theory Y could 'become' a threading-capable process, but right now no threading library i'm aware of allows this - lots of standard C calls must be threading-aware and threading-safe. So right now 'threading' is a property that comes with the process image at exec() time. But this must not be so from a conceptual angle, so i agree with you.
(but the question is mostly academic anyway, because it makes perfect sense to use a pure SETTID for a completely unthreaded application, to get the fork() PID return value in the child's context as well.)
Ingo
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