Messages in this thread | | | Date | Tue, 15 Apr 2003 08:01:42 -0700 | From | John Reiser <> | Subject | Re: observe & control thread state for exit futex ? |
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Daniel Jacobowitz wrote: > On Sun, Apr 13, 2003 at 07:52:08PM -0700, John Reiser wrote: > >>How can a debugger, newly attached to an arbitrary thread, determine whether >>the thread has a pending exit futex and associated memory location to clear >>[CLONE_CHILD_CLEARTID flag and child_tid_ptr parameter at __clone()]? >> >>If so, then how can the debugger determine the address, change the address, >>cancel the futex, and/or intercept the notification? > > > It can't. Even clone flags are not accessible. > > If you can think of a good reason that a debugger would need any > particular piece of data, exposing it is very straightforward. >
The debugger needs this information to determine the state of the thread. An automated software audit program needs the information to verify that threads are working correctly. In general, write-only state [from the viewpoint of the thread] is a bad idea.
Would a new option to sys_prctl() be a good way to expose the data?
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