Messages in this thread | | | Date | Wed, 22 Dec 2010 17:00:16 +0100 | From | Oleg Nesterov <> | Subject | Re: [PATCH 10/16] ptrace: clean transitions between TASK_STOPPED and TRACED |
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On 12/22, Tejun Heo wrote: > > On Wed, Dec 22, 2010 at 12:39:48PM +0100, Oleg Nesterov wrote: > > > > sys_ptrace() only works for the single thread who did PTRACE_ATTACH, > > but do_wait() should work for its sub-threads. > > > > 1. the tracer knows that the tracee is stopped > > > > 2. the tracer does ptrace(ATTACH) > > > > 3. the tracer's sub-thread does do_wait() > > > > Note! Personally I think we can ignore this "problem", I do not > > think it can break anything except some specialized test-case. > > But if ptrace(ATTACH) doesn't return until the transition is complete > when the task is already stopped, the tracer's sub-thread's do_wait() > will behave exactly the same. The only difference would be that > ptrace(ATTACH) may now block and/or is failed by a signal delivery. > > How would #3 behave differently if STOPPED -> TRACED transition is > guaranteed to be complete by the end of #2?
Ahhh, sorry. I meant, two threads can do 2. and 3. at the same time.
But let me repeat, it is not that I think we should worry. I mentioned this only because I think it is better to discuss everything we can, even the really minor things.
Oleg.
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