Messages in this thread | | | Date | Thu, 16 Jun 2011 15:24:12 +0530 | From | Srikar Dronamraju <> | Subject | Re: [PATCH v4 3.0-rc2-tip 4/22] 4: Uprobes: register/unregister probes. |
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* Peter Zijlstra <peterz@infradead.org> [2011-06-16 11:46:22]:
> On Thu, 2011-06-16 at 09:41 +0530, Srikar Dronamraju wrote: > > * Peter Zijlstra <peterz@infradead.org> [2011-06-15 19:41:59]: > > > > > On Tue, 2011-06-07 at 18:29 +0530, Srikar Dronamraju wrote: > > > > 1. Use mm->owner and walk thro the thread_group of mm->owner, siblings > > > > of mm->owner, siblings of parent of mm->owner. This should be > > > > good list to traverse. Not sure if this is an exhaustive > > > > enough list that all tasks that have a mm set to this mm_struct are > > > > walked through. > > > > > > As per copy_process(): > > > > > > /* > > > * Thread groups must share signals as well, and detached threads > > > * can only be started up within the thread group. > > > */ > > > if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND)) > > > return ERR_PTR(-EINVAL); > > > > > > /* > > > * Shared signal handlers imply shared VM. By way of the above, > > > * thread groups also imply shared VM. Blocking this case allows > > > * for various simplifications in other code. > > > */ > > > if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM)) > > > return ERR_PTR(-EINVAL); > > > > > > CLONE_THREAD implies CLONE_VM, but not the other way around, we > > > therefore would be able to CLONE_VM and not be part of the primary > > > owner's thread group. > > > > > > This is of course all terribly sad.. > > > > Agree, > > > > If clone(CLONE_VM) were to be done by a thread_group leader, we can walk > > thro the siblings of parent of mm->owner. > > > > However if clone(CLONE_VM) were to be done by non thread_group_leader > > thread, then we dont even seem to add it to the init_task. i.e I dont > > think we can refer to such a thread even when we walk thro > > do_each_thread(g,t) { .. } while_each_thread(g,t); > > > > right? > > No, we initialize p->group_leader = p; and only change that for > CLONE_THREAD, so a clone without CLONE_THREAD always results in a new > thread group leader, which are always added to the init_task list. >
Ahh .. I missed the p->group_leader = p thing.
In which case, shouldnt traversing all the tasks of all siblings of parent of mm->owner should provide us all the the tasks that have linked to mm. Right?
Agree that we can bother about this a little later.
-- Thanks and Regards Srikar
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