Messages in this thread | | | Date | Thu, 2 Aug 2012 22:24:52 +0530 | From | Srikar Dronamraju <> | Subject | Re: [PATCH] uprobes: Ignore unsupported instructions in uprobe_mmap |
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* Oleg Nesterov <oleg@redhat.com> [2012-08-02 16:17:57]:
> Forgot to mention... > > On 08/02, Srikar Dronamraju wrote: > > > > While at it, add a missing put_uprobe() in the path where uprobe_mmap() > > races with uprobe_unregister(). > > ... > > @@ -1051,8 +1051,10 @@ int uprobe_mmap(struct vm_area_struct *vma) > > if (ret == -EEXIST) { > > ret = 0; > > > > - if (!is_swbp_at_addr(vma->vm_mm, vaddr)) > > + if (!is_swbp_at_addr(vma->vm_mm, vaddr)) { > > + put_uprobe(uprobe); > > continue; > > + } > > Yes, this part looks correct. > > In fact, I think this is not really correct anyway (wrt counter) > but we are going to kill it. > >
Are you expecting the counter to be decreased/increased here?
This is case where the uprobe_mmap() and uprobe_unregister() raced, and by the time install_breakpoint() was called by uprobe_mmap(), there were no consumers. i.e there are no uprobe->consumers and the underlying instruction is still not a breakpoint instruction.
Since we are refusing to add a breakpoint and that there is no breakpoint, there is no need to increment/decrement the counter here.
Do let me know if I have missed something.
-- Thanks and Regards Srikar
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