On 08/13, Oleg Nesterov wrote: > > On 08/13, Ravi Bangoria wrote: > > > > > But damn, process creation (exec) is trivial. We could add a new > > > uprobe_exec() > > > hook and avoid delayed_uprobe_install() in uprobe_mmap(). > > > > I'm sorry. I didn't get this. > > Sorry for confusion... > > I meant, if only exec*( could race with _register(), we could add another > uprobe > hook which updates all (delayed) counters before return to user-mode. > > > > Afaics, the really problematic case is dlopen() which can race with > > > _register() > > > too, right? > > > > dlopen() should internally use mmap() right? So what is the problem here? > > Can > > you please elaborate. > > What I tried to say is that we can't avoid > uprobe_mmap()->delayed_uprobe_install() > because dlopen() can race with _register() too, just like exec.
I'm afraid I added even more confusion... so let me clarify although I am sure you understand this better than me ;) of course, the main reason why we can't avoid uprobe_mmap()->delayed_uprobe_install() is not the race with _register(), the main reason is that dlopen() can mmap the code first, then mmap the counter we need to increment. Again, just like exec, but exec is "atomic" in that it can't return to user-mode until evrything is done, so we could add another uprobe hook and avoid delayed_uprobe_install in uprobe_mmap(). Just in case my previous email was not clear. Oleg.
