Messages in this thread | | | Date | Fri, 29 Sep 2017 19:45:28 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH -tip v3 7/7] kprobes: Use synchronize_rcu_tasks() for optprobe with CONFIG_PREEMPT |
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* Masami Hiramatsu <mhiramat@kernel.org> wrote:
> On Fri, 29 Sep 2017 09:37:55 +0200 > Ingo Molnar <mingo@kernel.org> wrote: > > > > > * Masami Hiramatsu <mhiramat@kernel.org> wrote: > > > > > On Thu, 28 Sep 2017 09:22:20 +0200 > > > Ingo Molnar <mingo@kernel.org> wrote: > > > > > > > > > > > * Masami Hiramatsu <mhiramat@kernel.org> wrote: > > > > > > > > > To enable jump optimized probe with CONFIG_PREEMPT, use > > > > > synchronize_rcu_tasks() to wait for all tasks preempted > > > > > on trampoline code back on track. > > > > > > > > This sentence does not parse. It's missing a verb, but I'm not sure. > > > > > > Hmm, how about this? > > > > > > Use synchthnize_rcu_tasks() to wait for all tasks preempted > > > on trampoline code back on track so that jump optimized probe > > > can be enabled with CONFIG_PREEMPT. > > > > What's "synchthnize"? ... > > Oops, it's my typo. my XPS touch pad is really unstable... > > > > > More seriously, I still don't understand it. What is 'back on track'? > > > > Do you mean to say: > > > > We want to wait for all potentially preempted kprobes trampoline execution to > > have completed. This guarantees that any freed trampoline memory is not in use > > by any task in the system anymore. synchronize_rcu_tasks() gives such a > > guarantee, so use it. > > Exactly, this is correct!
Ok, great - please re-send the remaining kprobes patches that I have not applied yet - I'll read through the changelogs and fix any bits that might still be unclear.
Thanks,
Ingo
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