Messages in this thread | | | Date | Tue, 30 Sep 2008 09:40:25 +0800 | From | Lai Jiangshan <> | Subject | Re: [PATCH] markers: fix unregister bug and reenter bug |
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Mathieu Desnoyers wrote: > Hi Lai, > > I'll have to nack this fix : > > One fix I already posted makes sure every marker unregister callers call > synchronize_sched() _at some point_ before module unload. It thus makes > sure we can do batch unregistration without doing multiple > synchronize_sched calls.
1) the new API marker_synchronize_unregister() is ugly, it separate one thing into two steps. user have to remember to call marker_synchronize_unregister() and have to know what he can do and what he can't do before marker_synchronize_unregister().
2) IMO, synchronous code is better than asynchronous in non-critical-path. we need synchronize_sched() for free(old).
you fixes haven't fix the reenter bug.
I recommend my fix.
> > Also, there is no need to do the synchronize_sched with the marker mutex > held. call_rcu_sched takes care of making sure the previous quiescent > state is over before calling kfree. This means that when we return from > the register/unregister functions, there may still be markers "in > flight" using the old markers. Again, why would it be a problem ? > > Thanks, > > Mathieu > > P.S. : I'll send along the patches I am referring to. Ingo, those should > probably be merged if they are not in -tip already. >
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