Messages in this thread |  | | | Date | Sat, 14 Jul 2007 15:20:02 -0400 | | From | Mathieu Desnoyers <> | | Subject | Re: [patch 1/8] Kprobes - do not use kprobes mutex in arch code |
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* Christoph Hellwig (hch@infradead.org) wrote: > On Fri, Jul 13, 2007 at 09:21:34PM -0400, Mathieu Desnoyers wrote: > > Remove the kprobes mutex from kprobes.h, since it does not belong there. Also > > remove all use of this mutex in the architecture specific code, replacing it by > > a proper mutex lock/unlock in the architecture agnostic code. > > This is not very nice for avr32/sparc64 which have a noop arch_remove_kprobe > and now need to take a mutex to do nothing. Maybe you can find a nice > way to avoid that? > > Except for this issue making kprobes_mutex static to kprobes.c sounds like > a good improvement. >
Since only unregister_kprobe() calls arch_remove_kprobe(), and only after having removed the struct kprobe from the kprobes list (while the kprobes mutex is held), I wonder if there is any need to hold the kprobes mutex at all when calling arch_remove_kprobe(). It turns out that only get_insn_slot()/free_insn_slot() (which is in kernel/kprobes.c, but called from arch specific code) seems to really use protection of this mutex.
Would it make sense to protect the kprobe_insn_pages list with a new kprobe_insn_mutex, nestable in the kprobe_mutex ?
-- Mathieu Desnoyers Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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