Messages in this thread | | | Date | Sat, 14 Jul 2007 15:30:26 -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. >
While we are here:
The whole check_safety() in kprobes.c seems awkward.. freezing processes is probably costly, and the check:
if (p != current && p->state == TASK_RUNNING && p->pid != 0) {
Adds restrictions about where a probe can be safely put.. the idle thread becomes a restriction.
I suggest disabling preemption in the int3 handler, just before single-stepping, then reenabling it in the breakpoint handler executed right after the single-step. A synchronize_sched() could then replace the whole check_safety() and would never fail. The side-effect would be to disable preemption in the single-step, it's no big deal.
Mathieu
-- 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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