Messages in this thread | | | Date | Mon, 6 Aug 2018 15:23:53 +0200 | From | Jiri Olsa <> | Subject | Re: [PATCH 2/2] perf/hw_breakpoint: Modify breakpoint even if the new attr has disabled set |
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On Mon, Aug 06, 2018 at 02:48:40PM +0200, Oleg Nesterov wrote: > On 08/06, Jiri Olsa wrote: > > > > We need to change the breakpoint even if the attr with > > new fields has disabled set to true. > > Agreed... The patch looks fine to me, but I have a question > > > int modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *attr) > > { > > + int err; > > + > > /* > > * modify_user_hw_breakpoint can be invoked with IRQs disabled and hence it > > * will not be possible to raise IPIs that invoke __perf_event_disable. > > @@ -520,11 +522,11 @@ int modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *att > > else > > perf_event_disable(bp); > > > > - if (!attr->disabled) { > > - int err = modify_user_hw_breakpoint_check(bp, attr, false); > > + err = modify_user_hw_breakpoint_check(bp, attr, false); > > + if (err) > > + return err; > > > > - if (err) > > - return err; > > + if (!attr->disabled) { > > perf_event_enable(bp); > > bp->attr.disabled = 0; > > Afaics you do not need to clear attr.disabled, modify_user_hw_breakpoint_check() > updates it if err = 0. So I think > > if (!bp->attr.disabled) > perf_event_enable(bp); > > will look a bit better. > > > But, with or without this fix, shouldn't we set .disabled = 1 if modify_() fails? > IIUC this doesn't matter, bp->attr.disabled is not really used anyway, but looks a > bit confusing. >
yea, I was looking on that, but as u said it makes no difference and I wanted to keep the patch as simple as possible ;-)
I'll send something on top of this patch
jirka
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