Messages in this thread Patch in this message | | | Date | Mon, 6 Aug 2018 17:08:36 +0200 | From | Jiri Olsa <> | Subject | [PATCH 3/2] perf/hw_breakpoint: Remove superfluous bp->attr.disabled = 0 new attr has disabled set |
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On Mon, Aug 06, 2018 at 03:23:53PM +0200, Jiri Olsa wrote: > 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
like this ;-)
jirka
--- Once the breakpoint was succesfully modified, the attr->disabled value is in bp->attr.disabled. So there's no reason to set it again, removing that.
Link: http://lkml.kernel.org/n/tip-v5oaellzsmyszv3rfucuxkp0@git.kernel.org Signed-off-by: Jiri Olsa <jolsa@kernel.org> --- kernel/events/hw_breakpoint.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c index fb229d9c7f3c..3e560d7609fd 100644 --- a/kernel/events/hw_breakpoint.c +++ b/kernel/events/hw_breakpoint.c @@ -526,10 +526,9 @@ int modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *att if (err) return err; - if (!attr->disabled) { + if (!attr->disabled) perf_event_enable(bp); - bp->attr.disabled = 0; - } + return 0; } EXPORT_SYMBOL_GPL(modify_user_hw_breakpoint); -- 2.17.1
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