Messages in this thread | | | Date | Mon, 6 Aug 2018 18:34:36 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH 3/2] perf/hw_breakpoint: Remove superfluous bp->attr.disabled = 0 new attr has disabled set |
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On 08/06, Jiri Olsa wrote: > > 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; > - } > +
Yes, but again, this still looks confusing.
IMO, we should either remove "bp->attr.disabled = attr->disabled" in modify_user_hw_breakpoint_check() because bp->attr.disabled is not really used, or we should set bp->attr.disabled = 1 on failure just for consistency.
Hmm... actually ptrace_get_dr7() checks ->attr.disabled, so we can hit WARN_ON(second_pass) in ptrace_write_dr7() in case when attr.disabled is falsely 0 because modify_user_hw_breakpoint_check() failed before?
It seems I am totally confused and need to sleep ;)
Oleg.
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