Frederic Weisbecker <frede...@kernel.org> writes: > On Mon, May 28, 2018 at 09:31:07PM +1000, Michael Ellerman wrote: >> Frederic Weisbecker <frede...@kernel.org> writes: >> >> > On Thu, May 24, 2018 at 12:01:52PM +1000, Michael Ellerman wrote: >> >> Frederic Weisbecker <frede...@kernel.org> writes: >> >> >> >> > diff --git a/arch/powerpc/kernel/hw_breakpoint.c >> >> > b/arch/powerpc/kernel/hw_breakpoint.c >> >> > index 348cac9..fba6527 100644 >> >> > --- a/arch/powerpc/kernel/hw_breakpoint.c >> >> > +++ b/arch/powerpc/kernel/hw_breakpoint.c >> >> > @@ -139,30 +139,31 @@ int arch_bp_generic_fields(int type, int >> >> > *gen_bp_type) >> >> > /* >> >> > * Validate the arch-specific HW Breakpoint register settings >> >> > */ >> >> > -int arch_validate_hwbkpt_settings(struct perf_event *bp) >> >> > +int hw_breakpoint_arch_parse(struct perf_event *bp, >> >> > + struct perf_event_attr *attr, >> >> > + struct arch_hw_breakpoint *hw) >> >> >> >> I think the semantics here are that we are reading from bp/attr and >> >> writing to hw? >> >> >> >> If so would some sprinkling of const on the first two parameters help >> >> make that clearer? >> > >> > I seem to remember there was an issue with that due to the various >> > functions >> > we call that need to be converted to take const as well. I thought I would >> > do it in a seperate series but actually it should be no big deal to do it >> > on this one. >> >> Yeah, that does sometimes snowball out of control. >> >> > Let me try that and respin. >> >> Cool. It would be nice to have, but obviously not crucial. > > So I managed to constify the perf_event_attr parameter but not the struct > perf_event *bp > because the task target is fetched from it on is_compat_bp() on ARM64. I > could constify it > all the way up to test_ti_thread_flag() but the thread info can only be > retrieved through > a call to task_thread_info() and that's where the qualifier control ends. The > const can not > be passed there and we can't afford to constify the function either, I fear, > as it is used > everywhere for any purpose, including thread_info modifications.
Thanks for trying. 1 out of 2 const parameters is better than none :) cheers
