From: Daniel Lezcano <[email protected]> Sent: Monday, March 1, 2021 4:22 AM > > On 01/03/2021 02:15, Michael Kelley wrote: > > While the driver for the Hyper-V Reference TSC and STIMERs is architecture > > neutral, vDSO is implemented for x86/x64, but not for ARM64. Current code > > calls into utility functions under arch/x86 (and coming, under arch/arm64) > > to handle the difference. > > > > Change this approach to handle the difference inline based on whether > > VDSO_CLOCK_MODE_HVCLOCK is present. The new approach removes code under > > arch/* since the difference is tied more to the specifics of the Linux > > implementation than to the architecture. > > > > No functional change. > > A suggestion below > > > > Signed-off-by: Michael Kelley <[email protected]> > > Reviewed-by: Boqun Feng <[email protected]> > > --- > > arch/x86/include/asm/mshyperv.h | 4 ---- > > drivers/clocksource/hyperv_timer.c | 10 ++++++++-- > > 2 files changed, 8 insertions(+), 6 deletions(-) > > > > diff --git a/drivers/clocksource/hyperv_timer.c > > b/drivers/clocksource/hyperv_timer.c > > index c73c127..5e5e08aa 100644 > > --- a/drivers/clocksource/hyperv_timer.c > > +++ b/drivers/clocksource/hyperv_timer.c > > @@ -372,7 +372,9 @@ static void resume_hv_clock_tsc(struct clocksource *arg) > > > > static int hv_cs_enable(struct clocksource *cs) > > static __maybe_unused int hv_cs_enable(struct clocksource *cs) > > > { > > - hv_enable_vdso_clocksource(); > > +#ifdef VDSO_CLOCKMODE_HVCLOCK > > + vclocks_set_used(VDSO_CLOCKMODE_HVCLOCK); > > +#endif > > return 0; > > } > > > > @@ -385,6 +387,11 @@ static int hv_cs_enable(struct clocksource *cs) > > .suspend= suspend_hv_clock_tsc, > > .resume = resume_hv_clock_tsc, > > .enable = hv_cs_enable, > > +#ifdef VDSO_CLOCKMODE_HVCLOCK > > + .vdso_clock_mode = VDSO_CLOCKMODE_HVCLOCK, > > +#else > > + .vdso_clock_mode = VDSO_CLOCKMODE_NONE, > > +#endif > > #ifdef VDSO_CLOCKMODE_HVCLOCK > .enable = hv_cs_enable, > .vdso_clock_mode = VDSO_CLOCKMODE_HVCLOCK, > #else > .vdso_clock_mode = VDSO_CLOCKMODE_NONE, > #endif >
Is there any particular benefit (that I might not be recognizing) to having the .enable function be NULL vs. a function that does nothing? I can see the handful of places where the .enable function is invoked, and there doesn't seem to be much difference. In any case, I have no problem with making the change in a v3 of the patch set. Michael
