On 04/17/13 16:26, Stephen Boyd wrote: > Hot-plugging with CONFIG_DEBUG_PREEMPT=y on a device with arm > architected timers causes a slew of "using smp_processor_id() in > preemptible" warnings: > > BUG: using smp_processor_id() in preemptible [00000000] code: sh/111 > caller is arch_timer_cpu_notify+0x14/0xc8 > > This happens because sometimes the cpu notifier, > arch_timer_cpu_notify(), is called in preemptible context and > other times in non-preemptible context but we use this_cpu_ptr() > to retrieve the clockevent in all cases. We're only going to > actually use the pointer in non-preemptible context though, so > push the this_cpu_ptr() access down into the cases to force the > checks to occur only in non-preemptible contexts. > > Cc: John Stultz <john.stultz@xxxxxxxxxx> > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Cc: Mark Rutland <mark.rutland@xxxxxxx> > Acked-by: Marc Zyngier <Marc.Zyngier@xxxxxxx> > Signed-off-by: Stephen Boyd <sboyd@xxxxxxxxxxxxxx> > --- > > Resending to arm-soc maintainers instead of timekeeping maintainers. Who > maintains this driver? Ping. > > drivers/clocksource/arm_arch_timer.c | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c > index d7ad425..a65a710 100644 > --- a/drivers/clocksource/arm_arch_timer.c > +++ b/drivers/clocksource/arm_arch_timer.c > @@ -248,14 +248,16 @@ static void __cpuinit arch_timer_stop(struct clock_event_device *clk) > static int __cpuinit arch_timer_cpu_notify(struct notifier_block *self, > unsigned long action, void *hcpu) > { > - struct clock_event_device *evt = this_cpu_ptr(arch_timer_evt); > - > + /* > + * Grab cpu pointer in each case to avoid spurious > + * preemptible warnings > + */ > switch (action & ~CPU_TASKS_FROZEN) { > case CPU_STARTING: > - arch_timer_setup(evt); > + arch_timer_setup(this_cpu_ptr(arch_timer_evt)); > break; > case CPU_DYING: > - arch_timer_stop(evt); > + arch_timer_stop(this_cpu_ptr(arch_timer_evt)); > break; > } > -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html