Messages in this thread | | | Subject | Re: [PATCH RESEND] arm64: arch_timer: fix the infinite recursion when enable ftrace and erratum workaround | From | Hanjun Guo <> | Date | Mon, 10 Jul 2017 14:12:29 +0800 |
| |
On 2017/7/9 16:30, Ding Tianhong wrote: > When enable preempt and debug ftrace, and perform the following steps, the > system will hang: > mount -t debugfs nodev /sys/kernel/debug/ > cd /sys/kernel/debug/tracing/ > echo function_graph > current_tracer > > This is because tracing the preempt_disable/enable calls would cause > trace_clock() which would get local timer to go into infinite recursion > when enable the arch timer erratum workaround for some chips, so Prevent > tracing of preempt_disable/enable() in arch_timer_reg_read_stable(). > > This problem is similar to the fixed by upstream commit 96b3d28bf4 > ("sched/clock: Prevent tracing recursion in sched_clock_cpu()"). > > Fixes: 6acc71ccac71 ("arm64: arch_timer: Allows a CPU-specific erratum to only affect a subset of CPUs") > Signed-off-by: Ding Tianhong <dingtianhong@huawei.com> > --- > arch/arm64/include/asm/arch_timer.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/include/asm/arch_timer.h b/arch/arm64/include/asm/arch_timer.h > index 74d08e4..67bb7a4 100644 > --- a/arch/arm64/include/asm/arch_timer.h > +++ b/arch/arm64/include/asm/arch_timer.h > @@ -65,13 +65,13 @@ struct arch_timer_erratum_workaround { > u64 _val; \ > if (needs_unstable_timer_counter_workaround()) { \ > const struct arch_timer_erratum_workaround *wa; \ > - preempt_disable(); \ > + preempt_disable_notrace(); \ > wa = __this_cpu_read(timer_unstable_counter_workaround); \ > if (wa && wa->read_##reg) \ > _val = wa->read_##reg(); \ > else \ > _val = read_sysreg(reg); \ > - preempt_enable(); \ > + preempt_enable_notrace(); \ > } else { \ > _val = read_sysreg(reg); \ > } \
This fixes my system hang issue when I using function tracer with enabled timer errata on D03,
Tested-by: Hanjun Guo <hanjun.guo@linaro.org>
Thanks Hanjun
| |