Re: [PATCH] clocksource/arm_arch_timer: mark arch_timer_read_counter() as notrace to avoid deadloop

From: Marc Zyngier
Date: Tue Jun 11 2019 - 11:30:00 EST

Hi Wei,

On 11/06/2019 16:21, Wei Li wrote:
> According to arch_counter_register(), mark arch_counter_get_*() what
> arch_timer_read_counter() can be as notrace to avoid deadloop when using
> function_graph tracer.
> 0xffff80028af23250 0xffff000010195e00 sched_clock+64
> 0xffff80028af23290 0xffff0000101e83ec trace_clock_local+12
> 0xffff80028af232a0 0xffff00001020e52c function_graph_enter+116
> 0xffff80028af23300 0xffff00001009af9c prepare_ftrace_return+44
> 0xffff80028af23320 0xffff00001009b0a8 ftrace_graph_caller+28
> 0xffff80028af23330 0xffff000010b01918 arch_counter_get_cntvct+16
> 0xffff80028af23340 0xffff000010195e00 sched_clock+64
> 0xffff80028af23380 0xffff0000101e83ec trace_clock_local+12
> 0xffff80028af23390 0xffff00001020e52c function_graph_enter+116
> 0xffff80028af233f0 0xffff00001009af9c prepare_ftrace_return+44
> 0xffff80028af23410 0xffff00001009b0a8 ftrace_graph_caller+28
> 0xffff80028af23420 0xffff000010b01918 arch_counter_get_cntvct+16
> ...
> Fixes: 0ea415390cd3 ("clocksource/arm_arch_timer: Use arch_timer_read_counter to access stable counters")
> Signed-off-by: Wei Li <liwei391@xxxxxxxxxx>

There is already a patch[1] queued for that. Hopefully Daniel
and Thomas will get this into mainline shortly.



Jazz is not dead. It just smells funny...