Subject: [PATCH arm 1/1] arm: Use _rcuidle tracepoint to allow use from idle

From: [email-masked] (Tony Lindgren)
Date: Tue, 26 Apr 2016 12:51:59 -0700

* Steven Rostedt <[email-masked]> [160426 12:45]:
> *Whack* *Whack* *Whack*!!!
> 
> Signed-off-by: Steven Rostedt <[email-masked]>
> ---
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index fb74dc1f7520..4fa43c02d682 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -682,12 +682,12 @@ static void clk_core_disable(struct clk_core *core)
>  	if (--core->enable_count > 0)
>  		return;
>  
> -	trace_clk_disable(core);
> +	trace_clk_disable_rcuidle(core);
>  
>  	if (core->ops->disable)
>  		core->ops->disable(core->hw);
>  
> -	trace_clk_disable_complete(core);
> +	trace_clk_disable_complete_rcuidle(core);
>  
>  	clk_core_disable(core->parent);
>  }

Now the mole shows up here!

===============================
[ INFO: suspicious RCU usage. ]
4.6.0-rc5-next-20160426+ #1116 Not tainted
-------------------------------
include/trace/events/rpm.h:95 suspicious rcu_dereference_check() usage!

other info that might help us debug this:

RCU used illegally from idle CPU!
rcu_scheduler_active = 1, debug_locks = 0
RCU used illegally from extended quiescent state!
1 lock held by swapper/0/0:
 #0:  (&(&dev->power.lock)->rlock){-.-...}, at: [<c052cc2c>] __rpm_callback+0x58/0x60

stack backtrace:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.6.0-rc5-next-20160426+ #1116
Hardware name: Generic OMAP36xx (Flattened Device Tree)
[<c0110290>] (unwind_backtrace) from [<c010c3a8>] (show_stack+0x10/0x14)
[<c010c3a8>] (show_stack) from [<c047fd68>] (dump_stack+0xb0/0xe4)
[<c047fd68>] (dump_stack) from [<c052d5d0>] (rpm_suspend+0x580/0x768)
[<c052d5d0>] (rpm_suspend) from [<c052ec58>] (__pm_runtime_suspend+0x64/0x84)
[<c052ec58>] (__pm_runtime_suspend) from [<c04bf25c>] (omap2_gpio_prepare_for_idle+0x5c/0x70)
[<c04bf25c>] (omap2_gpio_prepare_for_idle) from [<c0125568>] (omap_sram_idle+0x140/0x244)
[<c0125568>] (omap_sram_idle) from [<c01269dc>] (omap3_enter_idle_bm+0xfc/0x1ec)
[<c01269dc>] (omap3_enter_idle_bm) from [<c0601bdc>] (cpuidle_enter_state+0x80/0x3d4)
[<c0601bdc>] (cpuidle_enter_state) from [<c0183b08>] (cpu_startup_entry+0x198/0x3a0)
[<c0183b08>] (cpu_startup_entry) from [<c0b00c0c>] (start_kernel+0x354/0x3c8)
[<c0b00c0c>] (start_kernel) from [<8000807c>] (0x8000807c)