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

From: [email-masked] (Tony Lindgren)
Date: Tue, 26 Apr 2016 12:39:50 -0700

* Paul E. McKenney <[email-masked]> [160426 12:08]:
> On Tue, Apr 26, 2016 at 11:29:39AM -0700, Tony Lindgren wrote:
> > * Paul E. McKenney <[email-masked]> [160426 10:53]:
> > > Does the following patch help?
> > 
> > It just changes the output.. See below.
> 
> Ah -- you need both patches.

Oops sorry, I though I had the first one already from next..

> These are on -rcu at:
> 
> 501889db6fee (arm: Use _rcuidle tracepoint to allow use from idle)
> 99cd56ad86d2 (rm: Use more _rcuidle tracepoints to allow use from idle)

With these omap4 is now OK. But omap3 produces yet another warning,
See below :)

Regards,

Tony

8< ------------------
===============================
[ INFO: suspicious RCU usage. ]
4.6.0-rc5-next-20160426+ #1114 Not tainted
-------------------------------
include/trace/events/clk.h:59 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!
2 locks held by swapper/0/0:
 #0:  (&oh->hwmod_key#30){......}, at: [<c0121b40>] omap_hwmod_idle+0x18/0x44
 #1:  (enable_lock){......}, at: [<c0630998>] clk_enable_lock+0x18/0x124

stack backtrace:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.6.0-rc5-next-20160426+ #1114
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 [<c0631618>] (clk_core_disable+0x17c/0x348)
[<c0631618>] (clk_core_disable) from [<c0632774>] (clk_disable+0x24/0x30)
[<c0632774>] (clk_disable) from [<c0120590>] (_disable_clocks+0x18/0x7c)
[<c0120590>] (_disable_clocks) from [<c0121680>] (_idle+0x12c/0x230)
[<c0121680>] (_idle) from [<c0121b4c>] (omap_hwmod_idle+0x24/0x44)
[<c0121b4c>] (omap_hwmod_idle) from [<c0122c24>] (omap_device_idle+0x3c/0x90)
[<c0122c24>] (omap_device_idle) from [<c052cc00>] (__rpm_callback+0x2c/0x60)
[<c052cc00>] (__rpm_callback) from [<c052cc54>] (rpm_callback+0x20/0x80)
[<c052cc54>] (rpm_callback) from [<c052d150>] (rpm_suspend+0x100/0x768)
[<c052d150>] (rpm_suspend) from [<c052ec58>] (__pm_runtime_suspend+0x64/0x84)
[<c052ec58>] (__pm_runtime_suspend) from [<c04bf25c>] (omap2_gpio_prepare_for_idle+0x5
c/0x70)
[<c04bf25c>] (omap2_gpio_prepare_for_idle) from [<c0125568>] (omap_sram_idle+0x140/0x2
44)
[<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)