linux-kernel - Re: [PATCH arm 1/1] arm: Use _rcuidle tracepoint to allow use from idle

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Message-ID: <20160426203652.GQ3715@linux.vnet.ibm.com>
Date:	Tue, 26 Apr 2016 13:36:52 -0700
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	Tony Lindgren <tony@...mide.com>, linux-kernel@...r.kernel.org,
	mingo@...nel.org, Russell King <linux@....linux.org.uk>,
	linux-omap@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH arm 1/1] arm: Use _rcuidle tracepoint to allow use from
 idle

On Tue, Apr 26, 2016 at 04:16:21PM -0400, Steven Rostedt wrote:
> On Tue, 26 Apr 2016 13:06:13 -0700
> "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com> wrote:
> 
> > On Tue, Apr 26, 2016 at 12:51:59PM -0700, Tony Lindgren wrote:
> > > * Steven Rostedt <rostedt@...dmis.org> [160426 12:45]:  
> > > > *Whack* *Whack* *Whack*!!!
> > > > 
> > > > Signed-off-by: Steven Rostedt <rostedt@...dmis.org>
> > > > ---
> > > > 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!  
> > 
> > And the patch shows up here!
> > 
> > 							Thanx, Paul
> > 
> > ------------------------------------------------------------------------
> > 
> > commit d824fb6beb6e23ade51806e11a882528dc15ae98
> > Author: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
> > Date:   Tue Apr 26 13:03:51 2016 -0700
> > 
> >     arm: Whack another event-trace-from-idle mole
> >     
> >     This commit appends a few _rcuidle suffixes to fix the following
> >     RCU-used-from-idle bug:
> >     
> >     > ===============================
> >     > [ 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)  
> >     
> >     In the immortal words of Steven Rostedt, "*Whack* *Whack* *Whack*!!!"
> 
> WhACKED-by: Steven Rostedt <rostedt@...dmis.org>

I whacked in your WhACKED-by.

							Thanx, Paul