From mboxrd@z Thu Jan 1 00:00:00 1970 From: maxime.coquelin@st.com (Maxime Coquelin) Date: Tue, 13 Jan 2015 09:59:23 +0100 Subject: [PATCH] reset: sunxi: fix spinlock initialization In-Reply-To: References: <1420678479-630-1-git-send-email-tyler.baker@linaro.org> <54AFC2A8.1010807@st.com> <54AFE968.4010805@st.com> Message-ID: <54B4DE6B.8020705@st.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Tyler, On 01/10/2015 01:22 AM, Tyler Baker wrote: > On 9 January 2015 at 12:44, Tyler Baker wrote: >> Hi Maxime, >> >> On 9 January 2015 at 06:44, Maxime Coquelin wrote: >>> With Maxime in the To: list. >>> >>> >>> >>> On 01/09/2015 12:59 PM, Maxime Coquelin wrote: >>>> Hi Tyler, Maxime, >>>> >>>> On 01/08/2015 01:54 AM, Tyler Baker wrote: >>>>> Call spin_lock_init() before the spinlocks are used, preventing a lockdep >>>>> splat. >>>>> >>>>> I have been observing lockdep complaining [1] during boot on my a80 >>>>> optimus [2] >>>>> when CONFIG_PROVE_LOCKING has been enabled. This patch resolves the >>>>> splat, >>>>> and has been tested on a few other sunxi platforms without issue. >>>>> >>>>> [1] >>>>> http://storage.kernelci.org/next/next-20150107/arm-multi_v7_defconfig+CONFIG_PROVE_LOCKING=y/lab-tbaker/boot-sun9i-a80-optimus.html >>>>> [2] http://kernelci.org/boot/?a80-optimus >>>>> >>>>> Signed-off-by: Tyler Baker >>>>> --- >>>>> This patch was tested on 3.19.0-rc3 >>>>> >>>>> drivers/reset/reset-sunxi.c | 2 ++ >>>>> 1 file changed, 2 insertions(+) >>>>> >>>>> diff --git a/drivers/reset/reset-sunxi.c b/drivers/reset/reset-sunxi.c >>>>> index eebc52c..e37250c 100644 >>>>> --- a/drivers/reset/reset-sunxi.c >>>>> +++ b/drivers/reset/reset-sunxi.c >>>>> @@ -157,6 +157,8 @@ static int sunxi_reset_probe(struct platform_device >>>>> *pdev) >>>>> if (IS_ERR(data->membase)) >>>>> return PTR_ERR(data->membase); >>>>> + spin_lock_init(&data->lock); >>>>> + >>>> Shouldn't the lock be initialized also in early init function >>>> (sunxi_reset_init) ? >> Thanks for pointing this out. It seems reasonable to me to add this >> for the sun6i platforms that use the early init function. Currently >> trying to track down a sun6i platform so I can run a few locking >> validation tests. > Olof was kind enough to volunteer his sun6i platform (colombus) and > provide the results. The results confirms there is a need to also > initialize the lock in sunxi_reset_init as Maxime C. mentioned. > > DEBUG: sunxi_reset_init() > DEBUG: sunxi_reset_deassert() > INFO: trying to register non-static key. > the code is fine but needs lockdep annotation. > turning off the locking correctness validator. > CPU: 0 PID: 0 Comm: swapper/0 Not tainted 3.19.0-rc3-00039-gccd0de2-dirty #5 > Hardware name: Allwinner sun6i (A31) Family > [] (unwind_backtrace) from [] (show_stack+0x10/0x14) > [] (show_stack) from [] (dump_stack+0x8c/0x9c) > [] (dump_stack) from [] (__lock_acquire+0x1ef4/0x1f00) > [] (__lock_acquire) from [] (lock_acquire+0x6c/0x8c) > [] (lock_acquire) from [] (_raw_spin_lock_irqsave+0x3c/0x50) > [] (_raw_spin_lock_irqsave) from [] > (sunxi_reset_deassert+0x2c/0x88) > [] (sunxi_reset_deassert) from [] > (sun5i_timer_init+0xc0/0x1f0) > [] (sun5i_timer_init) from [] > (clocksource_of_init+0x4c/0x8c) > [] (clocksource_of_init) from [] (start_kernel+0x278/0x3c8) > [] (start_kernel) from [<40208074>] (0x40208074) > > I'll go ahead and resend an updated patch and cc stable if Philipp and > Maxime R. they agree. Thanks for having done the test. I have no Allwinner HW to try. Best regards, Maxime > >>>> Regards, >>>> Maxime >>>>> data->rcdev.owner = THIS_MODULE; >>>>> data->rcdev.nr_resets = resource_size(res) * 32; >>>>> data->rcdev.ops = &sunxi_reset_ops; >>>> >> >> >> -- >> Tyler Baker >> Tech Lead, LAVA >> Linaro.org | Open source software for ARM SoCs >> Follow Linaro: http://www.facebook.com/pages/Linaro >> http://twitter.com/#!/linaroorg - http://www.linaro.org/linaro-blog > Cheers, >