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Date:   Thu, 20 Jul 2023 11:47:21 -0700
From:   Bjorn Andersson <quic_bjorande@quicinc.com>
To:     Chengfeng Ye <dg573847474@gmail.com>
CC:     <agross@kernel.org>, <andersson@kernel.org>,
        <konrad.dybcio@linaro.org>, <lee@kernel.org>,
        <sboyd@codeaurora.org>, <srinivas.kandagatla@linaro.org>,
        <linux-arm-msm@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] mfd: qcom-pm8xxx: Fix potential deadlock on
 &chip->pm_irq_lock
Message-ID: <20230720184721.GC2667611@hu-bjorande-lv.qualcomm.com>
References: <20230720071330.50382-1-dg573847474@gmail.com>
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In-Reply-To: <20230720071330.50382-1-dg573847474@gmail.com>
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On Thu, Jul 20, 2023 at 07:13:30AM +0000, Chengfeng Ye wrote:
> As &chip->pm_irq_lock is acquired by pm8xxx_irq_handler() under irq
> context, other process context code should disable irq before acquiring
> the lock.
> 
> Since .irq_set_type and .irq_get_irqchip_state callbacks are generally
> executed from process context without irq disabled by default, the same
> lock acquision should disable irq.
> 
> Possible deadlock scenario
> pm8xxx_irq_set_type()
>     -> pm8xxx_config_irq()
>     -> spin_lock(&chip->pm_irq_lock)
>         <irq interrupt>
>         -> pm8xxx_irq_handler()
>         -> pm8xxx_irq_master_handler()
>         -> pm8xxx_irq_block_handler()
>         -> pm8xxx_read_block_irq()
>         -> spin_lock(&chip->pm_irq_lock) (deadlock here)
> 
> This flaw was found using an experimental static analysis tool we are
> developing for irq-related deadlock.
> 
> Fix the potential deadlock by spin_lock_irqsave().
> 
> Signed-off-by: Chengfeng Ye <dg573847474@gmail.com>

Reviewed-by: Bjorn Andersson <quic_bjorande@quicinc.com>

Regards,
Bjorn