Re: [PATCH v2] i2c: bcm-iproc: Fix bcm_iproc_i2c_isr deadlock issue

From: Ray Jui <ray.jui@broadcom.com>
To: Chengfeng Ye <dg573847474@gmail.com>,
	andi.shyti@kernel.org, rjui@broadcom.com, sbranden@broadcom.com,
	wsa@kernel.org
Cc: bcm-kernel-feedback-list@broadcom.com, linux-i2c@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] i2c: bcm-iproc: Fix bcm_iproc_i2c_isr deadlock issue
Date: Fri, 7 Jul 2023 08:50:38 -0700	[thread overview]
Message-ID: <6e6d8cfd-63fd-f3b5-7ab0-a4d99895a17c@broadcom.com> (raw)
In-Reply-To: <20230707084941.28964-1-dg573847474@gmail.com>

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On 7/7/2023 1:49 AM, Chengfeng Ye wrote:
> iproc_i2c_rd_reg() and iproc_i2c_wr_reg() are called from both
> interrupt context (e.g. bcm_iproc_i2c_isr) and process context
> (e.g. bcm_iproc_i2c_suspend). Therefore, interrupts should be
> disabled to avoid potential deadlock. To prevent this scenario,
> use spin_lock_irqsave().
> 
> Fixes: 9a1038728037 ("i2c: iproc: add NIC I2C support")
> Signed-off-by: Chengfeng Ye <dg573847474@gmail.com>
> ---
>  drivers/i2c/busses/i2c-bcm-iproc.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-bcm-iproc.c b/drivers/i2c/busses/i2c-bcm-iproc.c
> index 85d8a6b04885..30a2a3200bed 100644
> --- a/drivers/i2c/busses/i2c-bcm-iproc.c
> +++ b/drivers/i2c/busses/i2c-bcm-iproc.c
> @@ -233,13 +233,14 @@ static inline u32 iproc_i2c_rd_reg(struct bcm_iproc_i2c_dev *iproc_i2c,
>  				   u32 offset)
>  {
>  	u32 val;
> +	unsigned long flags;
>  
>  	if (iproc_i2c->idm_base) {
> -		spin_lock(&iproc_i2c->idm_lock);
> +		spin_lock_irqsave(&iproc_i2c->idm_lock, flags);
>  		writel(iproc_i2c->ape_addr_mask,
>  		       iproc_i2c->idm_base + IDM_CTRL_DIRECT_OFFSET);
>  		val = readl(iproc_i2c->base + offset);
> -		spin_unlock(&iproc_i2c->idm_lock);
> +		spin_unlock_irqrestore(&iproc_i2c->idm_lock, flags);
>  	} else {
>  		val = readl(iproc_i2c->base + offset);
>  	}
> @@ -250,12 +251,14 @@ static inline u32 iproc_i2c_rd_reg(struct bcm_iproc_i2c_dev *iproc_i2c,
>  static inline void iproc_i2c_wr_reg(struct bcm_iproc_i2c_dev *iproc_i2c,
>  				    u32 offset, u32 val)
>  {
> +	unsigned long flags;
> +
>  	if (iproc_i2c->idm_base) {
> -		spin_lock(&iproc_i2c->idm_lock);
> +		spin_lock_irqsave(&iproc_i2c->idm_lock, flags);
>  		writel(iproc_i2c->ape_addr_mask,
>  		       iproc_i2c->idm_base + IDM_CTRL_DIRECT_OFFSET);
>  		writel(val, iproc_i2c->base + offset);
> -		spin_unlock(&iproc_i2c->idm_lock);
> +		spin_unlock_irqrestore(&iproc_i2c->idm_lock, flags);
>  	} else {
>  		writel(val, iproc_i2c->base + offset);
>  	}

Acked-by: Ray Jui <ray.jui@broadcom.com>

Thanks, Chengfeng.

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