linux-kernel - Re: [PATCH] soc: fsl: qe: Add check for ioremap

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Date:   Sun, 9 Oct 2022 16:32:57 +0000
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Jiasheng Jiang <jiasheng@...as.ac.cn>,
        "qiang.zhao@....com" <qiang.zhao@....com>,
        "leoyang.li@....com" <leoyang.li@....com>
CC:     "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] soc: fsl: qe: Add check for ioremap



Le 08/10/2022 à 04:38, Jiasheng Jiang a écrit :
> As ioremap can return NULL pointer, it should
> be better to check the return value return error
> if fails.
> Moreover, the return value of qe_reset should be
> checked by cascade.
> 
> Fixes: 68f047e3d62e ("fsl/qe: add rx_sync and tx_sync for TDM mode")
> Signed-off-by: Jiasheng Jiang <jiasheng@...as.ac.cn>
> ---
>   drivers/soc/fsl/qe/qe.c | 23 ++++++++++++++++++-----
>   include/soc/fsl/qe/qe.h |  4 ++--
>   2 files changed, 20 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/soc/fsl/qe/qe.c b/drivers/soc/fsl/qe/qe.c
> index b3c226eb5292..88e335e8eef7 100644
> --- a/drivers/soc/fsl/qe/qe.c
> +++ b/drivers/soc/fsl/qe/qe.c
> @@ -83,10 +83,13 @@ static phys_addr_t get_qe_base(void)
>   	return qebase;
>   }
>   
> -void qe_reset(void)
> +int qe_reset(void)
>   {
> -	if (qe_immr == NULL)
> +	if (qe_immr == NULL) {
>   		qe_immr = ioremap(get_qe_base(), QE_IMMAP_SIZE);
> +		if (qe_immr == NULL)
> +			return -ENOMEM;
> +	}

I'd prefer with the following form:

	if (qe_immr == NULL)
		qe_immr = ioremap(get_qe_base(), QE_IMMAP_SIZE);

	if (qe_immr == NULL)
		return -ENOMEM;

>   
>   	qe_snums_init();
>   
> @@ -98,6 +101,8 @@ void qe_reset(void)
>   
>   	if (qe_sdma_init())
>   		panic("sdma init failed!");
> +
> +	return 0;
>   }
>   
>   int qe_issue_cmd(u32 cmd, u32 device, u8 mcn_protocol, u32 cmd_input)
> @@ -640,11 +645,14 @@ EXPORT_SYMBOL(qe_get_num_of_snums);
>   static int __init qe_init(void)
>   {
>   	struct device_node *np;
> +	int ret;
>   
>   	np = of_find_compatible_node(NULL, NULL, "fsl,qe");
>   	if (!np)
>   		return -ENODEV;
> -	qe_reset();
> +	ret = qe_reset();
> +	if (ret)
> +		return ret;

I think that if you return before the of_node_put(), you leak the 
reference taken by of_find_compatible_node()

qe_reset() doesn't use np, so you can likely perform the of_node_put() 
before calling qe_reset(), then you can simply do

	return qe_reset();

>   	of_node_put(np);
>   	return 0;
>   }
> @@ -653,8 +661,13 @@ subsys_initcall(qe_init);
>   #if defined(CONFIG_SUSPEND) && defined(CONFIG_PPC_85xx)
>   static int qe_resume(struct platform_device *ofdev)
>   {
> -	if (!qe_alive_during_sleep())
> -		qe_reset();
> +	int ret;
> +
> +	if (!qe_alive_during_sleep()) {
> +		ret = qe_reset();
> +		if (ret)
> +			return ret;
> +	}

More complicated that needed.

You could simply do:

	if (!qe_alive_during_sleep())
		return qe_reset();


>   	return 0;
>   }
>   
> diff --git a/include/soc/fsl/qe/qe.h b/include/soc/fsl/qe/qe.h
> index b02e9fe69146..71129b8a5807 100644
> --- a/include/soc/fsl/qe/qe.h
> +++ b/include/soc/fsl/qe/qe.h
> @@ -84,9 +84,9 @@ extern spinlock_t cmxgcr_lock;
>   
>   /* Export QE common operations */
>   #ifdef CONFIG_QUICC_ENGINE
> -extern void qe_reset(void);
> +extern int qe_reset(void);

Please taken the opportunity to remove the pointless 'extern' keyword 
when changing such a prototype.

>   #else
> -static inline void qe_reset(void) {}
> +static inline int qe_reset(void) {}

If qe_reset() is not void anymore, it must return something.

>   #endif
>   
>   int cpm_muram_init(void);