linux-kernel - Re: [PATCH v2] nvmem: properly handle returned value nvmem_reg

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Message-ID: <2cb62de4-f8be-e3cf-f415-54de60bb669e@linaro.org>
Date:   Thu, 10 May 2018 10:58:27 +0100
From:   Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To:     Mathieu Malaterre <malat@...ian.org>
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] nvmem: properly handle returned value nvmem_reg_read



On 09/05/18 19:57, Mathieu Malaterre wrote:
> Function nvmem_reg_read can return a non zero value indicating an error.
> This returned value must be read and error propagated to
> nvmem_cell_prepare_write_buffer. Silence the following gcc warning (W=1):
> 
>    drivers/nvmem/core.c:1093:9: warning: variable ‘rc’ set but not used [-Wunused-but-set-variable]
> 
> Signed-off-by: Mathieu Malaterre <malat@...ian.org>
> ---
> v2: prefer ERR_PTR(-EINVAL) over a simple return NULL
> 
>   drivers/nvmem/core.c | 7 +++++++
>   1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
> index b05aa8e81303..f7b6c85cf393 100644
> --- a/drivers/nvmem/core.c
> +++ b/drivers/nvmem/core.c
> @@ -1107,6 +1107,8 @@ static void *nvmem_cell_prepare_write_buffer(struct nvmem_cell *cell,
>   
>   		/* setup the first byte with lsb bits from nvmem */
>   		rc = nvmem_reg_read(nvmem, cell->offset, &v, 1);
> +		if (rc)
> +			goto err;
>   		*b++ |= GENMASK(bit_offset - 1, 0) & v;
>   
>   		/* setup rest of the byte if any */
> @@ -1125,11 +1127,16 @@ static void *nvmem_cell_prepare_write_buffer(struct nvmem_cell *cell,
>   		/* setup the last byte with msb bits from nvmem */
>   		rc = nvmem_reg_read(nvmem,
>   				    cell->offset + cell->bytes - 1, &v, 1);
> +		if (rc)
> +			goto err;
>   		*p |= GENMASK(7, (nbits + bit_offset) % BITS_PER_BYTE) & v;
>   
>   	}
>   
>   	return buf;
> +err:
> +	kfree(buf);
> +	return ERR_PTR(-EINVAL);
You should return ERR_PTR(rc) not EINVAL here.
errors should always propagate to caller!

thanks,
srini
>   }
>   
>   /**
>