[PATCH] nvme-multipath: require exact iopolicy names for module parameter

[John Garry]

On 29/05/2026 09:51, dayou5941 at 163.com wrote:
> From: liyouhong <liyouhong at kylinos.cn>
> 
> The iopolicy module parameter uses strncmp prefix matching, so values
> like "numax" are accepted as "numa".  The per-subsystem sysfs attribute
> already requires an exact match via sysfs_streq().  Parse both through
> a shared helper so invalid values are rejected consistently.
> 
> Signed-off-by: liyouhong <liyouhong at kylinos.cn>

Feel free to ignore my comments below, FWIW:

Reviewed-by: John Garry <john.g.garry at oracle.com>

 > --->   drivers/nvme/host/multipath.c | 40 
+++++++++++++++++++++--------------
>   1 file changed, 24 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
> index 263161cb8ac0..ce8dbb741d57 100644
> --- a/drivers/nvme/host/multipath.c
> +++ b/drivers/nvme/host/multipath.c
> @@ -73,19 +73,29 @@ static const char *nvme_iopolicy_names[] = {
>   
>   static int iopolicy = NVME_IOPOLICY_NUMA;
>   
> +static int nvme_iopolicy_parse(const char *str)
> +{
> +	int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(nvme_iopolicy_names); i++) {
> +		if (sysfs_streq(str, nvme_iopolicy_names[i]))
> +			return i;
> +	}
> +	return -EINVAL;

This is nearly duplicating __sysfs_match_string

BTW, going slightly off topic, I think that nvme_iopolicy_names could be 
made const char *const

> +}
> +
>   static int nvme_set_iopolicy(const char *val, const struct kernel_param *kp)
>   {
> +	int policy;
> +
>   	if (!val)
>   		return -EINVAL;
> -	if (!strncmp(val, "numa", 4))
> -		iopolicy = NVME_IOPOLICY_NUMA;
> -	else if (!strncmp(val, "round-robin", 11))
> -		iopolicy = NVME_IOPOLICY_RR;
> -	else if (!strncmp(val, "queue-depth", 11))
> -		iopolicy = NVME_IOPOLICY_QD;
> -	else
> -		return -EINVAL;
>   
> +	policy = nvme_iopolicy_parse(val);
> +	if (policy < 0)
> +		return policy;
> +
> +	iopolicy = policy;
>   	return 0;
>   }
>   
> @@ -1039,16 +1049,14 @@ static ssize_t nvme_subsys_iopolicy_store(struct device *dev,
>   {
>   	struct nvme_subsystem *subsys =
>   		container_of(dev, struct nvme_subsystem, dev);
> -	int i;
> +	int policy;
>   
> -	for (i = 0; i < ARRAY_SIZE(nvme_iopolicy_names); i++) {
> -		if (sysfs_streq(buf, nvme_iopolicy_names[i])) {
> -			nvme_subsys_iopolicy_update(subsys, i);
> -			return count;
> -		}
> -	}
> +	policy = nvme_iopolicy_parse(buf);
> +	if (policy < 0)
> +		return policy;
>   
> -	return -EINVAL;
> +	nvme_subsys_iopolicy_update(subsys, policy);
> +	return count;
>   }
>   SUBSYS_ATTR_RW(iopolicy, S_IRUGO | S_IWUSR,
>   		      nvme_subsys_iopolicy_show, nvme_subsys_iopolicy_store);