Re: [PATCH] scsi: ufs: core: sysfs: Prevent div by zero

[Bart Van Assche <bvanassche@acm.org>]

On 11/19/24 10:25 PM, Gwendal Grignou wrote:
> Prevent a division by 0 when monitoring is not enabled.
> 
> Fixes: 1d8613a23f3c ("scsi: ufs: core: Introduce HBA performance monitor sysfs nodes")
> 
> Cc: stable@vger.kernel.org
> Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
> ---
>   drivers/ufs/core/ufs-sysfs.c | 6 ++++++
>   1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/ufs/core/ufs-sysfs.c b/drivers/ufs/core/ufs-sysfs.c
> index c95906443d5f9..3692b39b35e78 100644
> --- a/drivers/ufs/core/ufs-sysfs.c
> +++ b/drivers/ufs/core/ufs-sysfs.c
> @@ -485,6 +485,9 @@ static ssize_t read_req_latency_avg_show(struct device *dev,
>   	struct ufs_hba *hba = dev_get_drvdata(dev);
>   	struct ufs_hba_monitor *m = &hba->monitor;
>   
> +	if (!m->nr_req[READ])
> +		return sysfs_emit(buf, "0\n");
> +
>   	return sysfs_emit(buf, "%llu\n", div_u64(ktime_to_us(m->lat_sum[READ]),
>   						 m->nr_req[READ]));
>   }
> @@ -552,6 +555,9 @@ static ssize_t write_req_latency_avg_show(struct device *dev,
>   	struct ufs_hba *hba = dev_get_drvdata(dev);
>   	struct ufs_hba_monitor *m = &hba->monitor;
>   
> +	if (!m->nr_req[WRITE])
> +		return sysfs_emit(buf, "0\n");
> +
>   	return sysfs_emit(buf, "%llu\n", div_u64(ktime_to_us(m->lat_sum[WRITE]),
>   						 m->nr_req[WRITE]));
>   }

Is anyone using the UFS monitor infrastructure or can it perhaps be
removed?

Thanks,

Bart.