Re: [PATCH] coresight: etm4x: fix mis-usage of nr_resource in sysfs interface

Mathieu Poirier
2020-09-03T17:24:35Z

On Wed, Sep 02, 2020 at 03:52:56PM +0800, Jonathan Zhou wrote:
> The member @nr_resource represents how many resource selector pairs,
> and the pair 0 is always implemented and reserved.
> So let's multiply by 2 when displaying the implemented resource seletors
> and resetting the seletor configuration .
> And also update the validation of the input @idx.
>
> Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
> Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
> Cc: Mike Leach <mike.leach@linaro.org>
> Cc: Shaokun Zhang <zhangshaokun@hisilicon.com>
> Cc: lizixian@hisilicon.com
> Signed-off-by: Jonathan Zhou <jonathan.zhouwen@huawei.com>
> ---
> drivers/hwtracing/coresight/coresight-etm4x-sysfs.c | 15 ++++++++++-----
> 1 file changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
> index b673e738bc9a..635b93d20efa 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
> +++ b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
> @@ -143,8 +143,10 @@ static ssize_t nr_resource_show(struct device *dev,
> {
> unsigned long val;
> struct etmv4_drvdata *drvdata = dev_get_drvdata(dev->parent);
> -
> - val = drvdata->nr_resource;
> + /* @nr_resource represents how many resource selector pairs,
> + * hence multiply by 2.

Your comment said it correctly, @nr_resource present the number of _pairs_. As
such the code is correct and there is no need to multiply by 2.

> + */
> + val = 2 * drvdata->nr_resource;
> return scnprintf(buf, PAGE_SIZE, "%#lx\n", val);
> }
> static DEVICE_ATTR_RO(nr_resource);
> @@ -236,7 +238,7 @@ static ssize_t reset_store(struct device *dev,
> }
>
> config->res_idx = 0x0;
> - for (i = 0; i < drvdata->nr_resource; i++)
> + for (i = 2; i < 2 * drvdata->nr_resource; i++)
> config->res_ctrl[i] = 0x0;

This hunk is correct - please send a patch for it.

>
> config->ss_idx = 0x0;
> @@ -1663,8 +1665,11 @@ static ssize_t res_idx_store(struct device *dev,
>
> if (kstrtoul(buf, 16, &val))
> return -EINVAL;
> - /* Resource selector pair 0 is always implemented and reserved */
> - if ((val == 0) || (val >= drvdata->nr_resource))
> + /*
> + * Resource selector pair 0 is always implemented and reserved,
> + * namely an idx with 0 and 1 is illegal.
> + */
> + if ((val == 0) || (val == 1) || (val >= 2 * drvdata->nr_resource))
> return -EINVAL;

The index, i.e ->res_idx, represent pairs an not individual resource.

Thanks,
Mathieu

>
> /*
> --
> 1.9.1