On Mon, Sep 07, 2020 at 04:35:40PM +0530, Vaibhav Jain wrote:
> The newly introduced 'perf_stats' attribute uses the default access
> mode of 0444 letting non-root users access performance stats of an
> nvdimm and potentially force the kernel into issuing large number of
> expensive HCALLs. Since the information exposed by this attribute
> cannot be cached hence its better to ward of access to this attribute
^^^
off?
> from users who don't need to access these performance statistics.
>
> Hence this patch updates access mode of 'perf_stats' attribute to
> be only readable by root users.
Generally it is bad form to say "this patch". See 4c here:
-- https://www.ozlabs.org/~akpm/stuff/tpp.txt
But I'm not picky... :-D
With the s/of/off/ change:
Reviewed-by: Ira Weiny <ira.we...@intel.com>
>
> Fixes: 2d02bf835e573 ('powerpc/papr_scm: Fetch nvdimm performance stats from
> PHYP')
> Reported-by: Aneesh Kumar K.V <aneesh.ku...@linux.ibm.com>
> Signed-off-by: Vaibhav Jain <vaib...@linux.ibm.com>
> ---
> Change-log:
>
> v2:
> * Instead of checking for perfmon_capable() inside show_perf_stats()
> set the attribute as DEVICE_ATTR_ADMIN_RO [ Aneesh ]
> * Update patch description
> ---
> arch/powerpc/platforms/pseries/papr_scm.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/platforms/pseries/papr_scm.c
> b/arch/powerpc/platforms/pseries/papr_scm.c
> index f439f0dfea7d1..a88a707a608aa 100644
> --- a/arch/powerpc/platforms/pseries/papr_scm.c
> +++ b/arch/powerpc/platforms/pseries/papr_scm.c
> @@ -822,7 +822,7 @@ static ssize_t perf_stats_show(struct device *dev,
> kfree(stats);
> return rc ? rc : seq_buf_used(&s);
> }
> -DEVICE_ATTR_RO(perf_stats);
> +DEVICE_ATTR_ADMIN_RO(perf_stats);
>
> static ssize_t flags_show(struct device *dev,
> struct device_attribute *attr, char *buf)
> --
> 2.26.2
>
