Re: [Linux-kernel-mentees] [PATCH v2 2/3] PCI: sysfs: Change permissions from symbolic to octal

From: Don Dutile
Date: Wed Sep 04 2019 - 11:32:18 EST


On 09/04/2019 02:22 AM, Kelsey Skunberg wrote:
On Thu, Aug 15, 2019 at 10:37:13AM -0400, Don Dutile wrote:
On 08/14/2019 01:38 AM, Bjorn Helgaas wrote:
[+cc Bodong, Don, Greg for permission question]

On Tue, Aug 13, 2019 at 02:45:12PM -0600, Kelsey Skunberg wrote:
Symbolic permissions such as "(S_IWUSR | S_IWGRP)" are not
preferred and octal permissions should be used instead. Change all
symbolic permissions to octal permissions.

Example of old:

"(S_IWUSR | S_IWGRP)"

Example of new:

"0220"


static DEVICE_ATTR_RO(sriov_totalvfs);
-static DEVICE_ATTR(sriov_numvfs, (S_IRUGO | S_IWUSR | S_IWGRP),
- sriov_numvfs_show, sriov_numvfs_store);
+static DEVICE_ATTR(sriov_numvfs, 0664, sriov_numvfs_show, sriov_numvfs_store);
static DEVICE_ATTR_RO(sriov_offset);
static DEVICE_ATTR_RO(sriov_stride);
static DEVICE_ATTR_RO(sriov_vf_device);
-static DEVICE_ATTR(sriov_drivers_autoprobe, (S_IRUGO | S_IWUSR | S_IWGRP),
- sriov_drivers_autoprobe_show, sriov_drivers_autoprobe_store);
+static DEVICE_ATTR(sriov_drivers_autoprobe, 0664, sriov_drivers_autoprobe_show,
+ sriov_drivers_autoprobe_store);

Greg noticed that sriov_numvfs and sriov_drivers_autoprobe have
"unusual" permissions. These were added by:

0e7df22401a3 ("PCI: Add sysfs sriov_drivers_autoprobe to control VF driver binding")
1789382a72a5 ("PCI: SRIOV control and status via sysfs")

Kelsey's patch correctly preserves the existing permissions, but we
should double-check that they are the permissions they want, and
possibly add a comment about why they're different from the rest.

Bjorn


Hi Don,

The rest being? ... 0644 vs 0664 ?
The file is read & written, thus the (first) 6; I'll have to dig through very old (7 yr) notes to see if the second 6 is needed for libvirt (so it doesn't have to be root to enable).

-dd


Were you able to see if the unusual permissions (0664) are needed for
libvirt? I appreciate your help!

-Kelsey

Asking libvirt team in RH; will get back as soon as I hear back.
LPC time sink may delay the response.

-dd