On Thu, Mar 03, 2022 at 01:30:08PM +0530, Puranjay Mohan wrote:
> Hi Bjorn,
> Hi Mathieu,
>
> When is this series expected to be applied?
>
> I am going to post another series titled "PRU Consumer API".
> One patch from that series depends on this "Introduce sysfs_read_only
> flag" patch.
>
> Please let me know so I can rebase and post that series.
Applied and pushed.
Thanks,
Mathieu
>
> Thanks,
> Puranjay Mohan
>
> On 18/02/22 11:24, Bjorn Andersson wrote:
> > On Thu 17 Feb 21:00 PST 2022, Kishon Vijay Abraham I wrote:
> >
> >>
> >>
> >> On 16/02/22 1:42 pm, Puranjay Mohan wrote:
> >>> The remoteproc framework provides sysfs interfaces for changing
> >>> the firmware name and for starting/stopping a remote processor
> >>> through the sysfs files 'state' and 'firmware'. The 'coredump'
> >>> file is used to set the coredump configuration. The 'recovery'
> >>> sysfs file can also be used similarly to control the error recovery
> >>> state machine of a remoteproc. These interfaces are currently
> >>> allowed irrespective of how the remoteprocs were booted (like
> >>> remoteproc self auto-boot, remoteproc client-driven boot etc).
> >>> These interfaces can adversely affect a remoteproc and its clients
> >>> especially when a remoteproc is being controlled by a remoteproc
> >>> client driver(s). Also, not all remoteproc drivers may want to
> >>> support the sysfs interfaces by default.
> >>>
> >>> Add support to make the remoteproc sysfs files read only by
> >>> introducing a state flag 'sysfs_read_only' that the individual
> >>> remoteproc drivers can set based on their usage needs. The default
> >>> behavior is to allow the sysfs operations as before.
> >>>
> >>> Implement attribute_group->is_visible() to make the sysfs
> >>> entries read only when 'sysfs_read_only' flag is set.
> >>>
> >>> Signed-off-by: Puranjay Mohan <p-mohan@xxxxxx>
> >>> Reviewed-by: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
> >>> ---
> >>> Changes in v4->v5:
> >>> Rename deny_sysfs_ops to sysfs_read_only.
> >>> Make coredump readonly with other files.
> >>>
> >>> Changes in v3->v4:
> >>> Use mode = 0444 in rproc_is_visible() to make the sysfs entries
> >>> read-only when the deny_sysfs_ops flag is set.
> >>> ---
> >>> drivers/remoteproc/remoteproc_sysfs.c | 19 ++++++++++++++++++-
> >>> include/linux/remoteproc.h | 2 ++
> >>> 2 files changed, 20 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/drivers/remoteproc/remoteproc_sysfs.c b/drivers/remoteproc/remoteproc_sysfs.c
> >>> index ea8b89f97d7b..abf0cd05d5e1 100644
> >>> --- a/drivers/remoteproc/remoteproc_sysfs.c
> >>> +++ b/drivers/remoteproc/remoteproc_sysfs.c
> >>> @@ -230,6 +230,22 @@ static ssize_t name_show(struct device *dev, struct device_attribute *attr,
> >>> }
> >>> static DEVICE_ATTR_RO(name);
> >>>
> >>> +static umode_t rproc_is_visible(struct kobject *kobj, struct attribute *attr,
> >>> + int n)
> >>> +{
> >>> + struct device *dev = kobj_to_dev(kobj);
> >>> + struct rproc *rproc = to_rproc(dev);
> >>> + umode_t mode = attr->mode;
> >>> +
> >>> + if (rproc->sysfs_read_only && (attr == &dev_attr_recovery.attr ||
> >>> + attr == &dev_attr_firmware.attr ||
> >>> + attr == &dev_attr_state.attr ||
> >>> + attr == &dev_attr_coredump.attr))
> >>> + mode = 0444;
> >>
> >> Nitpick: use S_IRUGO instead of 0444.
> >>
> >
> > Thanks for the suggestion Kishon, but I like 0444, it has direct meaning
> > to me.
> >
> > So unless there's some directive to use S_I*** throughout the kernel I
> > would prefer this.
> >
> > Regards,
> > Bjorn
> >
> >> Thanks,
> >> Kishon
> >>> +
> >>> + return mode;
> >>> +}
> >>> +
> >>> static struct attribute *rproc_attrs[] = {
> >>> &dev_attr_coredump.attr,
> >>> &dev_attr_recovery.attr,
> >>> @@ -240,7 +256,8 @@ static struct attribute *rproc_attrs[] = {
> >>> };
> >>>
> >>> static const struct attribute_group rproc_devgroup = {
> >>> - .attrs = rproc_attrs
> >>> + .attrs = rproc_attrs,
> >>> + .is_visible = rproc_is_visible,
> >>> };
> >>>
> >>> static const struct attribute_group *rproc_devgroups[] = {
> >>> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
> >>> index e0600e1e5c17..93a1d0050fbc 100644
> >>> --- a/include/linux/remoteproc.h
> >>> +++ b/include/linux/remoteproc.h
> >>> @@ -523,6 +523,7 @@ struct rproc_dump_segment {
> >>> * @table_sz: size of @cached_table
> >>> * @has_iommu: flag to indicate if remote processor is behind an MMU
> >>> * @auto_boot: flag to indicate if remote processor should be auto-started
> >>> + * @sysfs_read_only: flag to make remoteproc sysfs files read only
> >>> * @dump_segments: list of segments in the firmware
> >>> * @nb_vdev: number of vdev currently handled by rproc
> >>> * @elf_class: firmware ELF class
> >>> @@ -562,6 +563,7 @@ struct rproc {
> >>> size_t table_sz;
> >>> bool has_iommu;
> >>> bool auto_boot;
> >>> + bool sysfs_read_only;
> >>> struct list_head dump_segments;
> >>> int nb_vdev;
> >>> u8 elf_class;
> >>>
