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.
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;
>>>
