Hi Mathieu,
On 11/02/22 00:18, Mathieu Poirier wrote:
> Hi Puranjay,
>
> On Wed, Feb 09, 2022 at 02:33:41PM +0530, 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 '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 deny the sysfs state/firmware/recovery change by
>> introducing a state flag 'deny_sysfs_ops' 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 hide the sysfs
>> state/firmware/recovery entries when deny_sysfs_ops flag is set.
>>
>> Signed-off-by: Puranjay Mohan <p-mohan@xxxxxx>
>> ---
>> 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 | 18 +++++++++++++++++-
>> include/linux/remoteproc.h | 2 ++
>> 2 files changed, 19 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/remoteproc/remoteproc_sysfs.c b/drivers/remoteproc/remoteproc_sysfs.c
>> index ea8b89f97d7b..da2d0eecfa44 100644
>> --- a/drivers/remoteproc/remoteproc_sysfs.c
>> +++ b/drivers/remoteproc/remoteproc_sysfs.c
>> @@ -230,6 +230,21 @@ 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->deny_sysfs_ops && (attr == &dev_attr_recovery.attr ||
>> + attr == &dev_attr_firmware.attr ||
>> + attr == &dev_attr_state.attr))
>
> I was wondering if we should also add coredump to this group to make it an all
> or nothing option (name is already read only).
I have sent a v5 where I have added coredump to this.
>
>> + mode = 0444;
>
> Much better.
>
>> +
>> + return mode;
>> +}
>> +
>> static struct attribute *rproc_attrs[] = {
>> &dev_attr_coredump.attr,
>> &dev_attr_recovery.attr,
>> @@ -240,7 +255,8 @@ 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..3849c66ce38f 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
>> + * @deny_sysfs_ops: flag to not permit sysfs operations on state, firmware and recovery
>> * @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 deny_sysfs_ops;
>
> Wouldn't "sysfs_read_only" make more sense?
I agree, I have renamed it to sysfs_read_only in v5 patch
>
>
> With or without the above and for this set:
>
> Reviewed-by: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
Thanks.
Puranjay Mohan
>
>> struct list_head dump_segments;
>> int nb_vdev;
>> u8 elf_class;
>> --
>> 2.17.1
>>
