Re: [PATCH v3 1/2] remoteproc: Add a sysfs interface for firmware and state

From: Wendy Liang
Date: Mon Nov 07 2016 - 13:15:47 EST

Hi Matt,

On Fri, Nov 4, 2016 at 2:13 AM, Matt Redfearn <matt.redfearn@xxxxxxxxxx> wrote:
> Hi Wendy,
>
> Replies inline
>
>
>
> On 03/11/16 23:40, Wendy Liang wrote:
>>
>> HI Matt,
>>
>> Thanks for your patch. I am trying it.
>>
>> Please see my questions inline.
>>
>> Thanks,
>> Wendy
>>
>> On Wed, Oct 19, 2016 at 5:05 AM, Matt Redfearn <matt.redfearn@xxxxxxxxxx>
>> wrote:
>>>
>>> This patch adds a sysfs interface to rproc allowing the firmware name
>>> and processor state to be changed dynamically.
>>>
>>> State was previously available in debugfs, and is replicated here. The
>>> firmware file allows retrieval of the running firmware name, and a new
>>> one to be specified at run time, so long as the remote processor has
>>> been stopped.
>>>
>>> Signed-off-by: Matt Redfearn <matt.redfearn@xxxxxxxxxx>
>>>
>>> ---
>>>
>>> Changes in v3:
>>> Drop call to rproc_add_virtio_devices from sysfs firmware_store
>>> Use strcspn to find firmware name length
>>> Explicit indexes for state strings
>>>
>>> Changes in v2:
>>> Have firmware_store perform the necessary steps inline.
>>> Use sysfs_streq when dealing with writes to sysfs files
>>>
>>> Documentation/ABI/testing/sysfs-class-remoteproc | 50 ++++++++
>>> drivers/remoteproc/Makefile | 1 +
>>> drivers/remoteproc/remoteproc_core.c | 3 +
>>> drivers/remoteproc/remoteproc_internal.h | 5 +
>>> drivers/remoteproc/remoteproc_sysfs.c | 151
>>> +++++++++++++++++++++++
>>> 5 files changed, 210 insertions(+)
>>> create mode 100644 Documentation/ABI/testing/sysfs-class-remoteproc
>>> create mode 100644 drivers/remoteproc/remoteproc_sysfs.c
>>>
>>> diff --git a/Documentation/ABI/testing/sysfs-class-remoteproc
>>> b/Documentation/ABI/testing/sysfs-class-remoteproc
>>> new file mode 100644
>>> index 000000000000..d188afebc8ba
>>> --- /dev/null
>>> +++ b/Documentation/ABI/testing/sysfs-class-remoteproc
>>> @@ -0,0 +1,50 @@
>>> +What: /sys/class/remoteproc/.../firmware
>>> +Date: October 2016
>>> +Contact: Matt Redfearn <matt.redfearn@xxxxxxxxxx>
>>> +Description: Remote processor firmware
>>> +
>>> + Reports the name of the firmware currently loaded to the
>>> + remote processor.
>>> +
>>> + To change the running firmware, ensure the remote
>>> processor is
>>> + stopped (using /sys/class/remoteproc/.../state) and write
>>> a new filename.
>>> +
>>> +What: /sys/class/remoteproc/.../state
>>> +Date: October 2016
>>> +Contact: Matt Redfearn <matt.redfearn@xxxxxxxxxx>
>>> +Description: Remote processor state
>>> +
>>> + Reports the state of the remote processor, which will be
>>> one of:
>>> +
>>> + "offline"
>>> + "suspended"
>>> + "running"
>>> + "crashed"
>>> + "invalid"
>>> +
>>> + "offline" means the remote processor is powered off.
>>> +
>>> + "suspended" means that the remote processor is suspended
>>> and
>>> + must be woken to receive messages.
>>> +
>>> + "running" is the normal state of an available remote
>>> processor
>>> +
>>> + "crashed" indicates that a problem/crash has been
>>> detected on
>>> + the remote processor.
>>> +
>>> + "invalid" is returned if the remote processor is in an
>>> + unknown state.
>>> +
>>> + Writing this file controls the state of the remote
>>> processor.
>>> + The following states can be written:
>>> +
>>> + "start"
>>> + "stop"
>>> +
>>> + Writing "start" will attempt to start the processor
>>> running the
>>> + firmware indicated by, or written to,
>>> + /sys/class/remoteproc/.../firmware. The remote processor
>>> should
>>> + transition to "running" state.
>>> +
>>> + Writing "stop" will attempt to halt the remote processor
>>> and
>>> + return it to the "offline" state.
>>> diff --git a/drivers/remoteproc/Makefile b/drivers/remoteproc/Makefile
>>> index 6dfb62ed643f..6da9b12f9798 100644
>>> --- a/drivers/remoteproc/Makefile
>>> +++ b/drivers/remoteproc/Makefile
>>> @@ -5,6 +5,7 @@
>>> obj-$(CONFIG_REMOTEPROC) += remoteproc.o
>>> remoteproc-y := remoteproc_core.o
>>> remoteproc-y += remoteproc_debugfs.o
>>> +remoteproc-y += remoteproc_sysfs.o
>>> remoteproc-y += remoteproc_virtio.o
>>> remoteproc-y += remoteproc_elf_loader.o
>>> obj-$(CONFIG_OMAP_REMOTEPROC) += omap_remoteproc.o
>>> diff --git a/drivers/remoteproc/remoteproc_core.c
>>> b/drivers/remoteproc/remoteproc_core.c
>>> index ccc2a73e94dd..b1860949d106 100644
>>> --- a/drivers/remoteproc/remoteproc_core.c
>>> +++ b/drivers/remoteproc/remoteproc_core.c
>>> @@ -1347,6 +1347,7 @@ struct rproc *rproc_alloc(struct device *dev, const
>>> char *name,
>>> device_initialize(&rproc->dev);
>>> rproc->dev.parent = dev;
>>> rproc->dev.type = &rproc_type;
>>> + rproc->dev.class = &rproc_class;
>>>
>>> /* Assign a unique device index and name */
>>> rproc->index = ida_simple_get(&rproc_dev_index, 0, 0,
>>> GFP_KERNEL);
>>> @@ -1485,6 +1486,7 @@ EXPORT_SYMBOL(rproc_report_crash);
>>>
>>> static int __init remoteproc_init(void)
>>> {
>>> + rproc_init_sysfs();
>>> rproc_init_debugfs();
>>>
>>> return 0;
>>> @@ -1496,6 +1498,7 @@ static void __exit remoteproc_exit(void)
>>> ida_destroy(&rproc_dev_index);
>>>
>>> rproc_exit_debugfs();
>>> + rproc_exit_sysfs();
>>> }
>>> module_exit(remoteproc_exit);
>>>
>>> diff --git a/drivers/remoteproc/remoteproc_internal.h
>>> b/drivers/remoteproc/remoteproc_internal.h
>>> index 4cf93ca2816e..c2c3e4762b90 100644
>>> --- a/drivers/remoteproc/remoteproc_internal.h
>>> +++ b/drivers/remoteproc/remoteproc_internal.h
>>> @@ -63,6 +63,11 @@ void rproc_create_debug_dir(struct rproc *rproc);
>>> void rproc_init_debugfs(void);
>>> void rproc_exit_debugfs(void);
>>>
>>> +/* from remoteproc_sysfs.c */
>>> +extern struct class rproc_class;
>>> +int rproc_init_sysfs(void);
>>> +void rproc_exit_sysfs(void);
>>> +
>>> void rproc_free_vring(struct rproc_vring *rvring);
>>> int rproc_alloc_vring(struct rproc_vdev *rvdev, int i);
>>>
>>> diff --git a/drivers/remoteproc/remoteproc_sysfs.c
>>> b/drivers/remoteproc/remoteproc_sysfs.c
>>> new file mode 100644
>>> index 000000000000..bc5b0e00efb1
>>> --- /dev/null
>>> +++ b/drivers/remoteproc/remoteproc_sysfs.c
>>> @@ -0,0 +1,151 @@
>>> +/*
>>> + * Remote Processor Framework
>>> + *
>>> + * This program is free software; you can redistribute it and/or
>>> + * modify it under the terms of the GNU General Public License
>>> + * version 2 as published by the Free Software Foundation.
>>> + *
>>> + * This program is distributed in the hope that it will be useful,
>>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
>>> + * GNU General Public License for more details.
>>> + */
>>> +
>>> +#include <linux/remoteproc.h>
>>> +
>>> +#include "remoteproc_internal.h"
>>> +
>>> +#define to_rproc(d) container_of(d, struct rproc, dev)
>>> +
>>> +/* Expose the loaded / running firmware name via sysfs */
>>> +static ssize_t firmware_show(struct device *dev, struct device_attribute
>>> *attr,
>>> + char *buf)
>>> +{
>>> + struct rproc *rproc = to_rproc(dev);
>>> +
>>> + return sprintf(buf, "%s\n", rproc->firmware);
>>> +}
>>> +
>>> +/* Change firmware name via sysfs */
>>> +static ssize_t firmware_store(struct device *dev,
>>> + struct device_attribute *attr,
>>> + const char *buf, size_t count)
>>> +{
>>> + struct rproc *rproc = to_rproc(dev);
>>> + char *p;
>>> + int err, len = count;
>>> +
>>> + err = mutex_lock_interruptible(&rproc->lock);
>>> + if (err) {
>>> + dev_err(dev, "can't lock rproc %s: %d\n", rproc->name,
>>> err);
>>> + return -EINVAL;
>>> + }
>>> +
>>> + if (rproc->state != RPROC_OFFLINE) {
>>> + dev_err(dev, "can't change firmware while running\n");
>>> + err = -EBUSY;
>>> + goto out;
>>> + }
>>> +
>>> + len = strcspn(buf, "\n");
>>> +
>>> + p = kstrndup(buf, len, GFP_KERNEL);
>>> + if (!p) {
>>> + err = -ENOMEM;
>>> + goto out;
>>> + }
>>> +
>>> + kfree(rproc->firmware);
>>
>> it gives me kernel panic if the initial firmware name is passed from
>> my remoteproc driver to rproc_alloc()
>> and it is a const string.
>> It is better to have another modification to the remoteproc_core.c as
>> follows in the rproc_alloc().
>>
>> - if (!firmware)
>> + if (!firmware) {
>> /*
>> * Make room for default firmware name (minus %s plus
>> '\0').
>> * If the caller didn't pass in a firmware name then
>> @@ -1332,17 +1346,29 @@ struct rproc *rproc_alloc(struct device *dev,
>> const char *name,
>> * the caller doesn't pass one).
>> */
>> name_len = strlen(name) + strlen(template) - 2 + 1;
>> + p = kmalloc_track_caller(name_len, GFP_KERNEL);
>> + if (!p)
>> + return NULL;
>> + snprintf(p, name_len, template, name);
>> + } else {
>> + p = kstrndup(firmware, strlen(firmware), GFP_KERNEL);
>> + if (!p) {
>> + return NULL;
>> + }
>> + }
>>
>> - rproc = kzalloc(sizeof(*rproc) + len + name_len, GFP_KERNEL);
>> + rproc = kzalloc(sizeof(*rproc) + len, GFP_KERNEL);
>
>
> Yes - to address this a very similar change was already introduced into
> Bjorn's tree in
> https://github.com/andersson/remoteproc/commit/0f57dc6ae1ff0c702450083176b657ba37c07363
Great. I didn't know that.

>
>
>
>>
>>> + rproc->firmware = p;
>>> +out:
>>> + mutex_unlock(&rproc->lock);
>>> +
>>> + return err ? err : count;
>>> +}
>>> +static DEVICE_ATTR_RW(firmware);
>>> +
>>> +/*
>>> + * A state-to-string lookup table, for exposing a human readable state
>>> + * via sysfs. Always keep in sync with enum rproc_state
>>> + */
>>> +static const char * const rproc_state_string[] = {
>>> + [RPROC_OFFLINE] = "offline",
>>> + [RPROC_SUSPENDED] = "suspended",
>>> + [RPROC_RUNNING] = "running",
>>> + [RPROC_CRASHED] = "crashed",
>>> + [RPROC_LAST] = "invalid",
>>> +};
>>> +
>>> +/* Expose the state of the remote processor via sysfs */
>>> +static ssize_t state_show(struct device *dev, struct device_attribute
>>> *attr,
>>> + char *buf)
>>> +{
>>> + struct rproc *rproc = to_rproc(dev);
>>> + unsigned int state;
>>> +
>>> + state = rproc->state > RPROC_LAST ? RPROC_LAST : rproc->state;
>>> + return sprintf(buf, "%s\n", rproc_state_string[state]);
>>> +}
>>> +
>>> +/* Change remote processor state via sysfs */
>>> +static ssize_t state_store(struct device *dev,
>>> + struct device_attribute *attr,
>>> + const char *buf, size_t count)
>>> +{
>>> + struct rproc *rproc = to_rproc(dev);
>>> + int ret = 0;
>>> +
>>> + if (sysfs_streq(buf, "start")) {
>>> + if (rproc->state == RPROC_RUNNING)
>>> + return -EBUSY;
>>> +
>>> + ret = rproc_boot(rproc);
>>> + if (ret)
>>> + dev_err(&rproc->dev, "Boot failed: %d\n", ret);
>>> + } else if (sysfs_streq(buf, "stop")) {
>>> + if (rproc->state != RPROC_RUNNING)
>>> + return -EINVAL;
>>> +
>>> + rproc_shutdown(rproc);
>>
>> The kernel hanged when it was trying to unregister the virtio device
>> after I tried"stop".
>> It doesn't look like related to this sysfs API. But just wonder have you
>> seen
>> similar issue?
>
>
> I have not seen that in my testing - but I did run into things such as
> virtio_console giving warnings when the device was removed from a remoteproc
> device (which I submitted a fix for). I guess that the removal of remoteproc
> devices at runtime has previously not been as easy and therefore not as well
> tested so there may well be a few issues lurking as new code paths are
> tested, depending on which virtio devices your firmware implements.
It is just a vring deivce, I am still checking why it hanged at
device_unregister() in the unregister_virtio_device().

>
> Thanks,
> Matt
>
>
>>
>>> + } else {
>>> + dev_err(&rproc->dev, "Unrecognised option: %s\n", buf);
>>> + ret = -EINVAL;
>>> + }
>>> + return ret ? ret : count;
>>> +}
>>> +static DEVICE_ATTR_RW(state);
>>> +
>>> +static struct attribute *rproc_attrs[] = {
>>> + &dev_attr_firmware.attr,
>>> + &dev_attr_state.attr,
>>> + NULL
>>> +};
>>> +
>>> +static const struct attribute_group rproc_devgroup = {
>>> + .attrs = rproc_attrs
>>> +};
>>> +
>>> +static const struct attribute_group *rproc_devgroups[] = {
>>> + &rproc_devgroup,
>>> + NULL
>>> +};
>>> +
>>> +struct class rproc_class = {
>>> + .name = "remoteproc",
>>> + .dev_groups = rproc_devgroups,
>>> +};
>>> +
>>> +int __init rproc_init_sysfs(void)
>>> +{
>>> + /* create remoteproc device class for sysfs */
>>> + int err = class_register(&rproc_class);
>>> +
>>> + if (err)
>>> + pr_err("remoteproc: unable to register class\n");
>>> + return err;
>>> +}
>>> +
>>> +void __exit rproc_exit_sysfs(void)
>>> +{
>>> + class_unregister(&rproc_class);
>>> +}
>>> --
>>> 2.7.4
>>>
>>> --
>>> To unsubscribe from this list: send the line "unsubscribe
>>> linux-remoteproc" in
>>> the body of a message to majordomo@xxxxxxxxxxxxxxx
>>> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
>