Hello Mathieu,
On 6/15/21 7:53 PM, Mathieu Poirier wrote:
> On Fri, Jun 04, 2021 at 11:14:03AM +0200, Arnaud Pouliquen wrote:
>> Implement the RPMSG_CREATE_DEV_IOCTL to allow the user application to
>> initiate a communication through a new rpmsg channel.
>> This Ioctl can be used to instantiate a local rpmsg device.
>> Depending on the back-end implementation, the associated rpmsg driver is
>> probed and a NS announcement can be sent to the remote processor.
>>
>> Suggested-by: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
>> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@xxxxxxxxxxx>
>> ---
>> drivers/rpmsg/rpmsg_ctrl.c | 30 ++++++++++++++++++++++++++----
>> include/uapi/linux/rpmsg.h | 5 +++++
>> 2 files changed, 31 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/rpmsg/rpmsg_ctrl.c b/drivers/rpmsg/rpmsg_ctrl.c
>> index eeb1708548c1..4aa962df3661 100644
>> --- a/drivers/rpmsg/rpmsg_ctrl.c
>> +++ b/drivers/rpmsg/rpmsg_ctrl.c
>> @@ -23,6 +23,7 @@
>> #include <uapi/linux/rpmsg.h>
>>
>> #include "rpmsg_char.h"
>> +#include "rpmsg_internal.h"
>>
>> static dev_t rpmsg_major;
>>
>> @@ -37,11 +38,13 @@ static DEFINE_IDA(rpmsg_minor_ida);
>> * @rpdev: underlaying rpmsg device
>> * @cdev: cdev for the ctrl device
>> * @dev: device for the ctrl device
>> + * @ctrl_lock: serialize the ioctrls.
>> */
>> struct rpmsg_ctrldev {
>> struct rpmsg_device *rpdev;
>> struct cdev cdev;
>> struct device dev;
>> + struct mutex ctrl_lock;
>> };
>>
>> static int rpmsg_ctrldev_open(struct inode *inode, struct file *filp)
>> @@ -70,9 +73,8 @@ static long rpmsg_ctrldev_ioctl(struct file *fp, unsigned int cmd,
>> void __user *argp = (void __user *)arg;
>> struct rpmsg_endpoint_info eptinfo;
>> struct rpmsg_channel_info chinfo;
>> -
>> - if (cmd != RPMSG_CREATE_EPT_IOCTL)
>> - return -EINVAL;
>> + struct rpmsg_device *rpdev;
>> + int ret = 0;
>>
>> if (copy_from_user(&eptinfo, argp, sizeof(eptinfo)))
>> return -EFAULT;
>> @@ -82,7 +84,26 @@ static long rpmsg_ctrldev_ioctl(struct file *fp, unsigned int cmd,
>> chinfo.src = eptinfo.src;
>> chinfo.dst = eptinfo.dst;
>>
>> - return rpmsg_chrdev_eptdev_create(ctrldev->rpdev, &ctrldev->dev, chinfo);
>> + mutex_lock(&ctrldev->ctrl_lock);
>
> Do we need a lock here? I thought the character device layer would guarantee
> accesses on a file handler would be atomic... Am I wrong?
>
It is a good point! from my understanding, using "unlocked_ioctl" ops, the
driver has to handle is own atomic protection.
I will try to hack the code to verify this.
Thanks,
Arnaud
>> + switch (cmd) {
>> + case RPMSG_CREATE_EPT_IOCTL:
>> + ret = rpmsg_chrdev_eptdev_create(ctrldev->rpdev, &ctrldev->dev, chinfo);
>> + break;
>> +
>> + case RPMSG_CREATE_DEV_IOCTL:
>> + rpdev = rpmsg_create_channel(ctrldev->rpdev, &chinfo);
>> + if (!rpdev) {
>> + dev_err(&ctrldev->dev, "failed to create %s channel\n", chinfo.name);
>> + ret = -ENXIO;
>> + }
>> + break;
>> +
>> + default:
>> + ret = -EINVAL;
>> + }
>> + mutex_unlock(&ctrldev->ctrl_lock);
>> +
>> + return ret;
>> };
>>
>> static const struct file_operations rpmsg_ctrldev_fops = {
>> @@ -119,6 +140,7 @@ static int rpmsg_ctrldev_probe(struct rpmsg_device *rpdev)
>> device_initialize(dev);
>> dev->parent = &rpdev->dev;
>>
>> + mutex_init(&ctrldev->ctrl_lock);
>> cdev_init(&ctrldev->cdev, &rpmsg_ctrldev_fops);
>> ctrldev->cdev.owner = THIS_MODULE;
>>
>> diff --git a/include/uapi/linux/rpmsg.h b/include/uapi/linux/rpmsg.h
>> index f5ca8740f3fb..f9d5a74e7801 100644
>> --- a/include/uapi/linux/rpmsg.h
>> +++ b/include/uapi/linux/rpmsg.h
>> @@ -33,4 +33,9 @@ struct rpmsg_endpoint_info {
>> */
>> #define RPMSG_DESTROY_EPT_IOCTL _IO(0xb5, 0x2)
>>
>> +/**
>> + * Instantiate a rpmsg service device.
>> + */
>> +#define RPMSG_CREATE_DEV_IOCTL _IOW(0xb5, 0x3, struct rpmsg_endpoint_info)
>> +
>> #endif
>> --
>> 2.17.1
>>
