On Mon 08 Nov 08:19 CST 2021, Arnaud Pouliquen wrote:
> Current implementation create/destroy a new endpoint on each
> rpmsg_eptdev_open/rpmsg_eptdev_release calls.
>
> For a rpmsg device created by the NS announcement mechanism we need to
> use a unique static endpoint that is the default rpmsg device endpoint
> associated to the channel.
>
> This patch prepares the introduction of a rpmsg channel device for the
> char device. The rpmsg channel device will require a default endpoint to
> communicate to the remote processor.
>
> Add the default_ept field in rpmsg_eptdev structure.This pointer
> determines the behavior on rpmsg_eptdev_open and rpmsg_eptdev_release call.
>
> - If default_ept == NULL:
> Use the legacy behavior by creating a new endpoint each time
> rpmsg_eptdev_open is called and release it when rpmsg_eptdev_release
> is called on /dev/rpmsgX device open/close.
>
> - If default_ept is set:
> use the rpmsg device default endpoint for the communication.
>
> Address the update of _rpmsg_chrdev_eptdev_create in a separate patch for readability.
>
> Add protection in rpmsg_eptdev_ioctl to prevent to destroy a default endpoint.
>
> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@xxxxxxxxxxx>
> ---
> drivers/rpmsg/rpmsg_char.c | 21 +++++++++++++++++++--
> 1 file changed, 19 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
> index 3daf62df69a0..6a01e8e1c111 100644
> --- a/drivers/rpmsg/rpmsg_char.c
> +++ b/drivers/rpmsg/rpmsg_char.c
> @@ -47,6 +47,8 @@ static DEFINE_IDA(rpmsg_minor_ida);
> * @queue_lock: synchronization of @queue operations
> * @queue: incoming message queue
> * @readq: wait object for incoming queue
> + * @default_ept: set to channel default endpoint if the default endpoint should be re-used
> + * on device open to prevent endpoint address update.
> */
> struct rpmsg_eptdev {
> struct device dev;
> @@ -57,10 +59,12 @@ struct rpmsg_eptdev {
>
> struct mutex ept_lock;
> struct rpmsg_endpoint *ept;
> + struct rpmsg_endpoint *default_ept;
>
> spinlock_t queue_lock;
> struct sk_buff_head queue;
> wait_queue_head_t readq;
> +
> };
>
> int rpmsg_chrdev_eptdev_destroy(struct device *dev, void *data)
> @@ -118,7 +122,15 @@ static int rpmsg_eptdev_open(struct inode *inode, struct file *filp)
>
> get_device(dev);
>
> - ept = rpmsg_create_ept(rpdev, rpmsg_ept_cb, eptdev, eptdev->chinfo);
> + /*
> + * If the default_ept is set to true, the rpmsg device default endpoint is used.
default_ept will no longer be "set to true".
Regards,
Bjorn
> + * Else a new endpoint is created on open that will be destroyed on release.
> + */
> + if (eptdev->default_ept)
> + ept = eptdev->default_ept;
> + else
> + ept = rpmsg_create_ept(rpdev, rpmsg_ept_cb, eptdev, eptdev->chinfo);
> +
> if (!ept) {
> dev_err(dev, "failed to open %s\n", eptdev->chinfo.name);
> put_device(dev);
> @@ -139,7 +151,8 @@ static int rpmsg_eptdev_release(struct inode *inode, struct file *filp)
> /* Close the endpoint, if it's not already destroyed by the parent */
> mutex_lock(&eptdev->ept_lock);
> if (eptdev->ept) {
> - rpmsg_destroy_ept(eptdev->ept);
> + if (!eptdev->default_ept)
> + rpmsg_destroy_ept(eptdev->ept);
> eptdev->ept = NULL;
> }
> mutex_unlock(&eptdev->ept_lock);
> @@ -266,6 +279,10 @@ static long rpmsg_eptdev_ioctl(struct file *fp, unsigned int cmd,
> if (cmd != RPMSG_DESTROY_EPT_IOCTL)
> return -EINVAL;
>
> + /* Don't allow to destroy a default endpoint. */
> + if (eptdev->default_ept)
> + return -EINVAL;
> +
> return rpmsg_chrdev_eptdev_destroy(&eptdev->dev, NULL);
> }
>
> --
> 2.17.1
>
