Re: [PATCH v6 1/9] tty: n_gsm: add restart flag to DLC specific ioctl config

Greg KH
2023-08-22T13:05:16Z

On Thu, Aug 17, 2023 at 11:32:23AM +0200, D. Starke wrote:
> From: Daniel Starke <daniel.starke@siemens.com>
>
> Currently, changing the parameters of a DLCI gives no direct control to the
> user whether this should trigger a channel reset or not. The decision is
> solely made by the driver based on the assumption which parameter changes
> are compatible or not. Therefore, the user has no means to perform an
> automatic channel reset after parameter configuration for non-conflicting
> changes.
>
> Add the parameter 'flags' to 'gsm_dlci_config' to force a channel reset
> after ioctl setting regardless of whether the changes made require this or
> not by setting this to 'GSM_FL_RESTART'.
>
> Note that 'GSM_FL_RESTART' is currently the only allow flag to allow
> additions here.
>
> Signed-off-by: Daniel Starke <daniel.starke@siemens.com>
> ---
> drivers/tty/n_gsm.c | 4 ++++
> include/uapi/linux/gsmmux.h | 15 ++++++++++++++-
> 2 files changed, 18 insertions(+), 1 deletion(-)
>
> v5 -> v6:
> No changes.
>
> Link: https://lore.kernel.org/all/20230517155704.5701-1-daniel.starke@siemens.com/
>
> diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
> index 42759500b79e..a4268515920e 100644
> --- a/drivers/tty/n_gsm.c
> +++ b/drivers/tty/n_gsm.c
> @@ -2532,6 +2532,8 @@ static int gsm_dlci_config(struct gsm_dlci *dlci, struct gsm_dlci_config *dc, in
> return -EINVAL;
> if (dc->k > 7)
> return -EINVAL;
> + if (dc->flags & ~GSM_FL_RESTART) /* allow future extensions */
> + return -EINVAL;
>
> /*
> * See what is needed for reconfiguration
> @@ -2546,6 +2548,8 @@ static int gsm_dlci_config(struct gsm_dlci *dlci, struct gsm_dlci_config *dc, in
> /* Requires care */
> if (dc->priority != dlci->prio)
> need_restart = true;
> + if (dc->flags & GSM_FL_RESTART)
> + need_restart = true;
>
> if ((open && gsm->wait_config) || need_restart)
> need_open = true;
> diff --git a/include/uapi/linux/gsmmux.h b/include/uapi/linux/gsmmux.h
> index eb67884e5f38..e56e2d7ea6eb 100644
> --- a/include/uapi/linux/gsmmux.h
> +++ b/include/uapi/linux/gsmmux.h
> @@ -2,10 +2,22 @@
> #ifndef _LINUX_GSMMUX_H
> #define _LINUX_GSMMUX_H
>
> +#include <linux/const.h>
> #include <linux/if.h>
> #include <linux/ioctl.h>
> #include <linux/types.h>
>
> +/*
> + * flags definition for n_gsm
> + *
> + * Used by:
> + * struct gsm_dlci_config.flags
> + */
> +/* Forces a DLCI reset if set. Otherwise, a DLCI reset is only done if
> + * incompatible settings were provided. Always cleared on retrieval.
> + */
> +#define GSM_FL_RESTART _BITUL(0)
> +
> struct gsm_config
> {
> unsigned int adaption;
> @@ -58,7 +70,8 @@ struct gsm_dlci_config {
> __u32 priority; /* Priority (0 for default value) */
> __u32 i; /* Frame type (1 = UIH, 2 = UI) */
> __u32 k; /* Window size (0 for default value) */
> - __u32 reserved[8]; /* For future use, must be initialized to zero */
> + __u32 flags; /* DLCI specific flags. */

This should be called "dlci_flags" right? Otherwise when you add more
flags in the reserved area, what will you call them?

thanks,

greg k-h