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

Greg KH
2023-08-22T13:05:50Z

On Tue, Aug 22, 2023 at 03:05:10PM +0200, Greg KH wrote:
> 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?

Oh nevermind, the name of the structure has it there, this is fine, I'll
take this...

thanks,

greg k-h