Re: [RFC PATCH 4/6] char: fastrpc: Add support for create remote init process

[Srinivas Kandagatla]

Thanks Arnd for the review comments,

On 30/11/18 13:26, Arnd Bergmann wrote:
> On Fri, Nov 30, 2018 at 11:48 AM Srinivas Kandagatla
> <srinivas.kandagatla@xxxxxxxxxx> wrote:
>
> > +
> > +static int fastrpc_init_process(struct fastrpc_user *fl,
> > +                               struct fastrpc_ioctl_init *init)
> > +{
> > +       struct fastrpc_ioctl_invoke *ioctl;
> > +       struct fastrpc_phy_page pages[1];
> > +       struct fastrpc_map *file = NULL, *mem = NULL;
> > +       struct fastrpc_buf *imem = NULL;
> > +       int err = 0;
> > +
> > +       ioctl = kzalloc(sizeof(*ioctl), GFP_KERNEL);
> > +       if (!ioctl)
> > +               return -ENOMEM;
> > +
> > +       if (init->flags == FASTRPC_INIT_ATTACH) {
> > +               remote_arg_t ra[1];
> > +               int tgid = fl->tgid;
> > +
> > +               ra[0].buf.pv = (void *)&tgid;
> > +               ra[0].buf.len = sizeof(tgid);
> > +               ioctl->handle = 1;
> > +               ioctl->sc = FASTRPC_SCALARS(FASTRPC_RMID_INIT_ATTACH, 1, 0);
> > +               ioctl->pra = ra;
> > +               fl->pd = 0;
> > +
> > +               err = fastrpc_internal_invoke(fl, 1, ioctl);
> > +               if (err)
> > +                       goto bail;
>
> It doesn't seem right to me to dynamically allocate an 'ioctl' data structure
> from kernel context and pass that down to another function. Maybe eliminate
> that structure and change fastrpc_internal_invoke to take the individual
> arguments here instead of a pointer?
Yes, I totally agree with you, Will rework this part as suggested.
> > +       } else if (init->flags == FASTRPC_INIT_CREATE) {
>
> How about splitting each flags== case into a separate function?

Once I move this to a command code then make this a separate function.
> > diff --git a/include/uapi/linux/fastrpc.h b/include/uapi/linux/fastrpc.h
> > index 8fec66601337..6b596fc7ddf3 100644
> > --- a/include/uapi/linux/fastrpc.h
> > +++ b/include/uapi/linux/fastrpc.h
> > @@ -6,6 +6,12 @@
> >   #include <linux/types.h>
> >
> >   #define FASTRPC_IOCTL_INVOKE   _IOWR('R', 3, struct fastrpc_ioctl_invoke)
> > +#define FASTRPC_IOCTL_INIT     _IOWR('R', 4, struct fastrpc_ioctl_init)
> > +
> > +/* INIT a new process or attach to guestos */
> > +#define FASTRPC_INIT_ATTACH      0
> > +#define FASTRPC_INIT_CREATE      1
> > +#define FASTRPC_INIT_CREATE_STATIC  2
>
> Maybe use three command codes here, and remove the 'flags' member?
Make sense, will do it in next version.

> > @@ -53,4 +59,16 @@ struct fastrpc_ioctl_invoke {
> >          unsigned int *crc;
> >   };
> >
> > +struct fastrpc_ioctl_init {
> > +       uint32_t flags;         /* one of FASTRPC_INIT_* macros */
> > +       uintptr_t file;         /* pointer to elf file */
> > +       uint32_t filelen;       /* elf file length */
> > +       int32_t filefd;         /* ION fd for the file */
>
> What does this have to do with ION? The driver seems to otherwise
> just use the generic dma_buf interfaces.
Yes, the driver just uses dma_buf, it looks like leftover from downstream!

> > +       uintptr_t mem;          /* mem for the PD */
> > +       uint32_t memlen;        /* mem length */
> > +       int32_t memfd;          /* fd for the mem */
> > +       int attrs;
> > +       unsigned int siglen;
> > +};
>
> This structure is again not suitable for ioctls. Please used fixed-length
> members and no holes in the structure.
Sure, Will recheck all the structures before sending next version!


--srini
>         Arnd