[PATCH] staging: vc04_services: Add 32-bit compatibility ioctls

[Eric Anholt]

Michael Zoran <mzoran at crowfest.net> writes:

> On Tue, 2016-11-08 at 13:11 +0100, Arnd Bergmann wrote:
>> On Monday, November 7, 2016 4:48:35 PM CET Michael Zoran wrote:
>> >  .../vc04_services/interface/vchiq_arm/vchiq_arm.c  | 269
>> > +++++++++++++++++++++
>> >  .../vc04_services/interface/vchiq_arm/vchiq_if.h   |  25 ++
>> >  .../interface/vchiq_arm/vchiq_ioctl.h              | 102 ++++++++
>> >  3 files changed, 396 insertions(+)
>> > 
>> > diff --git
>> > a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
>> > b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
>> > index 8fcd940..df343a0 100644
>> > --- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
>> > +++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
>> > @@ -573,12 +573,40 @@ vchiq_ioctl(struct file *file, unsigned int
>> > cmd, unsigned long arg)
>> >  				"vchiq: could not connect: %d",
>> > status);
>> >  		break;
>> >  
>> > +#if defined(CONFIG_64BIT)
>> > +	case VCHIQ_IOC_CREATE_SERVICE32:
>> > +#endif
>> >  	case VCHIQ_IOC_CREATE_SERVICE: {
>> >  		VCHIQ_CREATE_SERVICE_T args;
>> >  		USER_SERVICE_T *user_service = NULL;
>> >  		void *userdata;
>> >  		int srvstate;
>> >  
>> > +#if defined(CONFIG_64BIT)
>> > +		if (cmd == VCHIQ_IOC_CREATE_SERVICE32) {
>> 
>> Better use CONFIG_COMPAT here. Also, a simple #ifdef is sufficient
>> as neither of those symbols can be a loadable module.
>> 
>
> OK, I can clean that up and resubmit.
>
>> Also, just move all the compat handling into the .compat_ioctl
>> callback function and move out the common parts into helpers
>> for simplicity.
>> 
>
> That's a bit tricky.  Hopefully GregK will respond if he'll willing
> to approve a change that rewrites the whole ioctl path.

Another way of doing compat ioctls that doesn't rewrite your whole
non-compat ioctl path is in drivers/gpu/drm/drm_ioc32.c: the compat path
just rewrites the 32-bit ioctl into a 64-bit struct that it passes to
the normal ioctl handler.
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