On Wed, Feb 19, 2014 at 06:49:36PM +0200, Anssi Hannula wrote:
(added Dmitry to CC)
19.02.2014 13:42, Elias Vanderstuyft kirjoitti:
Hi,
Hi,
In the process of reviewing the Wine DInput translation layer, I noticed an inconvenience (in the ff-core implementation?) that can possibly lead to confusing problems to application developers (not only for Wine), in short: If a new (id==-1) effect was uploaded (look at ff-core.c::input_ff_upload(...)) that failed (e.g. returning EINVAL), ff-core will have assigned a positive number to the effect id. This can be confusing because the dev->ff->effects[] array will not contain an element at the index of that new effect id.
I agree that this is a bit confusing, and the kernel code should probably be modified to not clobber the ioctl-provided effect on failure (effect->id is set to an "undefined" value, i.e. next free effect slot).
Dmitry, WDYT?
Yeah, it looks like we need to change evdev.c to read:
error = input_ff_upload(dev, &effect, file); if (error) return error;
if (put_user(effect.id, &(((struct ff_effect __user *)p)->id))) return -EFAULT;
return 0;
Unfortunately applications should still expect changed effect ID for quite some time.
Thanks.