[igt-dev] [Intel-gfx] [PATCH igt 2/2] igt/gem_eio: Drop DRM_MASTER so we can reacquire it in the subtests

[Chris Wilson]

Quoting Tvrtko Ursulin (2018-04-06 09:35:41)
> 
> On 05/04/2018 19:47, Chris Wilson wrote:
> > As we reopen the fd for each subtest, and we need a DRM_MASTER, we need
> > to drop master on the original before we are allowed to claim DRM_MASTER
> > on the second.
> > 
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> > ---
> >   tests/gem_eio.c | 2 ++
> >   1 file changed, 2 insertions(+)
> > 
> > diff --git a/tests/gem_eio.c b/tests/gem_eio.c
> > index 9599e73d..66d8c18a 100644
> > --- a/tests/gem_eio.c
> > +++ b/tests/gem_eio.c
> > @@ -41,6 +41,7 @@
> >   #include <drm.h>
> >   
> >   #include "igt.h"
> > +#include "igt_device.h"
> >   #include "igt_sysfs.h"
> >   #include "sw_sync.h"
> >   
> > @@ -674,6 +675,7 @@ igt_main
> >   
> >       igt_fixture {
> >               fd = drm_open_driver(DRIVER_INTEL);
> > +             igt_device_drop_master(fd);
> 
> 
> Is it master by default? I can't spot a place which would set master 
> either in igt/lib/ or in drm.

First person to open /dev/dri/cardN gets DRM_MASTER.
 
> But in any case, should we have gem_reopen_driver attempt to drop master 
> before re-opening? And if it was successful, drop it again after 
> re-opening to end up in the same state?

Not sure. I can argue the alternative as well, what if we were testing
authentication and wanted to keep DRM_MASTER and spawn a !MASTER fd.
My first thought was the same, gem_reopen_fd() should try to ensure the
new fd has the same caps as the original, but API they be tricky to rule
out surprises. For me it's easier to say, gem_reopen_fd() follows the
DRM convention in that the second fd will not be DRM_MASTER unless you
play the DRM games. Then you can choose what games to play?
-Chris