[Nouveau] [PATCH 1/2] nouveau/bl: Assign different names to interfaces

[Ilia Mirkin]

On Fri, Apr 15, 2016 at 11:22 AM, Pierre Moreau <pierre.morrow at free.fr> wrote:
> On 11:06 AM - Apr 15 2016, Ilia Mirkin wrote:
>> On Fri, Apr 15, 2016 at 10:57 AM, Pierre Moreau <pierre.morrow at free.fr> wrote:
>> > Currently, every backlight interface created by Nouveau uses the same name,
>> > nv_backlight. This leads to a sysfs warning as it tries to create an already
>> > existing folder. This patch adds a incremented number to the name, but keeps
>> > the initial name as nv_backlight, to avoid possibly breaking userspace; the
>> > second interface will be named nv_backlight1, and so on.
>> >
>> > Fixes: fdo#86539
>> > Signed-off-by: Pierre Moreau <pierre.morrow at free.fr>
>> > ---
>> >  drm/nouveau/nouveau_backlight.c | 35 +++++++++++++++++++++++++++++++++--
>> >  1 file changed, 33 insertions(+), 2 deletions(-)
>> >
>> > diff --git a/drm/nouveau/nouveau_backlight.c b/drm/nouveau/nouveau_backlight.c
>> > index 89eb460..914e2cb 100644
>> > --- a/drm/nouveau/nouveau_backlight.c
>> > +++ b/drm/nouveau/nouveau_backlight.c
>> > @@ -36,6 +36,10 @@
>> >  #include "nouveau_reg.h"
>> >  #include "nouveau_encoder.h"
>> >
>> > +static atomic_t bl_interfaces_nb = { 0 };
>>
>> static data is initialized to 0, this should be unnecessary.
>
> I didn’t know that. But on the other hand, I like having it explicit, and it
> should not add any overhead.

It increases the size of the object file. I believe it's kernel policy
to avoid static initializations to 0. (Note that this doesn't hold in
regular user applications, just the kernel.)

  -ilia