[Mesa-dev] [PATCH] xf86drm: Fix error path in drmGetDevice2

[Mariusz Ceier]

I think chasing all the invocations of drmGetDevice2 is wrong - since
it's drmGetDevice2 that's broken, not the code that uses it. Code that
uses drmGetDevice2 expects it to return error when device has not been
found.

If setting *device in error path is not good, the patch can be
modified to not set *device to NULL and return error when it was never
assigned in the drmGetDevice2 function - it should also work, though I
have not tried it.



On 29 July 2018 at 19:20, Christoph Haag <haagch at frickel.club> wrote:
> I've reported this here:
> https://bugs.freedesktop.org/show_bug.cgi?id=107384
>
> The patch in the comments initializing drmDevicePtr device to NULL makes
> it work properly for me.
>
> I don't think the patch is on the mailing list yet. It's probably a good
> idea to check if there are more places where this initialization needs
> to be done...
>
>
> On 29.07.2018 10:20, Mariusz Ceier wrote:
>> In drmGetDevice2 when no local device is found or when
>> drm_device_has_rdev filters out all devices, *device might be left
>> uninitialized causing drmGetDevice2 to not return error - since
>> it's only returned when *device == NULL.
>>
>> Above leads to crash in the firefox in system with amdgpu.
>>
>> With this change firefox displays:
>>
>> libGL error: MESA-LOADER: failed to retrieve device information
>> libGL error: unable to load driver: amdgpu_dri.so
>> libGL error: driver pointer missing
>> libGL error: failed to load driver: amdgpu
>> libGL error: MESA-LOADER: failed to retrieve device information
>> libGL error: unable to load driver: amdgpu_dri.so
>> libGL error: driver pointer missing
>> libGL error: failed to load driver: amdgpu
>>
>> and doesn't crash.
>>
>> Signed-off-by: Mariusz Ceier <mceier+mesa-dev at gmail.com>
>> ---
>>  xf86drm.c | 2 ++
>>  1 file changed, 2 insertions(+)
>>
>> diff --git a/xf86drm.c b/xf86drm.c
>> index 1e621e99..336d64de 100644
>> --- a/xf86drm.c
>> +++ b/xf86drm.c
>> @@ -3935,6 +3935,8 @@ int drmGetDevice2(int fd, uint32_t flags, drmDevicePtr *device)
>>
>>      drmFoldDuplicatedDevices(local_devices, node_count);
>>
>> +    *device = NULL;
>> +
>>      for (i = 0; i < node_count; i++) {
>>          if (!local_devices[i])
>>              continue;
>>
>