[Mesa-dev] [RFC 1/5] st/dri: Allow kms_swrast to work without a device FD

[Robert Foss]

Hey Eric!

On 05/07/18 12:35, Eric Engestrom wrote:
> On Thursday, 2018-07-05 12:07:36 +0200, Robert Foss wrote:
>> From: Tomeu Vizoso <tomeu.vizoso at collabora.com>
>>
>> A KMS device isn't strictly needed for the kms_swrast to work, so stop
>> failing to init if the FD is -1. Also don't call DRM_IOCTL_GET_CAP in
>> that case.
>>
>> This allows the driver to be used in machines where no KMS device at all
>> is present.
>>
>> Signed-off-by: Tomeu Vizoso <tomeu.vizoso at collabora.com>
>> ---
>>   src/gallium/state_trackers/dri/dri2.c | 6 ++++--
>>   1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/src/gallium/state_trackers/dri/dri2.c b/src/gallium/state_trackers/dri/dri2.c
>> index 58a6757f037..c262c0ca118 100644
>> --- a/src/gallium/state_trackers/dri/dri2.c
>> +++ b/src/gallium/state_trackers/dri/dri2.c
>> @@ -2189,7 +2189,8 @@ dri_kms_init_screen(__DRIscreen * sPriv)
>>   
>>      sPriv->driverPrivate = (void *)screen;
>>   
>> -   if (screen->fd < 0 || (fd = fcntl(screen->fd, F_DUPFD_CLOEXEC, 3)) < 0)
>> +   /* We don't really need a device FD if we are soft-rendering */
>> +   if (screen->fd >= 0 && (fd = fcntl(screen->fd, F_DUPFD_CLOEXEC, 3)) < 0)
>>         goto free_screen;
>>   
>>      if (pipe_loader_sw_probe_kms(&screen->dev, fd)) {
> 
> Aren't you going to use an uninitialised `fd` here if `screen->fd < 0`?

 From my understanding during dri2_initialize_android(), droid_open_device[1] 
will always allocate an FD or fail, before a screen is created in 
dri2_create_screen[2].

But maybe there is some part I don't quite understand.

[1] 
https://gitlab.collabora.com/robertfoss/mesa/blob/9e5f456fee2cd3f8b8dd70cc313d0ad56166ecb0/src/egl/drivers/dri2/platform_android.c#L1385

[2] 
https://gitlab.collabora.com/robertfoss/mesa/blob/9e5f456fee2cd3f8b8dd70cc313d0ad56166ecb0/src/egl/drivers/dri2/platform_android.c#L1396

> 
>> @@ -2204,7 +2205,8 @@ dri_kms_init_screen(__DRIscreen * sPriv)
>>         dri2ImageExtension.createImageWithModifiers =
>>            dri2_create_image_with_modifiers;
>>   
>> -   if (drmGetCap(sPriv->fd, DRM_CAP_PRIME, &cap) == 0 &&
>> +   if (sPriv->fd >= 0 &&
>> +          drmGetCap(sPriv->fd, DRM_CAP_PRIME, &cap) == 0 &&
>>             (cap & DRM_PRIME_CAP_IMPORT)) {
>>         dri2ImageExtension.createImageFromFds = dri2_from_fds;
>>         dri2ImageExtension.createImageFromDmaBufs = dri2_from_dma_bufs;
>> -- 
>> 2.17.1
>>
>> _______________________________________________
>> mesa-dev mailing list
>> mesa-dev at lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/mesa-dev