Am 14.01.20 um 17:20 schrieb Nirmoy:
On 1/14/20 5:01 PM, Christian König wrote:
Am 14.01.20 um 16:43 schrieb Nirmoy Das:
Jobs submitted in an entity should execute in the order those jobs
are submitted. We make sure that by checking entity->job_queue in
drm_sched_entity_select_rq() so that we don't loadbalance jobs within
an entity.
But because we update entity->job_queue later in
drm_sched_entity_push_job(),
there remains a open window when it is possibe that entity->rq might
get
updated by drm_sched_entity_select_rq() which should not be allowed.
NAK, concurrent calls to
drm_sched_job_init()/drm_sched_entity_push_job() are not allowed in
the first place or otherwise we mess up the fence sequence order and
risk memory corruption.
if I am not missing something, I don't see any lock securing
drm_sched_job_init()/drm_sched_entity_push_job() calls in
amdgpu_cs_submit().
See one step up in the call chain, function amdgpu_cs_ioctl().
This is locking the page tables, which also makes access to the context
and entities mutual exclusive:
r = amdgpu_cs_parser_bos(&parser, data);
...
r = amdgpu_cs_submit(&parser, cs);
out:
And here the page tables are unlocked again:
amdgpu_cs_parser_fini(&parser, r, reserved_buffers);
Regards,
Christian.
Regards,
Nirmoy
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