gpu: nvgpu: fix race for channel sync read/write

CTS test dEQP-VK.api.object_management.max_concurrent.device_group
crashes with invalid userspace memory access.
Currently, nvgpu_submit_prepare_syncs() races with
gk20a_channel_clean_up_jobs() and this race condition is exposed when
aggressive_sync_destroy_thresh is set to non-zero value.
nvgpu_submit_prepare_syncs() gets ref for c->sync to submit job and
releases channel sync_lock immediately. Meanwhile,
gk20a_channel_worker_process() triggers gk20a_channel_clean_up_jobs(),
which destroys ref'd c->sync pointer.
Channel sync is deleted by gk20a_channel_clean_up_jobs() only if
aggressive_sync_destroy_thresh is non-zero.
So, gk20a_channel_clean_up_jobs() and nvgpu_submit_prepare_syncs() will
race only in this scenario.
Hence, if aggressive_sync_destroy_thresh value is non-zero, this patch
protects channel's sync pointer by holding channel sync_lock
during complete execution of nvgpu_submit_prepare_syncs().

Bug 2613870

Change-Id: I6f3d48aff361d1cb38c30d2ce5de276d0c55fb6f
Signed-off-by: Vedashree Vidwans <vvidwans@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/2180550
Reviewed-by: Seema Khowala <seemaj@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: Seshendra Gadagottu <sgadagottu@nvidia.com>
Reviewed-by: Vinod Gopalakrishnakurup <vinodg@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

0 files changed, 0 insertions, 0 deletions