On 2022/4/25 23:42, Andrey Grodzovsky wrote:
On 2022-04-25 04:36, Hangyu Hua wrote:
When drm_sched_job_add_dependency() fails, dma_fence_put() will be called internally. Calling it again after drm_sched_job_add_dependency() finishes may result in a dangling pointer.
Fix this by removing redundant dma_fence_put().
Signed-off-by: Hangyu Hua hbh25y@gmail.com
drivers/gpu/drm/lima/lima_gem.c | 1 - drivers/gpu/drm/scheduler/sched_main.c | 1 - 2 files changed, 2 deletions(-)
diff --git a/drivers/gpu/drm/lima/lima_gem.c b/drivers/gpu/drm/lima/lima_gem.c index 55bb1ec3c4f7..99c8e7f6bb1c 100644 --- a/drivers/gpu/drm/lima/lima_gem.c +++ b/drivers/gpu/drm/lima/lima_gem.c @@ -291,7 +291,6 @@ static int lima_gem_add_deps(struct drm_file *file, struct lima_submit *submit) err = drm_sched_job_add_dependency(&submit->task->base, fence); if (err) { - dma_fence_put(fence); return err;
Makes sense here
} } diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c index b81fceb0b8a2..ebab9eca37a8 100644 --- a/drivers/gpu/drm/scheduler/sched_main.c +++ b/drivers/gpu/drm/scheduler/sched_main.c @@ -708,7 +708,6 @@ int drm_sched_job_add_implicit_dependencies(struct drm_sched_job *job, dma_fence_get(fence); ret = drm_sched_job_add_dependency(job, fence); if (ret) { - dma_fence_put(fence);
Not sure about this one since if you look at the relevant commits - 'drm/scheduler: fix drm_sched_job_add_implicit_dependencies' and 'drm/scheduler: fix drm_sched_job_add_implicit_dependencies harder' You will see that the dma_fence_put here balances the extra dma_fence_get above
Andrey
I don't think so. I checked the call chain and found no additional dma_fence_get(). But dma_fence_get() needs to be called before drm_sched_job_add_dependency() to keep the counter balanced. On the other hand, dma_fence_get() and dma_fence_put() are meaningless here if threre is an extra dma_fence_get() beacause counter will not decrease to 0 during drm_sched_job_add_dependency().
I check the call chain as follows:
msm_ioctl_gem_submit() -> submit_fence_sync() -> drm_sched_job_add_implicit_dependencies()
Thanks, Hangyu
return ret; } }