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 <hbh...@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;
}
}