Is my understanding wrong ?...
The first thing that cancel_delayed_work_sync() does is it takes the
work item from the TODO list.
The it makes sure that the work is currently not running on another CPU.
The return value just indicates if the work was still on the TODO list
or not, e.g. when false is returned when the work was already done
before the call was made, true otherwise.
So the while loop isn't necessary here.
Regards,
Christian.
Am 27.02.2018 um 10:09 schrieb Liu, Monk:
Never use schedule() in a while loop as long as you don't work on core locking
primitives or interrupt handling or stuff like that. In this particular case a
single call to cancel_delayed_work_sync() should be sufficient.
I thought that only one call on cancel_delayed_work_sync() cannot guarantee
that after this function returned, the work had been finished, so if the work
is still pending (return you TRUE) there
And the caller just continue and release driver, we would run to page fault in
that work since all structures pointers accessed in that work is invalid now
That's why I use a while() loop to keep calling cancel_delayed_work_sync() till
the work is not pending any more
Is my understanding wrong ?...
/Monk
-----Original Message-----
From: Koenig, Christian
Sent: 2018年2月27日 16:42
To: Liu, Monk <[email protected]>; [email protected]
Subject: Re: [PATCH 09/22] drm/amdgpu: fix kmd reload bug on bare-metal
Am 27.02.2018 um 05:45 schrieb Liu, Monk:
In this case I think it would be much better to wait for the idle work before
trying to unload the driver.
I already did it:
+ if (!amdgpu_sriov_vf(adev))
+ while (cancel_delayed_work_sync(&adev->late_init_work))
+ schedule(); /* to make sure late_init_work really
stopped */
What do you mean never call "schedule()" this way ?
Never use schedule() in a while loop as long as you don't work on core locking
primitives or interrupt handling or stuff like that. In this particular case a
single call to cancel_delayed_work_sync() should be sufficient.
Additional to that I think you can drop the "if (!amdgpu_sriov_vf(adev))" check and just
test for "if (r)" or something like that. In other words if there is an error we need to
cancel the late init work independent if we are on SRIOV or bare metal.
Regards,
Christian.
Please show me how to do it to achieve the same goal and I can modify
my patch
/Monk
-----Original Message-----
From: Christian König [mailto:[email protected]]
Sent: 2018年2月26日 18:08
To: Liu, Monk <[email protected]>; [email protected]
Subject: Re: [PATCH 09/22] drm/amdgpu: fix kmd reload bug on
bare-metal
Am 26.02.2018 um 06:18 schrieb Monk Liu:
issue:
on bare-metal when doing kmd reload test, there are chance that
kernel hit fatal error afer driver unloaded/reloaded
fix:
the cause is that those "idle work" not really stopped and if kmd was
is unloaded too quick that were chance that "idle work" run after
driver structures already released which introduces this issue.
In this case I think it would be much better to wait for the idle work before
trying to unload the driver.
Change-Id: Idb0f7db771e7ca60dba925d1d0f48b1de08dc89e
Signed-off-by: Monk Liu <[email protected]>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 9 +++++++--
drivers/gpu/drm/amd/amdgpu/amdgpu_uvd.c | 3 ++-
drivers/gpu/drm/amd/amdgpu/amdgpu_vce.c | 4 +++-
3 files changed, 12 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index 54145ec..69fb5e50 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -1419,7 +1419,8 @@ static int amdgpu_device_ip_late_init(struct
amdgpu_device *adev)
}
}
- mod_delayed_work(system_wq, &adev->late_init_work,
+ if (!amdgpu_sriov_vf(adev))
+ mod_delayed_work(system_wq, &adev->late_init_work,
msecs_to_jiffies(AMDGPU_RESUME_MS));
amdgpu_device_fill_reset_magic(adev);
@@ -2087,7 +2088,11 @@ void amdgpu_device_fini(struct amdgpu_device *adev)
adev->firmware.gpu_info_fw = NULL;
}
adev->accel_working = false;
- cancel_delayed_work_sync(&adev->late_init_work);
+
+ if (!amdgpu_sriov_vf(adev))
+ while (cancel_delayed_work_sync(&adev->late_init_work))
+ schedule(); /* to make sure late_init_work really
stopped */
Never use schedule() like that.
Regards,
Christian.
+
/* free i2c buses */
if (!amdgpu_device_has_dc_support(adev))
amdgpu_i2c_fini(adev);
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_uvd.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_uvd.c
index caba610..337db57 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_uvd.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_uvd.c
@@ -299,7 +299,8 @@ int amdgpu_uvd_suspend(struct amdgpu_device *adev)
return 0;
if (!amdgpu_sriov_vf(adev))
- cancel_delayed_work_sync(&adev->uvd.idle_work);
+ while (cancel_delayed_work_sync(&adev->uvd.idle_work))
+ schedule(); /* to make sure idle work really stopped */
for (i = 0; i < adev->uvd.max_handles; ++i)
if (atomic_read(&adev->uvd.handles[i]))
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vce.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_vce.c
index a829350..2874fda 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vce.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vce.c
@@ -243,7 +243,9 @@ int amdgpu_vce_suspend(struct amdgpu_device *adev)
return 0;
if (!amdgpu_sriov_vf(adev))
- cancel_delayed_work_sync(&adev->vce.idle_work);
+ while (cancel_delayed_work_sync(&adev->vce.idle_work))
+ schedule(); /* to make sure the idle_work really
stopped */
+
/* TODO: suspending running encoding sessions isn't supported */
return -EINVAL;
}
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