Use drm_dev_unplug() to have device resources protected from user access
by DRM layer as soon as the driver is going to be unbound. Also, cancel
all pending work so associated resources can be quickly released.
Janusz Krzysztofik (2):
drm/i915: Use drm_dev_unplug()
drm/i915: Mark GEM wedged right after marking device unplugged
drivers/gpu/drm/i915/i915_drv.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
I'm resending these two patches together in series to make the robot
happy about the second one. Also, I've added the Suggested-by: clause
to credit actual Chris' contribution.
Thanks,
Janusz
--
2.20.1
From: Janusz Krzysztofik <[email protected]>
The driver does not currently support unbinding from a device which is
in use. Since open file descriptors may still be pointing into kernel
memory where the device structures used to be, entirely correct kernel
panics protect the driver from being unbound as we should not be
unbinding it before those dangling pointers have been made safe.
According to the documentation found inside drivers/gpu/drm/drm_drv.c,
drm_dev_unplug() should be used instead of drm_dev_unregister() in
order to make a device inaccessible to users as soon as it is unpluged.
Follow that advice to make those possibly dangling pointers safe,
protected by DRM layer from a user who is otherwise left pointing into
possibly reused kernel memory after the driver has been unbound from
the device. Once done, also cancel inflight operations immediately by
calling i915_gem_set_wedged().
Signed-off-by: Janusz Krzysztofik <[email protected]>
Reviewed-by: Chris Wilson <[email protected]>
---
drivers/gpu/drm/i915/i915_drv.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 9df65d386d11..66163378c481 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -1596,7 +1596,7 @@ static void i915_driver_unregister(struct drm_i915_private *dev_priv)
i915_pmu_unregister(dev_priv);
i915_teardown_sysfs(dev_priv);
- drm_dev_unregister(&dev_priv->drm);
+ drm_dev_unplug(&dev_priv->drm);
i915_gem_shrinker_unregister(dev_priv);
}
--
2.20.1
As soon as a device is considered unplugged, not only prevent pending
users from accessing the device structures but also cancel all their
pending requests so all consumed resources can be cleaned up as soon
as possible.
Suggested-by: Chris Wilson <[email protected]>
Signed-off-by: Janusz Krzysztofik <[email protected]>
Reviewed-by: Chris Wilson <[email protected]>
---
drivers/gpu/drm/i915/i915_drv.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 66163378c481..03a563ce7e6b 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -1598,6 +1598,13 @@ static void i915_driver_unregister(struct drm_i915_private *dev_priv)
i915_teardown_sysfs(dev_priv);
drm_dev_unplug(&dev_priv->drm);
+ /*
+ * After unregistering the device to prevent any new users, cancel
+ * all in-flight requests so that we can quickly unbind the active
+ * resources.
+ */
+ i915_gem_set_wedged(dev_priv);
+
i915_gem_shrinker_unregister(dev_priv);
}
--
2.20.1
On Fri, Apr 05, 2019 at 03:02:34PM +0200, Janusz Krzysztofik wrote:
> From: Janusz Krzysztofik <[email protected]>
>
> The driver does not currently support unbinding from a device which is
> in use. Since open file descriptors may still be pointing into kernel
> memory where the device structures used to be, entirely correct kernel
> panics protect the driver from being unbound as we should not be
> unbinding it before those dangling pointers have been made safe.
>
> According to the documentation found inside drivers/gpu/drm/drm_drv.c,
> drm_dev_unplug() should be used instead of drm_dev_unregister() in
> order to make a device inaccessible to users as soon as it is unpluged.
> Follow that advice to make those possibly dangling pointers safe,
> protected by DRM layer from a user who is otherwise left pointing into
> possibly reused kernel memory after the driver has been unbound from
> the device. Once done, also cancel inflight operations immediately by
> calling i915_gem_set_wedged().
>
> Signed-off-by: Janusz Krzysztofik <[email protected]>
> Reviewed-by: Chris Wilson <[email protected]>
Reviewed-by: Daniel Vetter <[email protected]>
> ---
> drivers/gpu/drm/i915/i915_drv.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index 9df65d386d11..66163378c481 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -1596,7 +1596,7 @@ static void i915_driver_unregister(struct drm_i915_private *dev_priv)
> i915_pmu_unregister(dev_priv);
>
> i915_teardown_sysfs(dev_priv);
> - drm_dev_unregister(&dev_priv->drm);
> + drm_dev_unplug(&dev_priv->drm);
>
> i915_gem_shrinker_unregister(dev_priv);
> }
> --
> 2.20.1
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
From: Janusz Krzysztofik <[email protected]>
The driver does not currently support unbinding from a device which is
in use. Since open file descriptors may still be pointing into kernel
memory where the device structures used to be, entirely correct kernel
panics protect the driver from being unbound as we should not be
unbinding it before those dangling pointers have been made safe.
According to the documentation found inside drivers/gpu/drm/drm_drv.c,
drm_dev_unplug() should be used instead of drm_dev_unregister() in
order to make a device inaccessible to users as soon as it is unpluged.
Follow that advice to make those possibly dangling pointers safe,
protected by DRM layer from a user who is otherwise left pointing into
possibly reused kernel memory after the driver has been unbound from
the device.
Signed-off-by: Janusz Krzysztofik <[email protected]>
Reviewed-by: Chris Wilson <[email protected]>
Reviewed-by: Daniel Vetter <[email protected]>
---
drivers/gpu/drm/i915/i915_drv.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 9df65d386d11..66163378c481 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -1596,7 +1596,7 @@ static void i915_driver_unregister(struct drm_i915_private *dev_priv)
i915_pmu_unregister(dev_priv);
i915_teardown_sysfs(dev_priv);
- drm_dev_unregister(&dev_priv->drm);
+ drm_dev_unplug(&dev_priv->drm);
i915_gem_shrinker_unregister(dev_priv);
}
--
2.20.1
Use drm_dev_unplug() to have device resources protected from user access
by DRM layer as soon as the driver is going to be unbound.
Janusz Krzysztofik (1):
drm/i915: Use drm_dev_unplug()
drivers/gpu/drm/i915/i915_drv.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
Since this patch should be now safe for use if merged with current
drm-next or drm-tip branch which no longer suffer from incorrectly
resolved merge confilct that was breaking it, finally fixed by commit
bd53280ef042 ("drm/drv: Fix incorrect resolution of merge conflict"),
I'm resending it with Daniel's Reviewed-by: added.
Former patch 2/2 has been dropped as it is already in drm-intel-next as
commit 141f3767e7b8 ("drm/i915: Mark GEM wedged right after marking
device unplugged"). BTW, the wersion I sent was screwed up, not
reflecting Chris' intention precisely enough, but Chris was vigilant and
fixed it. Sorry Chris.
Thanks,
Janusz
--
2.20.1