Re: [PATCH] drm/core: Do not preserve framebuffer on rmfb.

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Op 22-03-16 om 11:50 schreef Daniel Vetter:
> On Tue, Mar 22, 2016 at 10:32:32AM +0100, Maarten Lankhorst wrote:
>> Op 21-03-16 om 18:37 schreef Daniel Vetter:
>>> On Mon, Mar 21, 2016 at 03:11:17PM +0100, Maarten Lankhorst wrote:
>>>> It turns out that preserving framebuffers after the rmfb call breaks
>>>> vmwgfx userspace. This was originally introduced because it was thought
>>>> nobody relied on the behavior, but unfortunately it seems there are
>>>> exceptions.
>>>>
>>>> drm_framebuffer_remove may fail with -EINTR now, so a straight revert
>>>> is impossible. There is no way to remove the framebuffer from the lists
>>>> and active planes without introducing a race because of the different
>>>> locking requirements. Instead call drm_framebuffer_remove from a
>>>> workqueue, which is unaffected by signals.
>>>>
>>>> Cc: stable@xxxxxxxxxxxxxxx #v4.4+
>>>> Fixes: 13803132818c ("drm/core: Preserve the framebuffer after removing it.")
>>>> Testcase: kms_flip.flip-vs-rmfb-interruptible
>>>> References: https://lists.freedesktop.org/archives/dri-devel/2016-March/102876.html
>>>> Cc: Thomas Hellstrom <thellstrom@xxxxxxxxxx>
>>>> Cc: David Herrmann <dh.herrmann@xxxxxxxxx>
>>>> ---
>>>>  drivers/gpu/drm/drm_crtc.c | 20 +++++++++++++++++++-
>>>>  1 file changed, 19 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
>>>> index e08f962288d9..b7d0b959f088 100644
>>>> --- a/drivers/gpu/drm/drm_crtc.c
>>>> +++ b/drivers/gpu/drm/drm_crtc.c
>>>> @@ -3434,6 +3434,18 @@ int drm_mode_addfb2(struct drm_device *dev,
>>>>   return 0;
>>>>  }
>>>>
>>>> +struct drm_mode_rmfb_work {
>>>> + struct work_struct work;
>>>> + struct drm_framebuffer *fb;
>>>> +};
>>>> +
>>>> +static void drm_mode_rmfb_work_fn(struct work_struct *w)
>>>> +{
>>>> + struct drm_mode_rmfb_work *arg = container_of(w, typeof(*arg), work);
>>>> +
>>>> + drm_framebuffer_remove(arg->fb);
>>> drm_framebuffer_remove still has the problem of not working correctly with
>>> atomic since atomic commit will complain if we try to do more than 1
>>> commit per ww_acquire_ctx. I think we still need an atomic version of
>>> this. Also probably a more nasty igt testcase which uses the same fb on
>>> more than one plane to be able to hit this case.
>> That's true, but a separate bug. :)
> Atm we only use drm_framebuffer_remove in atomic drivers to nuke the fbdev
> one at unload. With your patch userspace can't get there easily, and hence
> it must be fixed. Maybe separate prep patch (also cc: stable) upfront?
>
Something like this?

Unfortunately I need to collect acks first.

commit ed242f92c2e7571a6a5f649c2a67031debc73e44
Author: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
Date:   Thu Mar 17 13:42:08 2016 +0100

    drm/atomic: Add remove_fb function pointer.
    
    Use this in drm_framebuffer_remove, this is to remove the fb in an atomic way.
    
    Signed-off-by: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>

diff --git a/drivers/gpu/drm/arm/hdlcd_drv.c b/drivers/gpu/drm/arm/hdlcd_drv.c
index 56b829f97699..50ba6adb74e8 100644
--- a/drivers/gpu/drm/arm/hdlcd_drv.c
+++ b/drivers/gpu/drm/arm/hdlcd_drv.c
@@ -324,6 +324,7 @@ static struct drm_driver hdlcd_driver = {
 	.dumb_create = drm_gem_cma_dumb_create,
 	.dumb_map_offset = drm_gem_cma_dumb_map_offset,
 	.dumb_destroy = drm_gem_dumb_destroy,
+	.remove_fb = drm_atomic_helper_remove_fb,
 	.prime_handle_to_fd = drm_gem_prime_handle_to_fd,
 	.prime_fd_to_handle = drm_gem_prime_fd_to_handle,
 	.gem_prime_export = drm_gem_prime_export,
diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c
index 3d8d16402d07..5d357f729114 100644
--- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c
+++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c
@@ -711,6 +711,7 @@ static struct drm_driver atmel_hlcdc_dc_driver = {
 	.dumb_create = drm_gem_cma_dumb_create,
 	.dumb_map_offset = drm_gem_cma_dumb_map_offset,
 	.dumb_destroy = drm_gem_dumb_destroy,
+	.remove_fb = drm_atomic_helper_remove_fb,
 	.fops = &fops,
 	.name = "atmel-hlcdc",
 	.desc = "Atmel HLCD Controller DRM",
diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 4befe25c81c7..eb3b413560df 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -1960,6 +1960,72 @@ commit:
 	return 0;
 }
 
+int drm_atomic_helper_remove_fb(struct drm_framebuffer *fb)
+{
+	struct drm_modeset_acquire_ctx ctx;
+	struct drm_device *dev = fb->dev;
+	struct drm_atomic_state *state;
+	struct drm_plane *plane;
+	int ret = 0;
+	unsigned plane_mask;
+
+	state = drm_atomic_state_alloc(dev);
+	if (!state)
+		return -ENOMEM;
+
+	drm_modeset_acquire_init(&ctx, 0);
+
+retry:
+	plane_mask = 0;
+	ret = drm_modeset_lock_all_ctx(dev, &ctx);
+	if (ret)
+		goto unlock;
+
+	drm_for_each_plane(plane, dev) {
+		struct drm_plane_state *plane_state;
+
+		if (plane->state->fb != fb)
+			continue;
+
+		plane_state = drm_atomic_get_plane_state(state, plane);
+		if (IS_ERR(plane_state)) {
+			ret = PTR_ERR(plane_state);
+			goto unlock;
+		}
+
+		drm_atomic_set_fb_for_plane(plane_state, NULL);
+		ret = drm_atomic_set_crtc_for_plane(plane_state, NULL);
+		if (ret)
+			goto unlock;
+
+		plane_mask |= BIT(drm_plane_index(plane));
+
+		plane->old_fb = plane->fb;
+		plane->fb = NULL;
+	}
+
+	if (plane_mask)
+		ret = drm_atomic_commit(state);
+
+unlock:
+	if (plane_mask)
+		drm_atomic_clean_old_fb(dev, plane_mask, ret);
+
+	if (ret == -EDEADLK) {
+		drm_modeset_backoff(&ctx);
+		goto retry;
+	}
+
+	if (ret || !plane_mask)
+		drm_atomic_state_free(state);
+
+	drm_modeset_drop_locks(&ctx);
+	drm_modeset_acquire_fini(&ctx);
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_atomic_helper_remove_fb);
+
 /**
  * drm_atomic_helper_disable_all - disable all currently active outputs
  * @dev: DRM device
diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index aaf6ab42f2c1..51c5a00ffdff 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -577,6 +577,42 @@ void drm_framebuffer_cleanup(struct drm_framebuffer *fb)
 }
 EXPORT_SYMBOL(drm_framebuffer_cleanup);
 
+static int
+legacy_remove_fb(struct drm_framebuffer *fb)
+{
+	struct drm_device *dev = fb->dev;
+	struct drm_crtc *crtc;
+	struct drm_plane *plane;
+	struct drm_mode_set set;
+	int ret = 0;
+
+	/* atomic drivers must use drm_atomic_helper_remove_fb */
+	WARN_ON(drm_core_check_feature(dev, DRIVER_ATOMIC));
+
+	drm_modeset_lock_all(dev);
+	/* remove from any CRTC */
+	drm_for_each_crtc(crtc, dev) {
+		if (crtc->primary->fb == fb) {
+			/* should turn off the crtc */
+			memset(&set, 0, sizeof(struct drm_mode_set));
+			set.crtc = crtc;
+			set.fb = NULL;
+			ret = drm_mode_set_config_internal(&set);
+			if (ret)
+				goto out;
+		}
+	}
+
+	drm_for_each_plane(plane, dev) {
+		if (plane->fb == fb)
+			drm_plane_force_disable(plane);
+	}
+
+out:
+	drm_modeset_unlock_all(dev);
+	return ret;
+}
+
 /**
  * drm_framebuffer_remove - remove and unreference a framebuffer object
  * @fb: framebuffer to remove
@@ -592,9 +628,6 @@ EXPORT_SYMBOL(drm_framebuffer_cleanup);
 void drm_framebuffer_remove(struct drm_framebuffer *fb)
 {
 	struct drm_device *dev;
-	struct drm_crtc *crtc;
-	struct drm_plane *plane;
-	struct drm_mode_set set;
 	int ret;
 
 	if (!fb)
@@ -620,25 +653,13 @@ void drm_framebuffer_remove(struct drm_framebuffer *fb)
 	 * in this manner.
 	 */
 	if (atomic_read(&fb->refcount.refcount) > 1) {
-		drm_modeset_lock_all(dev);
-		/* remove from any CRTC */
-		drm_for_each_crtc(crtc, dev) {
-			if (crtc->primary->fb == fb) {
-				/* should turn off the crtc */
-				memset(&set, 0, sizeof(struct drm_mode_set));
-				set.crtc = crtc;
-				set.fb = NULL;
-				ret = drm_mode_set_config_internal(&set);
-				if (ret)
-					DRM_ERROR("failed to reset crtc %p when fb was deleted\n", crtc);
-			}
-		}
+		if (dev->driver->remove_fb)
+			ret = dev->driver->remove_fb(fb);
+		else
+			ret = legacy_remove_fb(fb);
 
-		drm_for_each_plane(plane, dev) {
-			if (plane->fb == fb)
-				drm_plane_force_disable(plane);
-		}
-		drm_modeset_unlock_all(dev);
+		if (ret)
+			DRM_ERROR("failed to remove fb %i/%p with %i\n", fb->base.id, fb, ret);
 	}
 
 	drm_framebuffer_unreference(fb);
diff --git a/drivers/gpu/drm/exynos/exynos_drm_drv.c b/drivers/gpu/drm/exynos/exynos_drm_drv.c
index 5344940c8a07..2705a315f1ec 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_drv.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_drv.c
@@ -423,6 +423,7 @@ static struct drm_driver exynos_drm_driver = {
 	.dumb_create		= exynos_drm_gem_dumb_create,
 	.dumb_map_offset	= exynos_drm_gem_dumb_map_offset,
 	.dumb_destroy		= drm_gem_dumb_destroy,
+	.remove_fb		= drm_atomic_helper_remove_fb,
 	.prime_handle_to_fd	= drm_gem_prime_handle_to_fd,
 	.prime_fd_to_handle	= drm_gem_prime_fd_to_handle,
 	.gem_prime_export	= drm_gem_prime_export,
diff --git a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
index e8d9337a66d8..f7562b178819 100644
--- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
+++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
@@ -24,6 +24,7 @@
 #include <drm/drmP.h>
 #include <drm/drm_crtc_helper.h>
 #include <drm/drm_gem_cma_helper.h>
+#include <drm/drm_atomic_helper.h>
 
 #include "fsl_dcu_drm_crtc.h"
 #include "fsl_dcu_drm_drv.h"
@@ -194,6 +195,7 @@ static struct drm_driver fsl_dcu_drm_driver = {
 	.dumb_create		= drm_gem_cma_dumb_create,
 	.dumb_map_offset	= drm_gem_cma_dumb_map_offset,
 	.dumb_destroy		= drm_gem_dumb_destroy,
+	.remove_fb		= drm_atomic_helper_remove_fb,
 	.fops			= &fsl_dcu_drm_fops,
 	.name			= "fsl-dcu-drm",
 	.desc			= "Freescale DCU DRM",
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 2a076b005af9..9cbf88adf280 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -42,6 +42,7 @@
 #include <linux/vgaarb.h>
 #include <linux/vga_switcheroo.h>
 #include <drm/drm_crtc_helper.h>
+#include <drm/drm_atomic_helper.h>
 
 static struct drm_driver driver;
 
@@ -1712,6 +1713,7 @@ static struct drm_driver driver = {
 	.dumb_create = i915_gem_dumb_create,
 	.dumb_map_offset = i915_gem_mmap_gtt,
 	.dumb_destroy = drm_gem_dumb_destroy,
+	.remove_fb = drm_atomic_helper_remove_fb,
 	.ioctls = i915_ioctls,
 	.fops = &i915_driver_fops,
 	.name = DRIVER_NAME,
diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
index d52910e2c26c..fab3d7f036ae 100644
--- a/drivers/gpu/drm/msm/msm_drv.c
+++ b/drivers/gpu/drm/msm/msm_drv.c
@@ -973,6 +973,7 @@ static struct drm_driver msm_driver = {
 	.dumb_create        = msm_gem_dumb_create,
 	.dumb_map_offset    = msm_gem_dumb_map_offset,
 	.dumb_destroy       = drm_gem_dumb_destroy,
+	.remove_fb          = drm_atomic_helper_remove_fb,
 	.prime_handle_to_fd = drm_gem_prime_handle_to_fd,
 	.prime_fd_to_handle = drm_gem_prime_fd_to_handle,
 	.gem_prime_export   = drm_gem_prime_export,
diff --git a/drivers/gpu/drm/omapdrm/omap_drv.c b/drivers/gpu/drm/omapdrm/omap_drv.c
index 80398a684cae..9f3bacbad118 100644
--- a/drivers/gpu/drm/omapdrm/omap_drv.c
+++ b/drivers/gpu/drm/omapdrm/omap_drv.c
@@ -817,6 +817,7 @@ static struct drm_driver omap_drm_driver = {
 	.dumb_create = omap_gem_dumb_create,
 	.dumb_map_offset = omap_gem_dumb_map_offset,
 	.dumb_destroy = drm_gem_dumb_destroy,
+	.remove_fb = drm_atomic_helper_remove_fb,
 	.ioctls = ioctls,
 	.num_ioctls = DRM_OMAP_NUM_IOCTLS,
 	.fops = &omapdriver_fops,
diff --git a/drivers/gpu/drm/rcar-du/rcar_du_drv.c b/drivers/gpu/drm/rcar-du/rcar_du_drv.c
index ed6006bf6bd8..3b7388d87815 100644
--- a/drivers/gpu/drm/rcar-du/rcar_du_drv.c
+++ b/drivers/gpu/drm/rcar-du/rcar_du_drv.c
@@ -25,6 +25,7 @@
 #include <drm/drm_crtc_helper.h>
 #include <drm/drm_fb_cma_helper.h>
 #include <drm/drm_gem_cma_helper.h>
+#include <drm/drm_atomic_helper.h>
 
 #include "rcar_du_crtc.h"
 #include "rcar_du_drv.h"
@@ -231,6 +232,7 @@ static struct drm_driver rcar_du_driver = {
 	.dumb_create		= rcar_du_dumb_create,
 	.dumb_map_offset	= drm_gem_cma_dumb_map_offset,
 	.dumb_destroy		= drm_gem_dumb_destroy,
+	.remove_fb		= drm_atomic_helper_remove_fb,
 	.fops			= &rcar_du_fops,
 	.name			= "rcar-du",
 	.desc			= "Renesas R-Car Display Unit",
diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
index 896da09e49ee..bf2162e4b131 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
@@ -19,6 +19,7 @@
 #include <drm/drmP.h>
 #include <drm/drm_crtc_helper.h>
 #include <drm/drm_fb_helper.h>
+#include <drm/drm_atomic_helper.h>
 #include <linux/dma-mapping.h>
 #include <linux/pm_runtime.h>
 #include <linux/module.h>
@@ -290,6 +291,7 @@ static struct drm_driver rockchip_drm_driver = {
 	.dumb_create		= rockchip_gem_dumb_create,
 	.dumb_map_offset	= rockchip_gem_dumb_map_offset,
 	.dumb_destroy		= drm_gem_dumb_destroy,
+	.remove_fb		= drm_atomic_helper_remove_fb,
 	.prime_handle_to_fd	= drm_gem_prime_handle_to_fd,
 	.prime_fd_to_handle	= drm_gem_prime_fd_to_handle,
 	.gem_prime_import	= drm_gem_prime_import,
diff --git a/drivers/gpu/drm/tegra/drm.c b/drivers/gpu/drm/tegra/drm.c
index 8e6b18caa706..c60f86c8f73d 100644
--- a/drivers/gpu/drm/tegra/drm.c
+++ b/drivers/gpu/drm/tegra/drm.c
@@ -944,6 +944,8 @@ static struct drm_driver tegra_drm_driver = {
 	.dumb_map_offset = tegra_bo_dumb_map_offset,
 	.dumb_destroy = drm_gem_dumb_destroy,
 
+	.remove_fb = drm_atomic_helper_remove_fb,
+
 	.ioctls = tegra_drm_ioctls,
 	.num_ioctls = ARRAY_SIZE(tegra_drm_ioctls),
 	.fops = &tegra_drm_fops,
diff --git a/drivers/gpu/drm/vc4/vc4_drv.c b/drivers/gpu/drm/vc4/vc4_drv.c
index b7d2ff0e6e1f..4dde5d924d51 100644
--- a/drivers/gpu/drm/vc4/vc4_drv.c
+++ b/drivers/gpu/drm/vc4/vc4_drv.c
@@ -15,6 +15,7 @@
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>
 #include "drm_fb_cma_helper.h"
+#include "drm/drm_atomic_helper.h"
 
 #include "uapi/drm/vc4_drm.h"
 #include "vc4_drv.h"
@@ -115,6 +116,8 @@ static struct drm_driver vc4_drm_driver = {
 	.dumb_map_offset = drm_gem_cma_dumb_map_offset,
 	.dumb_destroy = drm_gem_dumb_destroy,
 
+	.remove_fb = drm_atomic_helper_remove_fb,
+
 	.ioctls = vc4_drm_ioctls,
 	.num_ioctls = ARRAY_SIZE(vc4_drm_ioctls),
 	.fops = &vc4_drm_fops,
diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.c b/drivers/gpu/drm/virtio/virtgpu_drv.c
index 7f898cfdc746..56912941eaf8 100644
--- a/drivers/gpu/drm/virtio/virtgpu_drv.c
+++ b/drivers/gpu/drm/virtio/virtgpu_drv.c
@@ -31,6 +31,7 @@
 #include <linux/pci.h>
 #include "drmP.h"
 #include "drm/drm.h"
+#include "drm/drm_atomic_helper.h"
 
 #include "virtgpu_drv.h"
 static struct drm_driver driver;
@@ -129,6 +130,8 @@ static struct drm_driver driver = {
 	.dumb_map_offset = virtio_gpu_mode_dumb_mmap,
 	.dumb_destroy = virtio_gpu_mode_dumb_destroy,
 
+	.remove_fb = drm_atomic_helper_remove_fb,
+
 #if defined(CONFIG_DEBUG_FS)
 	.debugfs_init = virtio_gpu_debugfs_init,
 	.debugfs_cleanup = virtio_gpu_debugfs_takedown,
diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index 3c8422c69572..31483c2fef51 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -638,6 +638,9 @@ struct drm_driver {
 			    struct drm_device *dev,
 			    uint32_t handle);
 
+	/* rmfb and drm_framebuffer_remove hook */
+	int (*remove_fb)(struct drm_framebuffer *fb);
+
 	/* Driver private ops for this object */
 	const struct vm_operations_struct *gem_vm_ops;
 
diff --git a/include/drm/drm_atomic_helper.h b/include/drm/drm_atomic_helper.h
index 9054598c9a7a..2d5ff5c80c76 100644
--- a/include/drm/drm_atomic_helper.h
+++ b/include/drm/drm_atomic_helper.h
@@ -87,6 +87,8 @@ int drm_atomic_helper_set_config(struct drm_mode_set *set);
 int __drm_atomic_helper_set_config(struct drm_mode_set *set,
 		struct drm_atomic_state *state);
 
+int drm_atomic_helper_remove_fb(struct drm_framebuffer *fb);
+
 int drm_atomic_helper_disable_all(struct drm_device *dev,
 				  struct drm_modeset_acquire_ctx *ctx);
 struct drm_atomic_state *drm_atomic_helper_suspend(struct drm_device *dev);

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