[Intel-gfx] [PATCH] drm: add managed resources tied to drm_device
We have lots of these. And the cleanup code tends to be of dubious
quality. The biggest wrong pattern is that developers use devm_, which
ties the release action to the underlying struct device, whereas
all the userspace visible stuff attached to a drm_device can long
outlive that one (e.g. after a hotunplug while userspace has open
files and mmap'ed buffers). Give people what they want, but with more
correctness.
Mostly copied from devres.c, with types adjusted to fit drm_device and
a few simplifications - I didn't (yet) copy over everything. Since
the types don't match code sharing looked like a hopeless endeavour.
For now it's only super simplified, no groups, you can't remove
actions (but kfree exists, we'll need that soon). Plus all specific to
drm_device ofc, including the logging. Which I didn't bother to make
compile-time optional, since none of the other drm logging is compile
time optional either.
One tricky bit here is the chicken between allocating your
drm_device structure and initiliazing it with drm_dev_init. For
perfect onion unwinding we'd need to have the action to kfree the
allocation registered before drm_dev_init registers any of its own
release handlers. But drm_dev_init doesn't know where exactly the
drm_device is emebedded into the overall structure, and by the time it
returns it'll all be too late. And forcing drivers to be able clean up
everything except the one kzalloc is silly.
Work around this by having a very special final_kfree pointer. This
also avoids troubles with the list head possibly disappearing from
underneath us when we release all resources attached to the
drm_device.
v2: Do all the kerneldoc at the end, to avoid lots of fairly pointless
shuffling while getting everything into shape.
v3: Add static to add/del_dr (Neil)
Move typo fix to the right patch (Neil)
v4: Enforce contract for drmm_add_final_kfree:
Use ksize() to check that the drm_device is indeed contained somewhere
in the final kfree(). Because we need that or the entire managed
release logic blows up in a pile of use-after-frees. Motivated by a
discussion with Laurent.
v5: Review from Laurent:
- %zu instead of casting size_t
- header guards
- sorting of includes
- guarding of data assignment if we didn't allocate it for a NULL
pointer
- delete spurious newline
- cast void* data parameter correctly in ->release call, no idea how
this even worked before
v6: Review from Sam
- Add the kerneldoc for the managed sub-struct back in, even if it
doesn't show up in the generated html somehow.
- Explain why __always_inline.
- Fix bisectability around the final kfree() in drm_dev_relase(). This
is just interim code which will disappear again.
- Some whitespace polish.
- Add debug output when drmm_add_action or drmm_kmalloc fail.
v7: My bisectability fix wasn't up to par as noticed by smatch.
v8: Remove unecessary {} around if else
v9: Use kstrdup_const, which requires kfree_const and introducing a free_dr()
helper (Thomas).
v10: kfree_const goes boom on the plain "kmalloc" assignment, somehow
we need to wrap that in kstrdup_const() too!! Also renumber revision
log, I somehow reset it midway thruh.
Cc: Thomas Zimmermann
Cc: Dan Carpenter
Cc: Sam Ravnborg
Cc: Laurent Pinchart
Cc: Neil Armstrong
Cc: "Rafael J. Wysocki"
Signed-off-by: Daniel Vetter
---
Documentation/gpu/drm-internals.rst | 6 +
drivers/gpu/drm/Makefile| 3 +-
drivers/gpu/drm/drm_drv.c | 15 ++-
drivers/gpu/drm/drm_internal.h | 3 +
drivers/gpu/drm/drm_managed.c | 193
include/drm/drm_device.h| 15 +++
include/drm/drm_managed.h | 30 +
include/drm/drm_print.h | 6 +
8 files changed, 267 insertions(+), 4 deletions(-)
create mode 100644 drivers/gpu/drm/drm_managed.c
create mode 100644 include/drm/drm_managed.h
diff --git a/Documentation/gpu/drm-internals.rst
b/Documentation/gpu/drm-internals.rst
index a73320576ca9..a6b6145fda78 100644
--- a/Documentation/gpu/drm-internals.rst
+++ b/Documentation/gpu/drm-internals.rst
@@ -132,6 +132,12 @@ be unmapped; on many devices, the ROM address decoder is
shared with
other BARs, so leaving it mapped could cause undesired behaviour like
hangs or memory corruption.
+Managed Resources
+-
+
+.. kernel-doc:: drivers/gpu/drm/drm_managed.c
+ :doc: managed resources
+
Bus-specific Device Registration and PCI Support
diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
index 7f72ef5e7811..183c60048307 100644
--- a/drivers/gpu/drm/Makefile
+++ b/drivers/gpu/drm/Makefile
@@ -17,7 +17,8 @@ drm-y :=drm_auth.o drm_cache.o \
drm_plane.o drm_color_mgmt.o drm_print.o \
drm_dumb_buffers.o drm_mode_config.o drm_vblank.o \
drm_syncobj.o drm_lease.o drm_writeback.o drm_client.o \
- drm_client_modeset.o drm_atomic_uapi.o drm_hdcp.o
+
Re: [Intel-gfx] [PATCH] drm: add managed resources tied to drm_device
Hi Daniel.
> v2: Do all the kerneldoc at the end, to avoid lots of fairly pointless
> shuffling while getting everything into shape.
>
> v3: Add static to add/del_dr (Neil)
> Move typo fix to the right patch (Neil)
>
> v4: Enforce contract for drmm_add_final_kfree:
>
> Use ksize() to check that the drm_device is indeed contained somewhere
> in the final kfree(). Because we need that or the entire managed
> release logic blows up in a pile of use-after-frees. Motivated by a
> discussion with Laurent.
>
> v5: Review from Laurent:
> - %zu instead of casting size_t
> - header guards
> - sorting of includes
> - guarding of data assignment if we didn't allocate it for a NULL
> pointer
> - delete spurious newline
> - cast void* data parameter correctly in ->release call, no idea how
> this even worked before
>
> v3: Review from Sam
> - Add the kerneldoc for the managed sub-struct back in, even if it
> doesn't show up in the generated html somehow.
> - Explain why __always_inline.
> - Fix bisectability around the final kfree() in drm_dev_relase(). This
> is just interim code which will disappear again.
> - Some whitespace polish.
> - Add debug output when drmm_add_action or drmm_kmalloc fail.
>
> v4: My bisectability fix wasn't up to par as noticed by smatch.
Counting is a difficult, let's restart from v3 :-)
>
> Cc: Dan Carpenter
> Cc: Sam Ravnborg
> Cc: Laurent Pinchart
> Cc: Neil Armstrong Cc: Greg Kroah-Hartman
> Cc: "Rafael J. Wysocki"
> Signed-off-by: Daniel Vetter
Looks good now.
Reviewed-by: Sam Ravnborg
> ---
> Documentation/gpu/drm-internals.rst | 6 +
> drivers/gpu/drm/Makefile| 3 +-
> drivers/gpu/drm/drm_drv.c | 12 +-
> drivers/gpu/drm/drm_internal.h | 3 +
> drivers/gpu/drm/drm_managed.c | 186
> include/drm/drm_device.h| 15 +++
> include/drm/drm_managed.h | 30 +
> include/drm/drm_print.h | 6 +
> 8 files changed, 259 insertions(+), 2 deletions(-)
> create mode 100644 drivers/gpu/drm/drm_managed.c
> create mode 100644 include/drm/drm_managed.h
>
> diff --git a/Documentation/gpu/drm-internals.rst
> b/Documentation/gpu/drm-internals.rst
> index a73320576ca9..a6b6145fda78 100644
> --- a/Documentation/gpu/drm-internals.rst
> +++ b/Documentation/gpu/drm-internals.rst
> @@ -132,6 +132,12 @@ be unmapped; on many devices, the ROM address decoder is
> shared with
> other BARs, so leaving it mapped could cause undesired behaviour like
> hangs or memory corruption.
>
> +Managed Resources
> +-
> +
> +.. kernel-doc:: drivers/gpu/drm/drm_managed.c
> + :doc: managed resources
> +
> Bus-specific Device Registration and PCI Support
>
>
> diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
> index 7f72ef5e7811..183c60048307 100644
> --- a/drivers/gpu/drm/Makefile
> +++ b/drivers/gpu/drm/Makefile
> @@ -17,7 +17,8 @@ drm-y := drm_auth.o drm_cache.o \
> drm_plane.o drm_color_mgmt.o drm_print.o \
> drm_dumb_buffers.o drm_mode_config.o drm_vblank.o \
> drm_syncobj.o drm_lease.o drm_writeback.o drm_client.o \
> - drm_client_modeset.o drm_atomic_uapi.o drm_hdcp.o
> + drm_client_modeset.o drm_atomic_uapi.o drm_hdcp.o \
> + drm_managed.o
>
> drm-$(CONFIG_DRM_LEGACY) += drm_legacy_misc.o drm_bufs.o drm_context.o
> drm_dma.o drm_scatter.o drm_lock.o
> drm-$(CONFIG_DRM_LIB_RANDOM) += lib/drm_random.o
> diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
> index 9fcd6ab3c154..d36e3812bedc 100644
> --- a/drivers/gpu/drm/drm_drv.c
> +++ b/drivers/gpu/drm/drm_drv.c
> @@ -629,6 +629,9 @@ int drm_dev_init(struct drm_device *dev,
> dev->dev = get_device(parent);
> dev->driver = driver;
>
> + INIT_LIST_HEAD(>managed.resources);
> + spin_lock_init(>managed.lock);
> +
> /* no per-device feature limits by default */
> dev->driver_features = ~0u;
>
> @@ -828,8 +831,15 @@ static void drm_dev_release(struct kref *ref)
> dev->driver->release(dev);
> } else {
> drm_dev_fini(dev);
> - kfree(dev);
> }
> +
> + drm_managed_release(dev);
> +
> + if (!dev->driver->release && !dev->managed.final_kfree) {
> + WARN_ON(!list_empty(>managed.resources));
> + kfree(dev);
> + } else if (dev->managed.final_kfree)
> + kfree(dev->managed.final_kfree);
> }
>
> /**
> diff --git a/drivers/gpu/drm/drm_internal.h b/drivers/gpu/drm/drm_internal.h
> index aeec2e68d772..8c2628dfc6c7 100644
> --- a/drivers/gpu/drm/drm_internal.h
> +++ b/drivers/gpu/drm/drm_internal.h
> @@ -89,6 +89,9 @@ void drm_prime_remove_buf_handle_locked(struct
> drm_prime_file_private *prime_fpr
> struct drm_minor *drm_minor_acquire(unsigned int minor_id);
> void drm_minor_release(struct drm_minor *minor);
>
> +/*
[Intel-gfx] [PATCH] drm: add managed resources tied to drm_device
We have lots of these. And the cleanup code tends to be of dubious quality. The biggest wrong pattern is that developers use devm_, which ties the release action to the underlying struct device, whereas all the userspace visible stuff attached to a drm_device can long outlive that one (e.g. after a hotunplug while userspace has open files and mmap'ed buffers). Give people what they want, but with more correctness. Mostly copied from devres.c, with types adjusted to fit drm_device and a few simplifications - I didn't (yet) copy over everything. Since the types don't match code sharing looked like a hopeless endeavour. For now it's only super simplified, no groups, you can't remove actions (but kfree exists, we'll need that soon). Plus all specific to drm_device ofc, including the logging. Which I didn't bother to make compile-time optional, since none of the other drm logging is compile time optional either. One tricky bit here is the chicken between allocating your drm_device structure and initiliazing it with drm_dev_init. For perfect onion unwinding we'd need to have the action to kfree the allocation registered before drm_dev_init registers any of its own release handlers. But drm_dev_init doesn't know where exactly the drm_device is emebedded into the overall structure, and by the time it returns it'll all be too late. And forcing drivers to be able clean up everything except the one kzalloc is silly. Work around this by having a very special final_kfree pointer. This also avoids troubles with the list head possibly disappearing from underneath us when we release all resources attached to the drm_device. v2: Do all the kerneldoc at the end, to avoid lots of fairly pointless shuffling while getting everything into shape. v3: Add static to add/del_dr (Neil) Move typo fix to the right patch (Neil) v4: Enforce contract for drmm_add_final_kfree: Use ksize() to check that the drm_device is indeed contained somewhere in the final kfree(). Because we need that or the entire managed release logic blows up in a pile of use-after-frees. Motivated by a discussion with Laurent. v5: Review from Laurent: - %zu instead of casting size_t - header guards - sorting of includes - guarding of data assignment if we didn't allocate it for a NULL pointer - delete spurious newline - cast void* data parameter correctly in ->release call, no idea how this even worked before v3: Review from Sam - Add the kerneldoc for the managed sub-struct back in, even if it doesn't show up in the generated html somehow. - Explain why __always_inline. - Fix bisectability around the final kfree() in drm_dev_relase(). This is just interim code which will disappear again. - Some whitespace polish. - Add debug output when drmm_add_action or drmm_kmalloc fail. v4: My bisectability fix wasn't up to par as noticed by smatch. Cc: Dan Carpenter Cc: Sam Ravnborg Cc: Laurent Pinchart Cc: Neil Armstrong Cc: "Rafael J. Wysocki" Signed-off-by: Daniel Vetter --- Documentation/gpu/drm-internals.rst | 6 + drivers/gpu/drm/Makefile| 3 +- drivers/gpu/drm/drm_drv.c | 12 +- drivers/gpu/drm/drm_internal.h | 3 + drivers/gpu/drm/drm_managed.c | 186 include/drm/drm_device.h| 15 +++ include/drm/drm_managed.h | 30 + include/drm/drm_print.h | 6 + 8 files changed, 259 insertions(+), 2 deletions(-) create mode 100644 drivers/gpu/drm/drm_managed.c create mode 100644 include/drm/drm_managed.h diff --git a/Documentation/gpu/drm-internals.rst b/Documentation/gpu/drm-internals.rst index a73320576ca9..a6b6145fda78 100644 --- a/Documentation/gpu/drm-internals.rst +++ b/Documentation/gpu/drm-internals.rst @@ -132,6 +132,12 @@ be unmapped; on many devices, the ROM address decoder is shared with other BARs, so leaving it mapped could cause undesired behaviour like hangs or memory corruption. +Managed Resources +- + +.. kernel-doc:: drivers/gpu/drm/drm_managed.c + :doc: managed resources + Bus-specific Device Registration and PCI Support diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile index 7f72ef5e7811..183c60048307 100644 --- a/drivers/gpu/drm/Makefile +++ b/drivers/gpu/drm/Makefile @@ -17,7 +17,8 @@ drm-y :=drm_auth.o drm_cache.o \ drm_plane.o drm_color_mgmt.o drm_print.o \ drm_dumb_buffers.o drm_mode_config.o drm_vblank.o \ drm_syncobj.o drm_lease.o drm_writeback.o drm_client.o \ - drm_client_modeset.o drm_atomic_uapi.o drm_hdcp.o + drm_client_modeset.o drm_atomic_uapi.o drm_hdcp.o \ + drm_managed.o drm-$(CONFIG_DRM_LEGACY) += drm_legacy_misc.o drm_bufs.o drm_context.o drm_dma.o drm_scatter.o drm_lock.o drm-$(CONFIG_DRM_LIB_RANDOM) += lib/drm_random.o diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c index
