linux/include/drm/drm_device.h

406 lines
10 KiB

drm/gem: Add huge tmpfs mountpoint helpers Add the drm_gem_huge_mnt_create() and drm_gem_get_huge_mnt() helpers to avoid code duplication in the i915, V3D, Panfrost and Panthor drivers. The former creates and mounts a dedicated huge tmpfs mountpoint, for the lifetime of a DRM device, used at GEM object initialization. The latter retrieves the dedicated huge tmpfs mountpoint used by a DRM device. The next commits will port drivers to these helpers. v3: - store huge tmpfs mountpoint in drm_device v4: - return 0 in builds with CONFIG_TRANSPARENT_HUGEPAGE=n - return 0 when huge_mnt already exists - use new vfs_parse_fs_string() helper v5: - remove warning on !dev->huge_mnt and reset to NULL on free - inline drm_gem_huge_mnt_create() to remove func from text and avoid calls in builds with CONFIG_TRANSPARENT_HUGEPAGE=n - compile out drm_device's huge_mnt field in builds with CONFIG_TRANSPARENT_HUGEPAGE=n - add drm_gem_has_huge_mnt() helper v6: - move huge_mnt doc into ifdef'd section - either inline or export drm_gem_huge_mnt_create() v7: - include <drm/drm_device.h> in drm_gem.h v9: - replace drm_gem_has_huge_mnt() by drm_gem_get_huge_mnt() v11: - doc fixes - add Boris and Maíra R-bs Signed-off-by: Loïc Molinari <loic.molinari@collabora.com> Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com> Reviewed-by: Maíra Canal <mcanal@igalia.com> Link: https://patch.msgid.link/20251205182231.194072-5-loic.molinari@collabora.com Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
2025-12-05 19:22:25 +01:00
drm: Introduce device wedged event Introduce device wedged event, which notifies userspace of 'wedged' (hanged/unusable) state of the DRM device through a uevent. This is useful especially in cases where the device is no longer operating as expected and has become unrecoverable from driver context. Purpose of this implementation is to provide drivers a generic way to recover the device with the help of userspace intervention without taking any drastic measures (like resetting or re-enumerating the full bus, on which the underlying physical device is sitting) in the driver. A 'wedged' device is basically a device that is declared dead by the driver after exhausting all possible attempts to recover it from driver context. The uevent is the notification that is sent to userspace along with a hint about what could possibly be attempted to recover the device from userspace and bring it back to usable state. Different drivers may have different ideas of a 'wedged' device depending on hardware implementation of the underlying physical device, and hence the vendor agnostic nature of the event. It is up to the drivers to decide when they see the need for device recovery and how they want to recover from the available methods. Driver prerequisites -------------------- The driver, before opting for recovery, needs to make sure that the 'wedged' device doesn't harm the system as a whole by taking care of the prerequisites. Necessary actions must include disabling DMA to system memory as well as any communication channels with other devices. Further, the driver must ensure that all dma_fences are signalled and any device state that the core kernel might depend on is cleaned up. All existing mmaps should be invalidated and page faults should be redirected to a dummy page. Once the event is sent, the device must be kept in 'wedged' state until the recovery is performed. New accesses to the device (IOCTLs) should be rejected, preferably with an error code that resembles the type of failure the device has encountered. This will signify the reason for wedging, which can be reported to the application if needed. Recovery -------- Current implementation defines three recovery methods, out of which, drivers can use any one, multiple or none. Method(s) of choice will be sent in the uevent environment as ``WEDGED=<method1>[,..,<methodN>]`` in order of less to more side-effects. If driver is unsure about recovery or method is unknown (like soft/hard system reboot, firmware flashing, physical device replacement or any other procedure which can't be attempted on the fly), ``WEDGED=unknown`` will be sent instead. Userspace consumers can parse this event and attempt recovery as per the following expectations. =============== ======================================== Recovery method Consumer expectations =============== ======================================== none optional telemetry collection rebind unbind + bind driver bus-reset unbind + bus reset/re-enumeration + bind unknown consumer policy =============== ======================================== The only exception to this is ``WEDGED=none``, which signifies that the device was temporarily 'wedged' at some point but was recovered from driver context using device specific methods like reset. No explicit recovery is expected from the consumer in this case, but it can still take additional steps like gathering telemetry information (devcoredump, syslog). This is useful because the first hang is usually the most critical one which can result in consequential hangs or complete wedging. Consumer prerequisites ---------------------- It is the responsibility of the consumer to make sure that the device or its resources are not in use by any process before attempting recovery. With IOCTLs erroring out, all device memory should be unmapped and file descriptors should be closed to prevent leaks or undefined behaviour. The idea here is to clear the device of all user context beforehand and set the stage for a clean recovery. Example ------- Udev rule:: SUBSYSTEM=="drm", ENV{WEDGED}=="rebind", DEVPATH=="*/drm/card[0-9]", RUN+="/path/to/rebind.sh $env{DEVPATH}" Recovery script:: #!/bin/sh DEVPATH=$(readlink -f /sys/$1/device) DEVICE=$(basename $DEVPATH) DRIVER=$(readlink -f $DEVPATH/driver) echo -n $DEVICE > $DRIVER/unbind echo -n $DEVICE > $DRIVER/bind Customization ------------- Although basic recovery is possible with a simple script, consumers can define custom policies around recovery. For example, if the driver supports multiple recovery methods, consumers can opt for the suitable one depending on scenarios like repeat offences or vendor specific failures. Consumers can also choose to have the device available for debugging or telemetry collection and base their recovery decision on the findings. This is useful especially when the driver is unsure about recovery or method is unknown. v4: s/drm_dev_wedged/drm_dev_wedged_event Use drm_info() (Jani) Kernel doc adjustment (Aravind) v5: Send recovery method with uevent (Lina) v6: Access wedge_recovery_opts[] using helper function (Jani) Use snprintf() (Jani) v7: Convert recovery helpers into regular functions (Andy, Jani) Aesthetic adjustments (Andy) Handle invalid recovery method v8: Allow sending multiple methods with uevent (Lucas, Michal) static_assert() globally (Andy) v9: Provide 'none' method for device reset (Christian) Provide recovery opts using switch cases v11: Log device reset (André) Signed-off-by: Raag Jadav <raag.jadav@intel.com> Reviewed-by: André Almeida <andrealmeid@igalia.com> Reviewed-by: Christian König <christian.koenig@amd.com> Link: https://patchwork.freedesktop.org/patch/msgid/20250204070528.1919158-2-raag.jadav@intel.com Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
2025-02-04 12:35:24 +05:30
drm: Add a vendor-specific recovery method to drm device wedged uevent Address the need for a recovery method (firmware flash on Firmware errors) introduced in the later patches of Xe KMD. Whenever XE KMD detects a firmware error, a firmware flash is required to recover the device to normal operation. The initial proposal to use 'firmware-flash' as a recovery method was not applicable to other drivers and could cause multiple recovery methods specific to vendors to be added. To address this a more generic 'vendor-specific' method is introduced, guiding users to refer to vendor specific documentation and system logs for detailed vendor specific recovery procedure. Add a recovery method 'WEDGED=vendor-specific' for such errors. Vendors must provide additional recovery documentation if this method is used. It is the responsibility of the consumer to refer to the correct vendor specific documentation and usecase before attempting a recovery. For example: If driver is XE KMD, the consumer must refer to the documentation of 'Device Wedging' under 'Documentation/gpu/xe/'. v2: fix documentation (Raag) v3: add more details to commit message (Sima, Rodrigo, Raag) add an example script to the documentation (Raag) v4: use consistent naming (Raag) v5: fix commit message v6: add more documentation Cc: André Almeida <andrealmeid@igalia.com> Cc: Christian König <christian.koenig@amd.com> Cc: David Airlie <airlied@gmail.com> Cc: Simona Vetter <simona.vetter@ffwll.ch> Cc: Maxime Ripard <mripard@kernel.org> Signed-off-by: Riana Tauro <riana.tauro@intel.com> Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com> Acked-by: Maxime Ripard <mripard@kernel.org> Link: https://lore.kernel.org/r/20250826063419.3022216-3-riana.tauro@intel.com Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
2025-08-26 12:04:09 +05:30
drm: Introduce device wedged event Introduce device wedged event, which notifies userspace of 'wedged' (hanged/unusable) state of the DRM device through a uevent. This is useful especially in cases where the device is no longer operating as expected and has become unrecoverable from driver context. Purpose of this implementation is to provide drivers a generic way to recover the device with the help of userspace intervention without taking any drastic measures (like resetting or re-enumerating the full bus, on which the underlying physical device is sitting) in the driver. A 'wedged' device is basically a device that is declared dead by the driver after exhausting all possible attempts to recover it from driver context. The uevent is the notification that is sent to userspace along with a hint about what could possibly be attempted to recover the device from userspace and bring it back to usable state. Different drivers may have different ideas of a 'wedged' device depending on hardware implementation of the underlying physical device, and hence the vendor agnostic nature of the event. It is up to the drivers to decide when they see the need for device recovery and how they want to recover from the available methods. Driver prerequisites -------------------- The driver, before opting for recovery, needs to make sure that the 'wedged' device doesn't harm the system as a whole by taking care of the prerequisites. Necessary actions must include disabling DMA to system memory as well as any communication channels with other devices. Further, the driver must ensure that all dma_fences are signalled and any device state that the core kernel might depend on is cleaned up. All existing mmaps should be invalidated and page faults should be redirected to a dummy page. Once the event is sent, the device must be kept in 'wedged' state until the recovery is performed. New accesses to the device (IOCTLs) should be rejected, preferably with an error code that resembles the type of failure the device has encountered. This will signify the reason for wedging, which can be reported to the application if needed. Recovery -------- Current implementation defines three recovery methods, out of which, drivers can use any one, multiple or none. Method(s) of choice will be sent in the uevent environment as ``WEDGED=<method1>[,..,<methodN>]`` in order of less to more side-effects. If driver is unsure about recovery or method is unknown (like soft/hard system reboot, firmware flashing, physical device replacement or any other procedure which can't be attempted on the fly), ``WEDGED=unknown`` will be sent instead. Userspace consumers can parse this event and attempt recovery as per the following expectations. =============== ======================================== Recovery method Consumer expectations =============== ======================================== none optional telemetry collection rebind unbind + bind driver bus-reset unbind + bus reset/re-enumeration + bind unknown consumer policy =============== ======================================== The only exception to this is ``WEDGED=none``, which signifies that the device was temporarily 'wedged' at some point but was recovered from driver context using device specific methods like reset. No explicit recovery is expected from the consumer in this case, but it can still take additional steps like gathering telemetry information (devcoredump, syslog). This is useful because the first hang is usually the most critical one which can result in consequential hangs or complete wedging. Consumer prerequisites ---------------------- It is the responsibility of the consumer to make sure that the device or its resources are not in use by any process before attempting recovery. With IOCTLs erroring out, all device memory should be unmapped and file descriptors should be closed to prevent leaks or undefined behaviour. The idea here is to clear the device of all user context beforehand and set the stage for a clean recovery. Example ------- Udev rule:: SUBSYSTEM=="drm", ENV{WEDGED}=="rebind", DEVPATH=="*/drm/card[0-9]", RUN+="/path/to/rebind.sh $env{DEVPATH}" Recovery script:: #!/bin/sh DEVPATH=$(readlink -f /sys/$1/device) DEVICE=$(basename $DEVPATH) DRIVER=$(readlink -f $DEVPATH/driver) echo -n $DEVICE > $DRIVER/unbind echo -n $DEVICE > $DRIVER/bind Customization ------------- Although basic recovery is possible with a simple script, consumers can define custom policies around recovery. For example, if the driver supports multiple recovery methods, consumers can opt for the suitable one depending on scenarios like repeat offences or vendor specific failures. Consumers can also choose to have the device available for debugging or telemetry collection and base their recovery decision on the findings. This is useful especially when the driver is unsure about recovery or method is unknown. v4: s/drm_dev_wedged/drm_dev_wedged_event Use drm_info() (Jani) Kernel doc adjustment (Aravind) v5: Send recovery method with uevent (Lina) v6: Access wedge_recovery_opts[] using helper function (Jani) Use snprintf() (Jani) v7: Convert recovery helpers into regular functions (Andy, Jani) Aesthetic adjustments (Andy) Handle invalid recovery method v8: Allow sending multiple methods with uevent (Lucas, Michal) static_assert() globally (Andy) v9: Provide 'none' method for device reset (Christian) Provide recovery opts using switch cases v11: Log device reset (André) Signed-off-by: Raag Jadav <raag.jadav@intel.com> Reviewed-by: André Almeida <andrealmeid@igalia.com> Reviewed-by: Christian König <christian.koenig@amd.com> Link: https://patchwork.freedesktop.org/patch/msgid/20250204070528.1919158-2-raag.jadav@intel.com Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
2025-02-04 12:35:24 +05:30
drm: Add a vendor-specific recovery method to drm device wedged uevent Address the need for a recovery method (firmware flash on Firmware errors) introduced in the later patches of Xe KMD. Whenever XE KMD detects a firmware error, a firmware flash is required to recover the device to normal operation. The initial proposal to use 'firmware-flash' as a recovery method was not applicable to other drivers and could cause multiple recovery methods specific to vendors to be added. To address this a more generic 'vendor-specific' method is introduced, guiding users to refer to vendor specific documentation and system logs for detailed vendor specific recovery procedure. Add a recovery method 'WEDGED=vendor-specific' for such errors. Vendors must provide additional recovery documentation if this method is used. It is the responsibility of the consumer to refer to the correct vendor specific documentation and usecase before attempting a recovery. For example: If driver is XE KMD, the consumer must refer to the documentation of 'Device Wedging' under 'Documentation/gpu/xe/'. v2: fix documentation (Raag) v3: add more details to commit message (Sima, Rodrigo, Raag) add an example script to the documentation (Raag) v4: use consistent naming (Raag) v5: fix commit message v6: add more documentation Cc: André Almeida <andrealmeid@igalia.com> Cc: Christian König <christian.koenig@amd.com> Cc: David Airlie <airlied@gmail.com> Cc: Simona Vetter <simona.vetter@ffwll.ch> Cc: Maxime Ripard <mripard@kernel.org> Signed-off-by: Riana Tauro <riana.tauro@intel.com> Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com> Acked-by: Maxime Ripard <mripard@kernel.org> Link: https://lore.kernel.org/r/20250826063419.3022216-3-riana.tauro@intel.com Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
2025-08-26 12:04:09 +05:30
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&egg 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. Reviewed-by: Sam Ravnborg <sam@ravnborg.org> Cc: Thomas Zimmermann <tzimmermann@suse.de> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Sam Ravnborg <sam@ravnborg.org> Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Cc: Neil Armstrong <narmstrong@baylibre.com Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20200324124540.3227396-1-daniel.vetter@ffwll.ch
2020-03-24 13:45:40 +01:00
drm: document better that drivers shouldn't use drm_minor directly The documentation for struct drm_minor already states this, but that's not always that easy to find. Also due to historical reasons we still have the minor-centric interfaces (like drm_debugfs_create_files), but since this is now getting fixed we can put a few more pointers in place as to how this should be done ideally. Note that debugfs isn't there yet for all cases (debugfs files on kms objects like crtc/connector aren't supported, neither debugfs files with full fops), so the debugfs side of this is still rather aspirational and more for new users than converting everything existing. todo.rst covers the additional work needed already. Motivated by some discussion with Rodrigo on irc about how drm/xe should lay out its sysfs interfaces. v2: Make the debugfs situation clearer in the commit message, but don't elaborate more in the actual kerneldoc to avoid distracting from the main message around sysfs (Jani) Also fix some typos. Acked-by: Rodrigo Vivi <rodrigo.vivi@intel.com> Reviewed-by: Melissa Wen <mwen@igalia.com> Reviewed-by: Maíra Canal <mcanal@igalia.com> Acked-by: Maxime Ripard <maxime@cerno.tech> Acked-by: Jani Nikula <jani.nikula@linux.intel.com> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Cc: Wambui Karuga <wambui.karugax@gmail.com> Cc: Maíra Canal <mcanal@igalia.com> Cc: Maxime Ripard <maxime@cerno.tech> Cc: Melissa Wen <mwen@igalia.com> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20230109164604.3860862-1-daniel.vetter@ffwll.ch
2023-01-09 17:46:04 +01:00
drm: document better that drivers shouldn't use drm_minor directly The documentation for struct drm_minor already states this, but that's not always that easy to find. Also due to historical reasons we still have the minor-centric interfaces (like drm_debugfs_create_files), but since this is now getting fixed we can put a few more pointers in place as to how this should be done ideally. Note that debugfs isn't there yet for all cases (debugfs files on kms objects like crtc/connector aren't supported, neither debugfs files with full fops), so the debugfs side of this is still rather aspirational and more for new users than converting everything existing. todo.rst covers the additional work needed already. Motivated by some discussion with Rodrigo on irc about how drm/xe should lay out its sysfs interfaces. v2: Make the debugfs situation clearer in the commit message, but don't elaborate more in the actual kerneldoc to avoid distracting from the main message around sysfs (Jani) Also fix some typos. Acked-by: Rodrigo Vivi <rodrigo.vivi@intel.com> Reviewed-by: Melissa Wen <mwen@igalia.com> Reviewed-by: Maíra Canal <mcanal@igalia.com> Acked-by: Maxime Ripard <maxime@cerno.tech> Acked-by: Jani Nikula <jani.nikula@linux.intel.com> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Cc: Wambui Karuga <wambui.karugax@gmail.com> Cc: Maíra Canal <mcanal@igalia.com> Cc: Maxime Ripard <maxime@cerno.tech> Cc: Melissa Wen <mwen@igalia.com> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20230109164604.3860862-1-daniel.vetter@ffwll.ch
2023-01-09 17:46:04 +01:00
accel: add dedicated minor for accelerator devices The accelerator devices are exposed to user-space using a dedicated major. In addition, they are represented in /dev with new, dedicated device char names: /dev/accel/accel*. This is done to make sure any user-space software that tries to open a graphic card won't open the accelerator device by mistake. The above implies that the minor numbering should be separated from the rest of the DRM devices. However, to avoid code duplication, we want the drm_minor structure to be able to represent the accelerator device. To achieve this, we add a new drm_minor* to drm_device that represents the accelerator device. This pointer is initialized for drivers that declare they handle compute accelerator, using a new driver feature flag called DRIVER_COMPUTE_ACCEL. It is important to note that this driver feature is mutually exclusive with DRIVER_RENDER. Devices that want to expose both graphics and compute device char files should be handled by two drivers that are connected using the auxiliary bus framework. In addition, we define a different IDR to handle the accelerators minors. This is done to make the minor's index be identical to the device index in /dev/. Any access to the IDR is done solely by functions in accel_drv.c, as the IDR is define as static. The DRM core functions call those functions in case they detect the minor's type is DRM_MINOR_ACCEL. We define a separate accel_open function (from drm_open) that the accel drivers should set as their open callback function. Both these functions eventually call the same drm_open_helper(), which had to be changed to be non-static so it can be called from accel_drv.c. accel_open() only partially duplicates drm_open as I removed some code from it that handles legacy devices. To help new drivers, I defined DEFINE_DRM_ACCEL_FOPS macro to easily set the required function operations pointers structure. Signed-off-by: Oded Gabbay <ogabbay@kernel.org> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Jeffrey Hugo <quic_jhugo@quicinc.com> Reviewed-by: Dave Airlie <airlied@redhat.com> Acked-by: Thomas Zimmermann <tzimmermann@suse.de> Acked-by: Jacek Lawrynowicz <jacek.lawrynowicz@linux.intel.com> Tested-by: Jacek Lawrynowicz <jacek.lawrynowicz@linux.intel.com> Reviewed-by: Melissa Wen <mwen@igalia.com>
2022-10-31 15:33:06 +02:00
drm/gem: Add huge tmpfs mountpoint helpers Add the drm_gem_huge_mnt_create() and drm_gem_get_huge_mnt() helpers to avoid code duplication in the i915, V3D, Panfrost and Panthor drivers. The former creates and mounts a dedicated huge tmpfs mountpoint, for the lifetime of a DRM device, used at GEM object initialization. The latter retrieves the dedicated huge tmpfs mountpoint used by a DRM device. The next commits will port drivers to these helpers. v3: - store huge tmpfs mountpoint in drm_device v4: - return 0 in builds with CONFIG_TRANSPARENT_HUGEPAGE=n - return 0 when huge_mnt already exists - use new vfs_parse_fs_string() helper v5: - remove warning on !dev->huge_mnt and reset to NULL on free - inline drm_gem_huge_mnt_create() to remove func from text and avoid calls in builds with CONFIG_TRANSPARENT_HUGEPAGE=n - compile out drm_device's huge_mnt field in builds with CONFIG_TRANSPARENT_HUGEPAGE=n - add drm_gem_has_huge_mnt() helper v6: - move huge_mnt doc into ifdef'd section - either inline or export drm_gem_huge_mnt_create() v7: - include <drm/drm_device.h> in drm_gem.h v9: - replace drm_gem_has_huge_mnt() by drm_gem_get_huge_mnt() v11: - doc fixes - add Boris and Maíra R-bs Signed-off-by: Loïc Molinari <loic.molinari@collabora.com> Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com> Reviewed-by: Maíra Canal <mcanal@igalia.com> Link: https://patch.msgid.link/20251205182231.194072-5-loic.molinari@collabora.com Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
2025-12-05 19:22:25 +01:00
drm/gem: Make the GEM LRU lock part of drm_device Recently, a few races have been discovered in the GEM LRU logic, all of them caused by the fact the LRU lock is accessed through gem->lru->lock, and that very same lock also protects changes to gem->lru, leading to situations where gem->lru needs to first be accessed without the lock held, to then get the lru to access the lock through and finally take the lock and do the expected operation. Currently, the only driver making use of this API (MSM) declares a device-wide lock, and the user we're about to add (panthor) will do the same. There's no evidence that we will ever have a driver that wants different pools of LRUs protected by different locks under the same drm_device. So we're better off moving this lock to drm_device and always locking it through obj->dev->gem_lru_mutex, or directly through dev->gem_lru_mutex. If anyone ever needs more fine-grained locking, this can be revisited to pass some drm_gem_lru_pool object representing the pool of LRUs under a specific lock, but for now, the per-device lock seems to be enough. Fixes: e7c2af13f811 ("drm/gem: Add LRU/shrinker helper") Reported-by: Chia-I Wu <olvaffe@gmail.com> Closes: https://gitlab.freedesktop.org/panfrost/linux/-/work_items/86 Reviewed-by: Rob Clark <rob.clark@oss.qualcomm.com> Reviewed-by: Liviu Dudau <liviu.dudau@arm.com> Reviewed-by: Steven Price <steven.price@arm.com> Reviewed-by: Chia-I Wu <olvaffe@gmail.com> Link: https://patch.msgid.link/20260518-panthor-shrinker-fixes-v4-1-1920234470d5@collabora.com Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
2026-05-18 13:41:45 +02:00