Hi, Christian. On Thu, 2024-07-11 at 14:01 +0200, Christian König wrote: > Am 10.07.24 um 20:19 schrieb Matthew Brost: > > On Wed, Jul 10, 2024 at 02:42:58PM +0200, Christian König wrote: > > > That is something drivers really shouldn't mess with. > > > > > Thomas uses this in Xe to implement a shrinker [1]. Seems to need > > to > > remain available for drivers. > > No, that is exactly what I try to prevent with that. > > This is an internally thing of TTM and drivers should never use it > directly. That driver-facing LRU walker is a direct response/solution to this comment that you made in the first shrinker series: https://lore.kernel.org/linux-mm/b7491378-defd-4f1c-31e2-29e4c77e2d67@xxxxxxx/T/#ma918844aa8a6efe8768fdcda0c6590d5c93850c9 That is also mentioned in the cover letter of the recent shrinker series, and this walker has been around in that shrinker series for more than half a year now so if you think it's not the correct driver facing API IMHO that should be addressed by a review comment in that series rather than in posting a conflicting patch? So assuming that we still want the driver to register the shrinker, IMO that helper abstracts away all the nasty locking and pitfalls for a driver-registered shrinker, and is similar in structure to for example the pagewalk helper in mm/pagewalk.c. An alternative that could be tried as a driver-facing API is to provide a for_each_bo_in_lru_lock() macro where the driver open-codes "process_bo()" inside the for loop but I tried this and found it quite fragile since the driver might exit the loop without performing the necessary cleanup. However with using scoped_guard() in linux/cleanup.h that could probably be mitigated to some exent, but I still think that a walker helper like this is the safer choice and given the complexity of a for_ macro involving scoped_guard(), I think the walker helper is the easiest-to-maintain solution moving forward. But open to suggestions. Thanks Thomas > > Regards, > Christian. > > > > > Matt > > > > [1] > > https://patchwork.freedesktop.org/patch/602165/?series=131815&rev=6 > > > > > Signed-off-by: Christian König <christian.koenig@xxxxxxx> > > > --- > > > drivers/gpu/drm/ttm/ttm_bo.c | 1 + > > > drivers/gpu/drm/ttm/ttm_bo_util.c | 2 + > > > drivers/gpu/drm/ttm/ttm_bo_util.h | 67 > > > +++++++++++++++++++++++++++++++ > > > include/drm/ttm/ttm_bo.h | 35 ---------------- > > > 4 files changed, 70 insertions(+), 35 deletions(-) > > > create mode 100644 drivers/gpu/drm/ttm/ttm_bo_util.h > > > > > > diff --git a/drivers/gpu/drm/ttm/ttm_bo.c > > > b/drivers/gpu/drm/ttm/ttm_bo.c > > > index 0131ec802066..41bee8696e69 100644 > > > --- a/drivers/gpu/drm/ttm/ttm_bo.c > > > +++ b/drivers/gpu/drm/ttm/ttm_bo.c > > > @@ -45,6 +45,7 @@ > > > #include <linux/dma-resv.h> > > > > > > #include "ttm_module.h" > > > +#include "ttm_bo_util.h" > > > > > > static void ttm_bo_mem_space_debug(struct ttm_buffer_object > > > *bo, > > > struct ttm_placement > > > *placement) > > > diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c > > > b/drivers/gpu/drm/ttm/ttm_bo_util.c > > > index 3c07f4712d5c..03e28e3d0d03 100644 > > > --- a/drivers/gpu/drm/ttm/ttm_bo_util.c > > > +++ b/drivers/gpu/drm/ttm/ttm_bo_util.c > > > @@ -37,6 +37,8 @@ > > > > > > #include <drm/drm_cache.h> > > > > > > +#include "ttm_bo_util.h" > > > + > > > struct ttm_transfer_obj { > > > struct ttm_buffer_object base; > > > struct ttm_buffer_object *bo; > > > diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.h > > > b/drivers/gpu/drm/ttm/ttm_bo_util.h > > > new file mode 100644 > > > index 000000000000..c19b50809208 > > > --- /dev/null > > > +++ b/drivers/gpu/drm/ttm/ttm_bo_util.h > > > @@ -0,0 +1,67 @@ > > > +/* SPDX-License-Identifier: GPL-2.0 OR MIT */ > > > +/*************************************************************** > > > *********** > > > + * Copyright 2024 Advanced Micro Devices, Inc. > > > + * > > > + * Permission is hereby granted, free of charge, to any person > > > obtaining a > > > + * copy of this software and associated documentation files (the > > > "Software"), > > > + * to deal in the Software without restriction, including > > > without limitation > > > + * the rights to use, copy, modify, merge, publish, distribute, > > > sublicense, > > > + * and/or sell copies of the Software, and to permit persons to > > > whom the > > > + * Software is furnished to do so, subject to the following > > > conditions: > > > + * > > > + * The above copyright notice and this permission notice shall > > > be included in > > > + * all copies or substantial portions of the Software. > > > + * > > > + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY > > > KIND, EXPRESS OR > > > + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF > > > MERCHANTABILITY, > > > + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO > > > EVENT SHALL > > > + * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, > > > DAMAGES OR > > > + * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR > > > OTHERWISE, > > > + * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR > > > THE USE OR > > > + * OTHER DEALINGS IN THE SOFTWARE. > > > + * > > > + > > > ***************************************************************** > > > *********/ > > > +#ifndef _TTM_BO_UTIL_H_ > > > +#define _TTM_BO_UTIL_H_ > > > + > > > +struct ww_acquire_ctx; > > > + > > > +struct ttm_buffer_object; > > > +struct ttm_operation_ctx; > > > +struct ttm_lru_walk; > > > + > > > +/** struct ttm_lru_walk_ops - Operations for a LRU walk. */ > > > +struct ttm_lru_walk_ops { > > > + /** > > > + * process_bo - Process this bo. > > > + * @walk: struct ttm_lru_walk describing the walk. > > > + * @bo: A locked and referenced buffer object. > > > + * > > > + * Return: Negative error code on error, User-defined > > > positive value > > > + * (typically, but not always, size of the processed bo) > > > on success. > > > + * On success, the returned values are summed by the > > > walk and the > > > + * walk exits when its target is met. > > > + * 0 also indicates success, -EBUSY means this bo was > > > skipped. > > > + */ > > > + s64 (*process_bo)(struct ttm_lru_walk *walk, > > > + struct ttm_buffer_object *bo); > > > +}; > > > + > > > +/** > > > + * struct ttm_lru_walk - Structure describing a LRU walk. > > > + */ > > > +struct ttm_lru_walk { > > > + /** @ops: Pointer to the ops structure. */ > > > + const struct ttm_lru_walk_ops *ops; > > > + /** @ctx: Pointer to the struct ttm_operation_ctx. */ > > > + struct ttm_operation_ctx *ctx; > > > + /** @ticket: The struct ww_acquire_ctx if any. */ > > > + struct ww_acquire_ctx *ticket; > > > + /** @tryock_only: Only use trylock for locking. */ > > > + bool trylock_only; > > > +}; > > > + > > > +s64 ttm_lru_walk_for_evict(struct ttm_lru_walk *walk, struct > > > ttm_device *bdev, > > > + struct ttm_resource_manager *man, s64 > > > target); > > > + > > > +#endif > > > diff --git a/include/drm/ttm/ttm_bo.h b/include/drm/ttm/ttm_bo.h > > > index d1a732d56259..5f7c967222a2 100644 > > > --- a/include/drm/ttm/ttm_bo.h > > > +++ b/include/drm/ttm/ttm_bo.h > > > @@ -194,41 +194,6 @@ struct ttm_operation_ctx { > > > uint64_t bytes_moved; > > > }; > > > > > > -struct ttm_lru_walk; > > > - > > > -/** struct ttm_lru_walk_ops - Operations for a LRU walk. */ > > > -struct ttm_lru_walk_ops { > > > - /** > > > - * process_bo - Process this bo. > > > - * @walk: struct ttm_lru_walk describing the walk. > > > - * @bo: A locked and referenced buffer object. > > > - * > > > - * Return: Negative error code on error, User-defined > > > positive value > > > - * (typically, but not always, size of the processed bo) > > > on success. > > > - * On success, the returned values are summed by the > > > walk and the > > > - * walk exits when its target is met. > > > - * 0 also indicates success, -EBUSY means this bo was > > > skipped. > > > - */ > > > - s64 (*process_bo)(struct ttm_lru_walk *walk, struct > > > ttm_buffer_object *bo); > > > -}; > > > - > > > -/** > > > - * struct ttm_lru_walk - Structure describing a LRU walk. > > > - */ > > > -struct ttm_lru_walk { > > > - /** @ops: Pointer to the ops structure. */ > > > - const struct ttm_lru_walk_ops *ops; > > > - /** @ctx: Pointer to the struct ttm_operation_ctx. */ > > > - struct ttm_operation_ctx *ctx; > > > - /** @ticket: The struct ww_acquire_ctx if any. */ > > > - struct ww_acquire_ctx *ticket; > > > - /** @tryock_only: Only use trylock for locking. */ > > > - bool trylock_only; > > > -}; > > > - > > > -s64 ttm_lru_walk_for_evict(struct ttm_lru_walk *walk, struct > > > ttm_device *bdev, > > > - struct ttm_resource_manager *man, s64 > > > target); > > > - > > > /** > > > * ttm_bo_get - reference a struct ttm_buffer_object > > > * > > > -- > > > 2.34.1 > > > >
