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    Subject[PATCH v6 22/22] drm/panfrost: Switch to generic memory shrinker
    Date
    Replace Panfrost's memory shrinker with a generic drm-shmem memory
    shrinker.

    Tested-by: Steven Price <steven.price@arm.com>
    Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
    ---
    drivers/gpu/drm/panfrost/Makefile | 1 -
    drivers/gpu/drm/panfrost/panfrost_device.h | 4 -
    drivers/gpu/drm/panfrost/panfrost_drv.c | 19 +--
    drivers/gpu/drm/panfrost/panfrost_gem.c | 33 +++--
    drivers/gpu/drm/panfrost/panfrost_gem.h | 9 --
    .../gpu/drm/panfrost/panfrost_gem_shrinker.c | 129 ------------------
    drivers/gpu/drm/panfrost/panfrost_job.c | 18 ++-
    7 files changed, 42 insertions(+), 171 deletions(-)
    delete mode 100644 drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c

    diff --git a/drivers/gpu/drm/panfrost/Makefile b/drivers/gpu/drm/panfrost/Makefile
    index b71935862417..ecf0864cb515 100644
    --- a/drivers/gpu/drm/panfrost/Makefile
    +++ b/drivers/gpu/drm/panfrost/Makefile
    @@ -5,7 +5,6 @@ panfrost-y := \
    panfrost_device.o \
    panfrost_devfreq.o \
    panfrost_gem.o \
    - panfrost_gem_shrinker.o \
    panfrost_gpu.o \
    panfrost_job.o \
    panfrost_mmu.o \
    diff --git a/drivers/gpu/drm/panfrost/panfrost_device.h b/drivers/gpu/drm/panfrost/panfrost_device.h
    index 8b25278f34c8..fe04b21fc044 100644
    --- a/drivers/gpu/drm/panfrost/panfrost_device.h
    +++ b/drivers/gpu/drm/panfrost/panfrost_device.h
    @@ -115,10 +115,6 @@ struct panfrost_device {
    atomic_t pending;
    } reset;

    - struct mutex shrinker_lock;
    - struct list_head shrinker_list;
    - struct shrinker shrinker;
    -
    struct panfrost_devfreq pfdevfreq;
    };

    diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c b/drivers/gpu/drm/panfrost/panfrost_drv.c
    index 859e240161d1..b77c99ba2475 100644
    --- a/drivers/gpu/drm/panfrost/panfrost_drv.c
    +++ b/drivers/gpu/drm/panfrost/panfrost_drv.c
    @@ -160,7 +160,6 @@ panfrost_lookup_bos(struct drm_device *dev,
    break;
    }

    - atomic_inc(&bo->gpu_usecount);
    job->mappings[i] = mapping;
    }

    @@ -392,7 +391,6 @@ static int panfrost_ioctl_madvise(struct drm_device *dev, void *data,
    {
    struct panfrost_file_priv *priv = file_priv->driver_priv;
    struct drm_panfrost_madvise *args = data;
    - struct panfrost_device *pfdev = dev->dev_private;
    struct drm_gem_object *gem_obj;
    struct panfrost_gem_object *bo;
    int ret = 0;
    @@ -409,7 +407,6 @@ static int panfrost_ioctl_madvise(struct drm_device *dev, void *data,
    if (ret)
    goto out_put_object;

    - mutex_lock(&pfdev->shrinker_lock);
    mutex_lock(&bo->mappings.lock);
    if (args->madv == PANFROST_MADV_DONTNEED) {
    struct panfrost_gem_mapping *first;
    @@ -435,17 +432,8 @@ static int panfrost_ioctl_madvise(struct drm_device *dev, void *data,

    args->retained = drm_gem_shmem_madvise(&bo->base, args->madv);

    - if (args->retained) {
    - if (args->madv == PANFROST_MADV_DONTNEED)
    - list_move_tail(&bo->base.madv_list,
    - &pfdev->shrinker_list);
    - else if (args->madv == PANFROST_MADV_WILLNEED)
    - list_del_init(&bo->base.madv_list);
    - }
    -
    out_unlock_mappings:
    mutex_unlock(&bo->mappings.lock);
    - mutex_unlock(&pfdev->shrinker_lock);
    dma_resv_unlock(bo->base.base.resv);
    out_put_object:
    drm_gem_object_put(gem_obj);
    @@ -577,9 +565,6 @@ static int panfrost_probe(struct platform_device *pdev)
    ddev->dev_private = pfdev;
    pfdev->ddev = ddev;

    - mutex_init(&pfdev->shrinker_lock);
    - INIT_LIST_HEAD(&pfdev->shrinker_list);
    -
    err = panfrost_device_init(pfdev);
    if (err) {
    if (err != -EPROBE_DEFER)
    @@ -601,7 +586,7 @@ static int panfrost_probe(struct platform_device *pdev)
    if (err < 0)
    goto err_out1;

    - panfrost_gem_shrinker_init(ddev);
    + drm_gem_shmem_shrinker_register(ddev);

    return 0;

    @@ -619,8 +604,8 @@ static int panfrost_remove(struct platform_device *pdev)
    struct panfrost_device *pfdev = platform_get_drvdata(pdev);
    struct drm_device *ddev = pfdev->ddev;

    + drm_gem_shmem_shrinker_unregister(ddev);
    drm_dev_unregister(ddev);
    - panfrost_gem_shrinker_cleanup(ddev);

    pm_runtime_get_sync(pfdev->dev);
    pm_runtime_disable(pfdev->dev);
    diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.c b/drivers/gpu/drm/panfrost/panfrost_gem.c
    index 293e799e2fe8..f1436405e3a0 100644
    --- a/drivers/gpu/drm/panfrost/panfrost_gem.c
    +++ b/drivers/gpu/drm/panfrost/panfrost_gem.c
    @@ -19,16 +19,6 @@ static void panfrost_gem_free_object(struct drm_gem_object *obj)
    struct panfrost_gem_object *bo = to_panfrost_bo(obj);
    struct panfrost_device *pfdev = obj->dev->dev_private;

    - /*
    - * Make sure the BO is no longer inserted in the shrinker list before
    - * taking care of the destruction itself. If we don't do that we have a
    - * race condition between this function and what's done in
    - * panfrost_gem_shrinker_scan().
    - */
    - mutex_lock(&pfdev->shrinker_lock);
    - list_del_init(&bo->base.madv_list);
    - mutex_unlock(&pfdev->shrinker_lock);
    -
    /*
    * If we still have mappings attached to the BO, there's a problem in
    * our refcounting.
    @@ -209,6 +199,25 @@ static const struct drm_gem_object_funcs panfrost_gem_funcs = {
    .vm_ops = &drm_gem_shmem_vm_ops,
    };

    +static int panfrost_shmem_evict(struct drm_gem_shmem_object *shmem)
    +{
    + struct panfrost_gem_object *bo = to_panfrost_bo(&shmem->base);
    +
    + if (!drm_gem_shmem_is_purgeable(shmem))
    + return -EOPNOTSUPP;
    +
    + if (!mutex_trylock(&bo->mappings.lock))
    + return -EBUSY;
    +
    + panfrost_gem_teardown_mappings_locked(bo);
    +
    + drm_gem_shmem_purge(shmem);
    +
    + mutex_unlock(&bo->mappings.lock);
    +
    + return 0;
    +}
    +
    /**
    * panfrost_gem_create_object - Implementation of driver->gem_create_object.
    * @dev: DRM device
    @@ -230,6 +239,7 @@ struct drm_gem_object *panfrost_gem_create_object(struct drm_device *dev, size_t
    mutex_init(&obj->mappings.lock);
    obj->base.base.funcs = &panfrost_gem_funcs;
    obj->base.map_wc = !pfdev->coherent;
    + obj->base.evict = panfrost_shmem_evict;

    return &obj->base.base;
    }
    @@ -266,6 +276,9 @@ panfrost_gem_create_with_handle(struct drm_file *file_priv,
    if (ret)
    return ERR_PTR(ret);

    + if (!bo->is_heap)
    + drm_gem_shmem_set_purgeable(shmem);
    +
    return bo;
    }

    diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.h b/drivers/gpu/drm/panfrost/panfrost_gem.h
    index 8088d5fd8480..09da064f1c07 100644
    --- a/drivers/gpu/drm/panfrost/panfrost_gem.h
    +++ b/drivers/gpu/drm/panfrost/panfrost_gem.h
    @@ -30,12 +30,6 @@ struct panfrost_gem_object {
    struct mutex lock;
    } mappings;

    - /*
    - * Count the number of jobs referencing this BO so we don't let the
    - * shrinker reclaim this object prematurely.
    - */
    - atomic_t gpu_usecount;
    -
    bool noexec :1;
    bool is_heap :1;
    };
    @@ -84,7 +78,4 @@ panfrost_gem_mapping_get(struct panfrost_gem_object *bo,
    void panfrost_gem_mapping_put(struct panfrost_gem_mapping *mapping);
    void panfrost_gem_teardown_mappings_locked(struct panfrost_gem_object *bo);

    -void panfrost_gem_shrinker_init(struct drm_device *dev);
    -void panfrost_gem_shrinker_cleanup(struct drm_device *dev);
    -
    #endif /* __PANFROST_GEM_H__ */
    diff --git a/drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c b/drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c
    deleted file mode 100644
    index 7cc32556f908..000000000000
    --- a/drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c
    +++ /dev/null
    @@ -1,129 +0,0 @@
    -// SPDX-License-Identifier: GPL-2.0
    -/* Copyright (C) 2019 Arm Ltd.
    - *
    - * Based on msm_gem_freedreno.c:
    - * Copyright (C) 2016 Red Hat
    - * Author: Rob Clark <robdclark@gmail.com>
    - */
    -
    -#include <linux/list.h>
    -
    -#include <drm/drm_device.h>
    -#include <drm/drm_gem_shmem_helper.h>
    -
    -#include "panfrost_device.h"
    -#include "panfrost_gem.h"
    -#include "panfrost_mmu.h"
    -
    -static bool panfrost_gem_shmem_is_purgeable(struct drm_gem_shmem_object *shmem)
    -{
    - return (shmem->madv > 0) &&
    - !shmem->pages_pin_count && shmem->sgt &&
    - !shmem->base.dma_buf && !shmem->base.import_attach;
    -}
    -
    -static unsigned long
    -panfrost_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc)
    -{
    - struct panfrost_device *pfdev =
    - container_of(shrinker, struct panfrost_device, shrinker);
    - struct drm_gem_shmem_object *shmem;
    - unsigned long count = 0;
    -
    - if (!mutex_trylock(&pfdev->shrinker_lock))
    - return 0;
    -
    - list_for_each_entry(shmem, &pfdev->shrinker_list, madv_list) {
    - if (panfrost_gem_shmem_is_purgeable(shmem))
    - count += shmem->base.size >> PAGE_SHIFT;
    - }
    -
    - mutex_unlock(&pfdev->shrinker_lock);
    -
    - return count;
    -}
    -
    -static bool panfrost_gem_purge(struct drm_gem_object *obj)
    -{
    - struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
    - struct panfrost_gem_object *bo = to_panfrost_bo(obj);
    - bool ret = false;
    -
    - if (atomic_read(&bo->gpu_usecount))
    - return false;
    -
    - if (!mutex_trylock(&bo->mappings.lock))
    - return false;
    -
    - if (!dma_resv_trylock(shmem->base.resv))
    - goto unlock_mappings;
    -
    - panfrost_gem_teardown_mappings_locked(bo);
    - drm_gem_shmem_purge(&bo->base);
    - ret = true;
    -
    - dma_resv_unlock(shmem->base.resv);
    -
    -unlock_mappings:
    - mutex_unlock(&bo->mappings.lock);
    - return ret;
    -}
    -
    -static unsigned long
    -panfrost_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc)
    -{
    - struct panfrost_device *pfdev =
    - container_of(shrinker, struct panfrost_device, shrinker);
    - struct drm_gem_shmem_object *shmem, *tmp;
    - unsigned long freed = 0;
    -
    - if (!mutex_trylock(&pfdev->shrinker_lock))
    - return SHRINK_STOP;
    -
    - list_for_each_entry_safe(shmem, tmp, &pfdev->shrinker_list, madv_list) {
    - if (freed >= sc->nr_to_scan)
    - break;
    - if (drm_gem_shmem_is_purgeable(shmem) &&
    - panfrost_gem_purge(&shmem->base)) {
    - freed += shmem->base.size >> PAGE_SHIFT;
    - list_del_init(&shmem->madv_list);
    - }
    - }
    -
    - mutex_unlock(&pfdev->shrinker_lock);
    -
    - if (freed > 0)
    - pr_info_ratelimited("Purging %lu bytes\n", freed << PAGE_SHIFT);
    -
    - return freed;
    -}
    -
    -/**
    - * panfrost_gem_shrinker_init - Initialize panfrost shrinker
    - * @dev: DRM device
    - *
    - * This function registers and sets up the panfrost shrinker.
    - */
    -void panfrost_gem_shrinker_init(struct drm_device *dev)
    -{
    - struct panfrost_device *pfdev = dev->dev_private;
    - pfdev->shrinker.count_objects = panfrost_gem_shrinker_count;
    - pfdev->shrinker.scan_objects = panfrost_gem_shrinker_scan;
    - pfdev->shrinker.seeks = DEFAULT_SEEKS;
    - WARN_ON(register_shrinker(&pfdev->shrinker));
    -}
    -
    -/**
    - * panfrost_gem_shrinker_cleanup - Clean up panfrost shrinker
    - * @dev: DRM device
    - *
    - * This function unregisters the panfrost shrinker.
    - */
    -void panfrost_gem_shrinker_cleanup(struct drm_device *dev)
    -{
    - struct panfrost_device *pfdev = dev->dev_private;
    -
    - if (pfdev->shrinker.nr_deferred) {
    - unregister_shrinker(&pfdev->shrinker);
    - }
    -}
    diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c
    index 7c4208476fbd..5c327a79455f 100644
    --- a/drivers/gpu/drm/panfrost/panfrost_job.c
    +++ b/drivers/gpu/drm/panfrost/panfrost_job.c
    @@ -271,6 +271,19 @@ static void panfrost_attach_object_fences(struct drm_gem_object **bos,
    dma_resv_add_fence(bos[i]->resv, fence, DMA_RESV_USAGE_WRITE);
    }

    +static int panfrost_objects_prepare(struct drm_gem_object **bos, int bo_count)
    +{
    + struct panfrost_gem_object *bo;
    + int ret = 0;
    +
    + while (!ret && bo_count--) {
    + bo = to_panfrost_bo(bos[bo_count]);
    + ret = bo->base.madv ? -ENOMEM : 0;
    + }
    +
    + return ret;
    +}
    +
    int panfrost_job_push(struct panfrost_job *job)
    {
    struct panfrost_device *pfdev = job->pfdev;
    @@ -282,6 +295,10 @@ int panfrost_job_push(struct panfrost_job *job)
    if (ret)
    return ret;

    + ret = panfrost_objects_prepare(job->bos, job->bo_count);
    + if (ret)
    + goto unlock;
    +
    mutex_lock(&pfdev->sched_lock);
    drm_sched_job_arm(&job->base);

    @@ -323,7 +340,6 @@ static void panfrost_job_cleanup(struct kref *ref)
    if (!job->mappings[i])
    break;

    - atomic_dec(&job->mappings[i]->obj->gpu_usecount);
    panfrost_gem_mapping_put(job->mappings[i]);
    }
    kvfree(job->mappings);
    --
    2.35.3
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