[Intel-gfx] [RFC PATCH 2/4] drm/cgroup: Add memory accounting to DRM cgroup
Maarten Lankhorst
maarten.lankhorst at linux.intel.com
Wed May 3 15:33:42 UTC 2023
On 2023-05-03 17:31, Tvrtko Ursulin wrote:
>
> On 03/05/2023 09:34, Maarten Lankhorst wrote:
>> Based roughly on the rdma and misc cgroup controllers, with a lot of
>> the accounting code borrowed from rdma.
>>
>> The interface is simple:
>> - populate drmcgroup_device->regions[..] name and size for each active
>> region.
>> - Call drm(m)cg_register_device()
>> - Use drmcg_try_charge to check if you can allocate a chunk of memory,
>> use drmcg_uncharge when freeing it. This may return an error code,
>> or -EAGAIN when the cgroup limit is reached.
>>
>> The ttm code transforms -EAGAIN back to -ENOSPC since it has specific
>> logic for -ENOSPC, and returning -EAGAIN to userspace causes drmIoctl
>> to restart infinitely.
>>
>> This API allows you to limit stuff with cgroups.
>> You can see the supported cards in /sys/fs/cgroup/drm.capacity
>> You need to echo +drm to cgroup.subtree_control, and then you can
>> partition memory.
>>
>> In each cgroup subdir:
>> drm.max shows the current limits of the cgroup.
>> drm.current the current amount of allocated memory used by this cgroup.
>> drm.events shows the amount of time max memory was reached.
>
> Events is not in the patch?
Oops, correct.
I removed it since it added more complexity, and didn't seem granular
enough to be useful.
I removed it from the documentation, but not the commit message it seems. :)
>
>> Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
>> ---
>> Documentation/admin-guide/cgroup-v2.rst | 46 ++
>> Documentation/gpu/drm-compute.rst | 54 +++
>> include/linux/cgroup_drm.h | 81 ++++
>> kernel/cgroup/drm.c | 539 +++++++++++++++++++++++-
>> 4 files changed, 699 insertions(+), 21 deletions(-)
>> create mode 100644 Documentation/gpu/drm-compute.rst
>>
>> diff --git a/Documentation/admin-guide/cgroup-v2.rst
>> b/Documentation/admin-guide/cgroup-v2.rst
>> index f67c0829350b..b858d99cb2ef 100644
>> --- a/Documentation/admin-guide/cgroup-v2.rst
>> +++ b/Documentation/admin-guide/cgroup-v2.rst
>> @@ -2374,6 +2374,52 @@ RDMA Interface Files
>> mlx4_0 hca_handle=1 hca_object=20
>> ocrdma1 hca_handle=1 hca_object=23
>> +DRM
>> +----
>> +
>> +The "drm" controller regulates the distribution and accounting of
>> +DRM resources.
>> +
>> +DRM Interface Files
>> +~~~~~~~~~~~~~~~~~~~~
>> +
>> + drm.max
>> + A readwrite nested-keyed file that exists for all the cgroups
>> + except root that describes current configured resource limit
>> + for a DRM device.
>> +
>> + Lines are keyed by device name and are not ordered.
>> + Each line contains space separated resource name and its configured
>> + limit that can be distributed.
>> +
>> + The following nested keys are defined.
>> +
>> + ==========
>> =======================================================
>> + region.* Maximum amount of bytes that allocatable in this
>> region
>> + ==========
>> =======================================================
>> +
>> + An example for xe follows::
>> +
>> + 0000:03:00.0 region.vram0=1073741824 region.stolen=max
>> +
>> + drm.capacity
>> + A read-only file that describes maximum region capacity.
>> + It only exists on the root cgroup. Not all memory can be
>> + allocated by cgroups, as the kernel reserves some for
>> + internal use.
>> +
>> + An example for xe follows::
>> +
>> + 0000:03:00.0 region.vram0=8514437120 region.stolen=67108864
>> +
>> + drm.current
>> + A read-only file that describes current resource usage.
>> + It exists for all the cgroup except root.
>> +
>> + An example for xe follows::
>> +
>> + 0000:03:00.0 region.vram0=12550144 region.stolen=8650752
>> +
>> HugeTLB
>> -------
>> diff --git a/Documentation/gpu/drm-compute.rst
>> b/Documentation/gpu/drm-compute.rst
>> new file mode 100644
>> index 000000000000..116270976ef7
>> --- /dev/null
>> +++ b/Documentation/gpu/drm-compute.rst
>> @@ -0,0 +1,54 @@
>> +==================================
>> +Long running workloads and compute
>> +==================================
>> +
>> +Long running workloads (compute) are workloads that will not
>> complete in 10
>> +seconds. (The time let the user wait before he reaches for the power
>> button).
>> +This means that other techniques need to be used to manage those
>> workloads,
>> +that cannot use fences.
>> +
>> +Some hardware may schedule compute jobs, and have no way to pre-empt
>> them, or
>> +have their memory swapped out from them. Or they simply want their
>> workload
>> +not to be preempted or swapped out at all.
>> +
>> +This means that it differs from what is described in
>> driver-api/dma-buf.rst.
>> +
>> +As with normal compute jobs, dma-fence may not be used at all. In
>> this case,
>> +not even to force preemption. The driver with is simply forced to
>> unmap a BO
>> +from the long compute job's address space on unbind immediately, not
>> even
>> +waiting for the workload to complete. Effectively this terminates
>> the workload
>> +when there is no hardware support to recover.
>> +
>> +Since this is undesirable, there need to be mitigations to prevent a
>> workload
>> +from being terminated. There are several possible approach, all with
>> their
>> +advantages and drawbacks.
>> +
>> +The first approach you will likely try is to pin all buffers used by
>> compute.
>> +This guarantees that the job will run uninterrupted, but also allows
>> a very
>> +denial of service attack by pinning as much memory as possible,
>> hogging the
>> +all GPU memory, and possibly a huge chunk of CPU memory.
>> +
>> +A second approach that will work slightly better on its own is
>> adding an option
>> +not to evict when creating a new job (any kind). If all of userspace
>> opts in
>> +to this flag, it would prevent cooperating userspace from forced
>> terminating
>> +older compute jobs to start a new one.
>> +
>> +If job preemption and recoverable pagefaults are not available,
>> those are the
>> +only approaches possible. So even with those, you want a separate
>> way of
>> +controlling resources. The standard kernel way of doing so is cgroups.
>> +
>> +This creates a third option, using cgroups to prevent eviction. Both
>> GPU and
>> +driver-allocated CPU memory would be accounted to the correct
>> cgroup, and
>> +eviction would be made cgroup aware. This allows the GPU to be
>> partitioned
>> +into cgroups, that will allow jobs to run next to each other without
>> +interference.
>
> The 3rd approach is only valid if used strictly with device local
> memory, right? Because as soon as system memory backed buffers are
> used this approach cannot guarantee no eviction can be triggered.
>
>> +
>> +The interface to the cgroup would be similar to the current CPU memory
>> +interface, with similar semantics for min/low/high/max, if eviction can
>> +be made cgroup aware. For now only max is implemented.
>> +
>> +What should be noted is that each memory region (tiled memory for
>> example)
>> +should have its own accounting, using $card key0 = value0 key1 =
>> value1.
>> +
>> +The key is set to the regionid set by the driver, for example "tile0".
>> +For the value of $card, we use drmGetUnique().
>> diff --git a/include/linux/cgroup_drm.h b/include/linux/cgroup_drm.h
>> index 8ef66a47619f..4f17b1c85f47 100644
>> --- a/include/linux/cgroup_drm.h
>> +++ b/include/linux/cgroup_drm.h
>> @@ -6,4 +6,85 @@
>> #ifndef _CGROUP_DRM_H
>> #define _CGROUP_DRM_H
>> +#include <linux/types.h>
>> +
>> +#include <drm/drm_managed.h>
>> +
>> +struct drm_device;
>> +struct drm_file;
>> +
>> +struct drmcgroup_state;
>> +
>> +/*
>> + * Use 8 as max, because of N^2 lookup when setting things, can be
>> bumped if needed
>> + * Identical to TTM_NUM_MEM_TYPES to allow simplifying that code.
>> + */
>> +#define DRMCG_MAX_REGIONS 8
>> +
>> +struct drmcgroup_device {
>> + struct list_head list;
>> + struct list_head pools;
>> +
>> + struct {
>> + u64 size;
>> + const char *name;
>> + } regions[DRMCG_MAX_REGIONS];
>> +
>> + /* Name describing the card, set by drmcg_register_device */
>> + const char *name;
>> +
>> +};
>> +
>> +#if IS_ENABLED(CONFIG_CGROUP_DRM)
>> +int drmcg_register_device(struct drm_device *dev,
>> + struct drmcgroup_device *drm_cg);
>> +void drmcg_unregister_device(struct drmcgroup_device *cgdev);
>> +int drmcg_try_charge(struct drmcgroup_state **drmcg,
>> + struct drmcgroup_device *cgdev,
>> + u32 index, u64 size);
>> +void drmcg_uncharge(struct drmcgroup_state *drmcg,
>> + struct drmcgroup_device *cgdev,
>> + u32 index, u64 size);
>> +#else
>> +static inline int
>> +drmcg_register_device(struct drm_device *dev,
>> + struct drm_cgroup *drm_cg)
>> +{
>> + return 0;
>> +}
>> +
>> +static inline void drmcg_unregister_device(struct drmcgroup_device
>> *cgdev)
>> +{
>> +}
>> +
>> +static inline int drmcg_try_charge(struct drmcgroup_state **drmcg,
>> + struct drmcgroup_device *cgdev,
>> + u32 index, u64 size)
>> +{
>> + *drmcg = NULL;
>> + return 0;
>> +}
>> +
>> +static inline void drmcg_uncharge(struct drmcgroup_state *drmcg,
>> + struct drmcgroup_device *cgdev,
>> + u32 index, u64 size)
>> +{ }
>> +#endif
>> +
>> +static inline void drmmcg_unregister_device(struct drm_device *dev,
>> void *arg)
>> +{
>> + drmcg_unregister_device(arg);
>> +}
>> +
>> +/*
>> + * This needs to be done as inline, because cgroup lives in the core
>> + * kernel and it cannot call drm calls directly
>> + */
>> +static inline int drmmcg_register_device(struct drm_device *dev,
>> + struct drmcgroup_device *cgdev)
>> +{
>> + return drmcg_register_device(dev, cgdev) ?:
>> + drmm_add_action_or_reset(dev, drmmcg_unregister_device, cgdev);
>> +}
>> +
>> #endif /* _CGROUP_DRM_H */
>> diff --git a/kernel/cgroup/drm.c b/kernel/cgroup/drm.c
>> index 02c8eaa633d3..a93d9344fd36 100644
>> --- a/kernel/cgroup/drm.c
>> +++ b/kernel/cgroup/drm.c
>> @@ -1,60 +1,557 @@
>> -/* SPDX-License-Identifier: MIT */
>> +// SPDX-License-Identifier: GPL-2.0
>> /*
>> - * Copyright © 2023 Intel Corporation
>> + * Copyright 2023 Intel
>> + * Partially based on the rdma and misc controllers, which bear the
>> following copyrights:
>> + *
>> + * Copyright 2020 Google LLC
>> + * Copyright (C) 2016 Parav Pandit <pandit.parav at gmail.com>
>> */
>> #include <linux/cgroup.h>
>> #include <linux/cgroup_drm.h>
>> +#include <linux/list.h>
>> +#include <linux/mutex.h>
>> +#include <linux/parser.h>
>> #include <linux/slab.h>
>> -struct drm_cgroup_state {
>
> As a side note, it'd be easier to read the diff if you left the name
> as is, and some other details too, like the static root group (I need
> to remind myself if/why I needed it, but does it harm you?) and my
> missed static keywords and needless static struct initialization. I
> will fix that up in my patch localy. Aynway, that way it would maybe
> be less churn from one patch to the other in the series.
>
>> +#include <drm/drm_device.h>
>> +#include <drm/drm_drv.h>
>> +#include <drm/drm_file.h>
>> +#include <drm/drm_managed.h>
>> +
>> +struct drmcgroup_state {
>> struct cgroup_subsys_state css;
>> +
>> + struct list_head pools;
>> };
>> -struct drm_root_cgroup_state {
>> - struct drm_cgroup_state drmcs;
>> +struct drmcgroup_pool_state {
>> + struct drmcgroup_device *device;
>> + struct drmcgroup_resource {
>> + s64 max, used;
>> + } resources[DRMCG_MAX_REGIONS];
>> +
>> + s64 usage_sum;
>> +
>> + struct list_head cg_node;
>
> cg always makes me think cgroup and not css so it is a bit confusing.
>
> Why are two lists needed?
>
>> + struct list_head dev_node;
>> };
>> -static struct drm_root_cgroup_state root_drmcs;
>> +static DEFINE_MUTEX(drmcg_mutex);
>> +static LIST_HEAD(drmcg_devices);
>> -static inline struct drm_cgroup_state *
>> +static inline struct drmcgroup_state *
>> css_to_drmcs(struct cgroup_subsys_state *css)
>> {
>> - return container_of(css, struct drm_cgroup_state, css);
>> + return container_of(css, struct drmcgroup_state, css);
>> +}
>> +
>> +static inline struct drmcgroup_state *get_current_drmcg(void)
>> +{
>> + return css_to_drmcs(task_get_css(current, drm_cgrp_id));
>> +}
>> +
>> +static struct drmcgroup_state *parent_drmcg(struct drmcgroup_state *cg)
>> +{
>> + return css_to_drmcs(cg->css.parent);
>> +}
>> +
>> +static void free_cg_pool_locked(struct drmcgroup_pool_state *pool)
>> +{
>> + lockdep_assert_held(&drmcg_mutex);
>> +
>> + list_del(&pool->cg_node);
>> + list_del(&pool->dev_node);
>> + kfree(pool);
>> +}
>> +
>> +static void
>> +set_resource_max(struct drmcgroup_pool_state *pool, int i, u64 new_max)
>> +{
>> + pool->resources[i].max = new_max;
>> +}
>> +
>> +static void set_all_resource_max_limit(struct drmcgroup_pool_state
>> *rpool)
>> +{
>> + int i;
>> +
>> + for (i = 0; i < DRMCG_MAX_REGIONS; i++)
>> + set_resource_max(rpool, i, S64_MAX);
>> +}
>> +
>> +static void drmcs_offline(struct cgroup_subsys_state *css)
>> +{
>> + struct drmcgroup_state *drmcs = css_to_drmcs(css);
>> + struct drmcgroup_pool_state *pool, *next;
>> +
>> + mutex_lock(&drmcg_mutex);
>> + list_for_each_entry_safe(pool, next, &drmcs->pools, cg_node) {
>> + if (!pool->usage_sum) {
>> + free_cg_pool_locked(pool);
>> + } else {
>> + /* Reset all regions, last uncharge will remove pool */
>> + set_all_resource_max_limit(pool);
>> + }
>> + }
>> + mutex_unlock(&drmcg_mutex);
>> }
>> static void drmcs_free(struct cgroup_subsys_state *css)
>> {
>> - struct drm_cgroup_state *drmcs = css_to_drmcs(css);
>> + struct drmcgroup_state *drmcs = css_to_drmcs(css);
>> - if (drmcs != &root_drmcs.drmcs)
>> - kfree(drmcs);
>> + kfree(drmcs);
>> }
>> static struct cgroup_subsys_state *
>> drmcs_alloc(struct cgroup_subsys_state *parent_css)
>> {
>> - struct drm_cgroup_state *drmcs;
>> + struct drmcgroup_state *drmcs = kzalloc(sizeof(*drmcs),
>> GFP_KERNEL);
>> + if (!drmcs)
>> + return ERR_PTR(-ENOMEM);
>> +
>> + INIT_LIST_HEAD(&drmcs->pools);
>> + return &drmcs->css;
>> +}
>> +
>> +static struct drmcgroup_pool_state *
>> +find_cg_pool_locked(struct drmcgroup_state *drmcs, struct
>> drmcgroup_device *dev)
>> +{
>> + struct drmcgroup_pool_state *pool;
>> +
>> + list_for_each_entry(pool, &drmcs->pools, cg_node)
>> + if (pool->device == dev)
>> + return pool;
>> +
>> + return NULL;
>> +}
>> +
>> +static struct drmcgroup_pool_state *
>> +get_cg_pool_locked(struct drmcgroup_state *drmcs, struct
>> drmcgroup_device *dev)
>> +{
>> + struct drmcgroup_pool_state *pool;
>> +
>> + pool = find_cg_pool_locked(drmcs, dev);
>> + if (pool)
>> + return pool;
>> +
>> + pool = kzalloc(sizeof(*pool), GFP_KERNEL);
>> + if (!pool)
>> + return ERR_PTR(-ENOMEM);
>> +
>> + pool->device = dev;
>> + set_all_resource_max_limit(pool);
>> - if (!parent_css) {
>> - drmcs = &root_drmcs.drmcs;
>> - } else {
>> - drmcs = kzalloc(sizeof(*drmcs), GFP_KERNEL);
>> - if (!drmcs)
>> - return ERR_PTR(-ENOMEM);
>> + INIT_LIST_HEAD(&pool->cg_node);
>> + INIT_LIST_HEAD(&pool->dev_node);
>> + list_add_tail(&pool->cg_node, &drmcs->pools);
>> + list_add_tail(&pool->dev_node, &dev->pools);
>> + return pool;
>> +}
>> +
>> +void drmcg_unregister_device(struct drmcgroup_device *cgdev)
>> +{
>> + struct drmcgroup_pool_state *pool, *next;
>> +
>> + mutex_lock(&drmcg_mutex);
>> + list_del(&cgdev->list);
>> +
>> + list_for_each_entry_safe(pool, next, &cgdev->pools, dev_node)
>> + free_cg_pool_locked(pool);
>> + mutex_unlock(&drmcg_mutex);
>> + kfree(cgdev->name);
>> +}
>> +
>> +EXPORT_SYMBOL_GPL(drmcg_unregister_device);
>> +
>> +int drmcg_register_device(struct drm_device *dev,
>> + struct drmcgroup_device *cgdev)
>> +{
>> + char *name = kstrdup(dev->unique, GFP_KERNEL);
>> + if (!name)
>> + return -ENOMEM;
>> +
>> + INIT_LIST_HEAD(&cgdev->pools);
>> + mutex_lock(&drmcg_mutex);
>> + cgdev->name = name;
>> + list_add_tail(&cgdev->list, &drmcg_devices);
>> + mutex_unlock(&drmcg_mutex);
>> +
>> + return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(drmcg_register_device);
>> +
>> +static int drmcg_max_show(struct seq_file *sf, void *v)
>> +{
>> + struct drmcgroup_state *drmcs = css_to_drmcs(seq_css(sf));
>> + struct drmcgroup_pool_state *pool;
>> +
>> + mutex_lock(&drmcg_mutex);
>> + list_for_each_entry(pool, &drmcs->pools, cg_node) {
>> + struct drmcgroup_device *dev = pool->device;
>> + int i;
>> +
>> + seq_puts(sf, dev->name);
>> +
>> + for (i = 0; i < DRMCG_MAX_REGIONS; i++) {
>> + if (!dev->regions[i].name)
>> + continue;
>> +
>> + if (pool->resources[i].max < S64_MAX)
>> + seq_printf(sf, " region.%s=%lld", dev->regions[i].name,
>> + pool->resources[i].max);
>> + else
>> + seq_printf(sf, " region.%s=max", dev->regions[i].name);
>> + }
>> +
>> + seq_putc(sf, '\n');
>> }
>> + mutex_unlock(&drmcg_mutex);
>> - return &drmcs->css;
>> + return 0;
>> +}
>> +
>> +static struct drmcgroup_device *drmcg_get_device_locked(const char
>> *name)
>> +{
>> + struct drmcgroup_device *dev;
>> +
>> + lockdep_assert_held(&drmcg_mutex);
>> +
>> + list_for_each_entry(dev, &drmcg_devices, list)
>> + if (!strcmp(name, dev->name))
>> + return dev;
>> +
>> + return NULL;
>> +}
>> +
>> +static void try_to_free_cg_pool_locked(struct drmcgroup_pool_state
>> *pool)
>> +{
>> + struct drmcgroup_device *dev = pool->device;
>> + u32 i;
>> +
>> + /* Memory charged to this pool */
>> + if (pool->usage_sum)
>> + return;
>> +
>> + for (i = 0; i < DRMCG_MAX_REGIONS; i++) {
>> + if (!dev->regions[i].name)
>> + continue;
>> +
>> + /* Is a specific limit set? */
>> + if (pool->resources[i].max < S64_MAX)
>> + return;
>> + }
>> +
>> + /*
>> + * No user of the pool and all entries are set to defaults;
>> + * safe to delete this pool.
>> + */
>> + free_cg_pool_locked(pool);
>> +}
>> +
>> +
>> +static void
>> +uncharge_cg_locked(struct drmcgroup_state *drmcs,
>> + struct drmcgroup_device *cgdev,
>> + u32 index, u64 size)
>> +{
>> + struct drmcgroup_pool_state *pool;
>> +
>> + pool = find_cg_pool_locked(drmcs, cgdev);
>> +
>> + if (unlikely(!pool)) {
>> + pr_warn("Invalid device %p or drm cgroup %p\n", cgdev, drmcs);
>> + return;
>> + }
>> +
>> + pool->resources[index].used -= size;
>> +
>> + /*
>> + * A negative count (or overflow) is invalid,
>> + * it indicates a bug in the rdma controller.
>> + */
>> + WARN_ON_ONCE(pool->resources[index].used < 0);
>> + pool->usage_sum--;
>> + try_to_free_cg_pool_locked(pool);
>> +}
>> +
>> +static void drmcg_uncharge_hierarchy(struct drmcgroup_state *drmcs,
>> + struct drmcgroup_device *cgdev,
>> + struct drmcgroup_state *stop_cg,
>> + u32 index, u64 size)
>> +{
>> + struct drmcgroup_state *p;
>> +
>> + mutex_lock(&drmcg_mutex);
>> +
>> + for (p = drmcs; p != stop_cg; p = parent_drmcg(p))
>> + uncharge_cg_locked(p, cgdev, index, size);
>> +
>> + mutex_unlock(&drmcg_mutex);
>> +
>> + css_put(&drmcs->css);
>> +}
>> +
>> +void drmcg_uncharge(struct drmcgroup_state *drmcs,
>> + struct drmcgroup_device *cgdev,
>> + u32 index,
>> + u64 size)
>> +{
>> + if (index >= DRMCG_MAX_REGIONS)
>> + return;
>> +
>> + drmcg_uncharge_hierarchy(drmcs, cgdev, NULL, index, size);
>> +}
>> +EXPORT_SYMBOL_GPL(drmcg_uncharge);
>> +
>> +int drmcg_try_charge(struct drmcgroup_state **drmcs,
>> + struct drmcgroup_device *cgdev,
>> + u32 index,
>> + u64 size)
>> +{
>> + struct drmcgroup_state *cg, *p;
>> + struct drmcgroup_pool_state *pool;
>> + u64 new;
>> + int ret = 0;
>> +
>> + if (index >= DRMCG_MAX_REGIONS)
>> + return -EINVAL;
>> +
>> + /*
>> + * hold on to css, as cgroup can be removed but resource
>> + * accounting happens on css.
>> + */
>> + cg = get_current_drmcg();
>
> 1)
>
> I am not familiar with the Xe flows - charging is at the point of
> actual backing store allocation?
>
> What about buffer sharing?
>
> Also, given how the css is permanently stored in the caller - you
> deliberately decided not to deal with task migrations? I am not sure
> that will work. Or maybe just omitted for RFC v1?
>
> 2)
>
> Buffer objects which Xe can migrate between memory regions will be
> correctly charge/uncharged as they are moved?
>
> Regards,
>
> Tvrtko
>
>> +
>> + mutex_lock(&drmcg_mutex);
>> + for (p = cg; p; p = parent_drmcg(p)) {
>> + pool = get_cg_pool_locked(p, cgdev);
>> + if (IS_ERR(pool)) {
>> + ret = PTR_ERR(pool);
>> + goto err;
>> + } else {
>> + new = pool->resources[index].used + size;
>> + if (new > pool->resources[index].max || new > S64_MAX) {
>> + ret = -EAGAIN;
>> + goto err;
>> + } else {
>> + pool->resources[index].used = new;
>> + pool->usage_sum++;
>> + }
>> + }
>> + }
>> + mutex_unlock(&drmcg_mutex);
>> +
>> + *drmcs = cg;
>> + return 0;
>> +
>> +err:
>> + mutex_unlock(&drmcg_mutex);
>> + drmcg_uncharge_hierarchy(cg, cgdev, p, index, size);
>> + return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(drmcg_try_charge);
>> +
>> +static s64 parse_resource(char *c, char **retname)
>> +{
>> + substring_t argstr;
>> + char *name, *value = c;
>> + size_t len;
>> + int ret;
>> + u64 retval;
>> +
>> + name = strsep(&value, "=");
>> + if (!name || !value)
>> + return -EINVAL;
>> +
>> + /* Only support region setting for now */
>> + if (strncmp(name, "region.", 7))
>> + return -EINVAL;
>> + else
>> + name += 7;
>> +
>> + *retname = name;
>> + len = strlen(value);
>> +
>> + argstr.from = value;
>> + argstr.to = value + len;
>> +
>> + ret = match_u64(&argstr, &retval);
>> + if (ret >= 0) {
>> + if (retval > S64_MAX)
>> + return -EINVAL;
>> + return retval;
>> + }
>> + if (!strncmp(value, "max", len))
>> + return S64_MAX;
>> +
>> + /* Not u64 or max, error */
>> + return -EINVAL;
>> +}
>> +
>> +static int drmcg_parse_limits(char *options,
>> + u64 *limits, char **enables)
>> +{
>> + char *c;
>> + int num_limits = 0;
>> +
>> + /* parse resource options */
>> + while ((c = strsep(&options, " ")) != NULL) {
>> + s64 limit;
>> +
>> + if (num_limits >= DRMCG_MAX_REGIONS)
>> + return -EINVAL;
>> +
>> + limit = parse_resource(c, &enables[num_limits]);
>> + if (limit < 0)
>> + return limit;
>> +
>> + limits[num_limits++] = limit;
>> + }
>> + return num_limits;
>> +}
>> +
>> +static ssize_t drmcg_max_write(struct kernfs_open_file *of,
>> + char *buf, size_t nbytes, loff_t off)
>> +{
>> + struct drmcgroup_state *drmcs = css_to_drmcs(of_css(of));
>> + struct drmcgroup_device *dev;
>> + struct drmcgroup_pool_state *pool;
>> + char *options = strstrip(buf);
>> + char *dev_name = strsep(&options, " ");
>> + u64 limits[DRMCG_MAX_REGIONS];
>> + u64 new_limits[DRMCG_MAX_REGIONS];
>> + char *regions[DRMCG_MAX_REGIONS];
>> + int num_limits, i;
>> + unsigned long set_mask = 0;
>> + int err = 0;
>> +
>> + if (!dev_name)
>> + return -EINVAL;
>> +
>> + num_limits = drmcg_parse_limits(options, limits, regions);
>> + if (num_limits < 0)
>> + return num_limits;
>> + if (!num_limits)
>> + return -EINVAL;
>> +
>> + /*
>> + * Everything is parsed into key=value pairs now, take lock and
>> attempt to update
>> + * For good measure, set -EINVAL when a key is set twice.
>> + */
>> + mutex_lock(&drmcg_mutex);
>> +
>> + dev = drmcg_get_device_locked(dev_name);
>> + if (!dev) {
>> + err = -ENODEV;
>> + goto err;
>> + }
>> +
>> + pool = get_cg_pool_locked(drmcs, dev);
>> + if (IS_ERR(pool)) {
>> + err = PTR_ERR(pool);
>> + goto err;
>> + }
>> +
>> + /* Lookup region names and set new_limits to the index */
>> + for (i = 0; i < num_limits; i++) {
>> + int j;
>> +
>> + for (j = 0; j < DRMCG_MAX_REGIONS; j++)
>> + if (dev->regions[j].name &&
>> + !strcmp(regions[i], dev->regions[j].name))
>> + break;
>> +
>> + if (j == DRMCG_MAX_REGIONS ||
>> + set_mask & BIT(j)) {
>> + err = -EINVAL;
>> + goto err_put;
>> + }
>> +
>> + set_mask |= BIT(j);
>> + new_limits[j] = limits[i];
>> + }
>> +
>> + /* And commit */
>> + for_each_set_bit(i, &set_mask, DRMCG_MAX_REGIONS)
>> + set_resource_max(pool, i, new_limits[i]);
>> +
>> +err_put:
>> + try_to_free_cg_pool_locked(pool);
>> +err:
>> + mutex_unlock(&drmcg_mutex);
>> +
>> + return err ?: nbytes;
>> +}
>> +
>> +static int drmcg_current_show(struct seq_file *sf, void *v)
>> +{
>> + struct drmcgroup_state *drmcs = css_to_drmcs(seq_css(sf));
>> + struct drmcgroup_device *dev;
>> +
>> + mutex_lock(&drmcg_mutex);
>> + list_for_each_entry(dev, &drmcg_devices, list) {
>> + struct drmcgroup_pool_state *pool =
>> find_cg_pool_locked(drmcs, dev);
>> + int i;
>> +
>> + seq_puts(sf, dev->name);
>> +
>> + for (i = 0; i < DRMCG_MAX_REGIONS; i++) {
>> + if (!dev->regions[i].name)
>> + continue;
>> +
>> + seq_printf(sf, " region.%s=%lld", dev->regions[i].name,
>> + pool ? pool->resources[i].used : 0ULL);
>> + }
>> +
>> + seq_putc(sf, '\n');
>> + }
>> + mutex_unlock(&drmcg_mutex);
>> +
>> + return 0;
>> +}
>> +
>> +static int drmcg_capacity_show(struct seq_file *sf, void *v)
>> +{
>> + struct drmcgroup_device *dev;
>> + int i;
>> +
>> + list_for_each_entry(dev, &drmcg_devices, list) {
>> + seq_puts(sf, dev->name);
>> + for (i = 0; i < DRMCG_MAX_REGIONS; i++)
>> + if (dev->regions[i].name)
>> + seq_printf(sf, " region.%s=%lld",
>> + dev->regions[i].name,
>> + dev->regions[i].size);
>> + seq_putc(sf, '\n');
>> + }
>> + return 0;
>> }
>> -struct cftype files[] = {
>> +static struct cftype files[] = {
>> + {
>> + .name = "max",
>> + .write = drmcg_max_write,
>> + .seq_show = drmcg_max_show,
>> + .flags = CFTYPE_NOT_ON_ROOT,
>> + },
>> + {
>> + .name = "current",
>> + .seq_show = drmcg_current_show,
>> + .flags = CFTYPE_NOT_ON_ROOT,
>> + },
>> + {
>> + .name = "capacity",
>> + .seq_show = drmcg_capacity_show,
>> + .flags = CFTYPE_ONLY_ON_ROOT,
>> + },
>> { } /* Zero entry terminates. */
>> };
>> struct cgroup_subsys drm_cgrp_subsys = {
>> .css_alloc = drmcs_alloc,
>> .css_free = drmcs_free,
>> - .early_init = false,
>> + .css_offline = drmcs_offline,
>> .legacy_cftypes = files,
>> .dfl_cftypes = files,
>> };
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