425 lines
9.8 KiB
C
425 lines
9.8 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/*
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* Miscellaneous cgroup controller
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*
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* Copyright 2020 Google LLC
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* Author: Vipin Sharma <vipinsh@google.com>
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*/
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#include <linux/limits.h>
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#include <linux/cgroup.h>
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#include <linux/errno.h>
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#include <linux/atomic.h>
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#include <linux/slab.h>
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#include <linux/misc_cgroup.h>
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#define MAX_STR "max"
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#define MAX_NUM ULONG_MAX
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/* Miscellaneous res name, keep it in sync with enum misc_res_type */
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static const char *const misc_res_name[] = {
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#ifdef CONFIG_KVM_AMD_SEV
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/* AMD SEV ASIDs resource */
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"sev",
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/* AMD SEV-ES ASIDs resource */
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"sev_es",
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#endif
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};
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/* Root misc cgroup */
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static struct misc_cg root_cg;
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/*
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* Miscellaneous resources capacity for the entire machine. 0 capacity means
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* resource is not initialized or not present in the host.
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*
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* root_cg.max and capacity are independent of each other. root_cg.max can be
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* more than the actual capacity. We are using Limits resource distribution
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* model of cgroup for miscellaneous controller.
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*/
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static unsigned long misc_res_capacity[MISC_CG_RES_TYPES];
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/**
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* parent_misc() - Get the parent of the passed misc cgroup.
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* @cgroup: cgroup whose parent needs to be fetched.
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*
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* Context: Any context.
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* Return:
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* * struct misc_cg* - Parent of the @cgroup.
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* * %NULL - If @cgroup is null or the passed cgroup does not have a parent.
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*/
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static struct misc_cg *parent_misc(struct misc_cg *cgroup)
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{
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return cgroup ? css_misc(cgroup->css.parent) : NULL;
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}
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/**
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* valid_type() - Check if @type is valid or not.
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* @type: misc res type.
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*
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* Context: Any context.
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* Return:
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* * true - If valid type.
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* * false - If not valid type.
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*/
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static inline bool valid_type(enum misc_res_type type)
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{
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return type >= 0 && type < MISC_CG_RES_TYPES;
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}
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/**
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* misc_cg_res_total_usage() - Get the current total usage of the resource.
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* @type: misc res type.
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*
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* Context: Any context.
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* Return: Current total usage of the resource.
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*/
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unsigned long misc_cg_res_total_usage(enum misc_res_type type)
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{
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if (valid_type(type))
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return atomic_long_read(&root_cg.res[type].usage);
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return 0;
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}
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EXPORT_SYMBOL_GPL(misc_cg_res_total_usage);
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/**
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* misc_cg_set_capacity() - Set the capacity of the misc cgroup res.
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* @type: Type of the misc res.
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* @capacity: Supported capacity of the misc res on the host.
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*
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* If capacity is 0 then the charging a misc cgroup fails for that type.
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*
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* Context: Any context.
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* Return:
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* * %0 - Successfully registered the capacity.
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* * %-EINVAL - If @type is invalid.
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*/
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int misc_cg_set_capacity(enum misc_res_type type, unsigned long capacity)
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{
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if (!valid_type(type))
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return -EINVAL;
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WRITE_ONCE(misc_res_capacity[type], capacity);
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return 0;
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}
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EXPORT_SYMBOL_GPL(misc_cg_set_capacity);
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/**
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* misc_cg_cancel_charge() - Cancel the charge from the misc cgroup.
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* @type: Misc res type in misc cg to cancel the charge from.
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* @cg: Misc cgroup to cancel charge from.
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* @amount: Amount to cancel.
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*
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* Context: Any context.
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*/
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static void misc_cg_cancel_charge(enum misc_res_type type, struct misc_cg *cg,
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unsigned long amount)
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{
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WARN_ONCE(atomic_long_add_negative(-amount, &cg->res[type].usage),
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"misc cgroup resource %s became less than 0",
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misc_res_name[type]);
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}
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/**
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* misc_cg_try_charge() - Try charging the misc cgroup.
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* @type: Misc res type to charge.
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* @cg: Misc cgroup which will be charged.
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* @amount: Amount to charge.
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*
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* Charge @amount to the misc cgroup. Caller must use the same cgroup during
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* the uncharge call.
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*
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* Context: Any context.
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* Return:
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* * %0 - If successfully charged.
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* * -EINVAL - If @type is invalid or misc res has 0 capacity.
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* * -EBUSY - If max limit will be crossed or total usage will be more than the
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* capacity.
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*/
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int misc_cg_try_charge(enum misc_res_type type, struct misc_cg *cg,
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unsigned long amount)
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{
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struct misc_cg *i, *j;
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int ret;
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struct misc_res *res;
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int new_usage;
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if (!(valid_type(type) && cg && READ_ONCE(misc_res_capacity[type])))
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return -EINVAL;
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if (!amount)
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return 0;
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for (i = cg; i; i = parent_misc(i)) {
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res = &i->res[type];
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new_usage = atomic_long_add_return(amount, &res->usage);
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if (new_usage > READ_ONCE(res->max) ||
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new_usage > READ_ONCE(misc_res_capacity[type])) {
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ret = -EBUSY;
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goto err_charge;
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}
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}
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return 0;
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err_charge:
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for (j = i; j; j = parent_misc(j)) {
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atomic_long_inc(&j->res[type].events);
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cgroup_file_notify(&j->events_file);
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}
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for (j = cg; j != i; j = parent_misc(j))
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misc_cg_cancel_charge(type, j, amount);
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misc_cg_cancel_charge(type, i, amount);
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return ret;
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}
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EXPORT_SYMBOL_GPL(misc_cg_try_charge);
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/**
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* misc_cg_uncharge() - Uncharge the misc cgroup.
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* @type: Misc res type which was charged.
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* @cg: Misc cgroup which will be uncharged.
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* @amount: Charged amount.
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*
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* Context: Any context.
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*/
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void misc_cg_uncharge(enum misc_res_type type, struct misc_cg *cg,
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unsigned long amount)
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{
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struct misc_cg *i;
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if (!(amount && valid_type(type) && cg))
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return;
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for (i = cg; i; i = parent_misc(i))
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misc_cg_cancel_charge(type, i, amount);
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}
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EXPORT_SYMBOL_GPL(misc_cg_uncharge);
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/**
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* misc_cg_max_show() - Show the misc cgroup max limit.
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* @sf: Interface file
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* @v: Arguments passed
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*
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* Context: Any context.
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* Return: 0 to denote successful print.
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*/
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static int misc_cg_max_show(struct seq_file *sf, void *v)
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{
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int i;
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struct misc_cg *cg = css_misc(seq_css(sf));
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unsigned long max;
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for (i = 0; i < MISC_CG_RES_TYPES; i++) {
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if (READ_ONCE(misc_res_capacity[i])) {
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max = READ_ONCE(cg->res[i].max);
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if (max == MAX_NUM)
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seq_printf(sf, "%s max\n", misc_res_name[i]);
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else
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seq_printf(sf, "%s %lu\n", misc_res_name[i],
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max);
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}
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}
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return 0;
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}
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/**
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* misc_cg_max_write() - Update the maximum limit of the cgroup.
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* @of: Handler for the file.
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* @buf: Data from the user. It should be either "max", 0, or a positive
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* integer.
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* @nbytes: Number of bytes of the data.
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* @off: Offset in the file.
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*
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* User can pass data like:
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* echo sev 23 > misc.max, OR
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* echo sev max > misc.max
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*
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* Context: Any context.
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* Return:
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* * >= 0 - Number of bytes processed in the input.
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* * -EINVAL - If buf is not valid.
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* * -ERANGE - If number is bigger than the unsigned long capacity.
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*/
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static ssize_t misc_cg_max_write(struct kernfs_open_file *of, char *buf,
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size_t nbytes, loff_t off)
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{
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struct misc_cg *cg;
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unsigned long max;
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int ret = 0, i;
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enum misc_res_type type = MISC_CG_RES_TYPES;
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char *token;
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buf = strstrip(buf);
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token = strsep(&buf, " ");
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if (!token || !buf)
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return -EINVAL;
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for (i = 0; i < MISC_CG_RES_TYPES; i++) {
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if (!strcmp(misc_res_name[i], token)) {
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type = i;
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break;
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}
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}
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if (type == MISC_CG_RES_TYPES)
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return -EINVAL;
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if (!strcmp(MAX_STR, buf)) {
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max = MAX_NUM;
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} else {
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ret = kstrtoul(buf, 0, &max);
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if (ret)
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return ret;
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}
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cg = css_misc(of_css(of));
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if (READ_ONCE(misc_res_capacity[type]))
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WRITE_ONCE(cg->res[type].max, max);
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else
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ret = -EINVAL;
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return ret ? ret : nbytes;
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}
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/**
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* misc_cg_current_show() - Show the current usage of the misc cgroup.
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* @sf: Interface file
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* @v: Arguments passed
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*
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* Context: Any context.
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* Return: 0 to denote successful print.
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*/
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static int misc_cg_current_show(struct seq_file *sf, void *v)
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{
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int i;
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unsigned long usage;
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struct misc_cg *cg = css_misc(seq_css(sf));
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for (i = 0; i < MISC_CG_RES_TYPES; i++) {
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usage = atomic_long_read(&cg->res[i].usage);
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if (READ_ONCE(misc_res_capacity[i]) || usage)
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seq_printf(sf, "%s %lu\n", misc_res_name[i], usage);
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}
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return 0;
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}
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/**
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* misc_cg_capacity_show() - Show the total capacity of misc res on the host.
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* @sf: Interface file
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* @v: Arguments passed
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*
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* Only present in the root cgroup directory.
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*
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* Context: Any context.
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* Return: 0 to denote successful print.
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*/
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static int misc_cg_capacity_show(struct seq_file *sf, void *v)
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{
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int i;
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unsigned long cap;
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for (i = 0; i < MISC_CG_RES_TYPES; i++) {
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cap = READ_ONCE(misc_res_capacity[i]);
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if (cap)
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seq_printf(sf, "%s %lu\n", misc_res_name[i], cap);
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}
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return 0;
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}
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static int misc_events_show(struct seq_file *sf, void *v)
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{
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struct misc_cg *cg = css_misc(seq_css(sf));
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unsigned long events, i;
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for (i = 0; i < MISC_CG_RES_TYPES; i++) {
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events = atomic_long_read(&cg->res[i].events);
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if (READ_ONCE(misc_res_capacity[i]) || events)
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seq_printf(sf, "%s.max %lu\n", misc_res_name[i], events);
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}
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return 0;
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}
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/* Misc cgroup interface files */
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static struct cftype misc_cg_files[] = {
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{
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.name = "max",
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.write = misc_cg_max_write,
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.seq_show = misc_cg_max_show,
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.flags = CFTYPE_NOT_ON_ROOT,
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},
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{
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.name = "current",
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.seq_show = misc_cg_current_show,
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.flags = CFTYPE_NOT_ON_ROOT,
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},
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{
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.name = "capacity",
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.seq_show = misc_cg_capacity_show,
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.flags = CFTYPE_ONLY_ON_ROOT,
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},
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{
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.name = "events",
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.flags = CFTYPE_NOT_ON_ROOT,
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.file_offset = offsetof(struct misc_cg, events_file),
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.seq_show = misc_events_show,
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},
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{}
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};
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/**
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* misc_cg_alloc() - Allocate misc cgroup.
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* @parent_css: Parent cgroup.
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*
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* Context: Process context.
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* Return:
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* * struct cgroup_subsys_state* - css of the allocated cgroup.
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* * ERR_PTR(-ENOMEM) - No memory available to allocate.
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*/
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static struct cgroup_subsys_state *
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misc_cg_alloc(struct cgroup_subsys_state *parent_css)
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{
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enum misc_res_type i;
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struct misc_cg *cg;
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if (!parent_css) {
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cg = &root_cg;
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} else {
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cg = kzalloc(sizeof(*cg), GFP_KERNEL);
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if (!cg)
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return ERR_PTR(-ENOMEM);
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}
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for (i = 0; i < MISC_CG_RES_TYPES; i++) {
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WRITE_ONCE(cg->res[i].max, MAX_NUM);
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atomic_long_set(&cg->res[i].usage, 0);
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}
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return &cg->css;
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}
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/**
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* misc_cg_free() - Free the misc cgroup.
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* @css: cgroup subsys object.
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*
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* Context: Any context.
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*/
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static void misc_cg_free(struct cgroup_subsys_state *css)
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{
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kfree(css_misc(css));
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}
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/* Cgroup controller callbacks */
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struct cgroup_subsys misc_cgrp_subsys = {
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.css_alloc = misc_cg_alloc,
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.css_free = misc_cg_free,
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.legacy_cftypes = misc_cg_files,
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.dfl_cftypes = misc_cg_files,
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};
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