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424 lines
9.8 KiB
424 lines
9.8 KiB
// 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 <[email protected]> |
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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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