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https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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8e4ec90701
cgroup1 freezer piggybacks on the PM freezer, which inadvertently allowed userspace to produce uninterruptible tasks at will. To avoid the issue, cgroup2 freezer switched to a separate job control based mechanism. While this happened a long time ago, the code and comment haven't been updated making it confusing to people who aren't familiar with the history. Rename cgroup_freezing() to cgroup1_freezing() and update comments on top of freezing() and frozen() to clarify that cgroup2 freezer isn't covered by the PM freezer mechanism. Signed-off-by: Tejun Heo <tj@kernel.org> Suggested-by: Qu Wenruo <wqu@suse.com> Link: https://patch.msgid.link/aPZ3q6Hm865NicBC@slm.duckdns.org Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
97 lines
2.7 KiB
C
97 lines
2.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/* Freezer declarations */
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#ifndef FREEZER_H_INCLUDED
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#define FREEZER_H_INCLUDED
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#include <linux/debug_locks.h>
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#include <linux/sched.h>
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#include <linux/wait.h>
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#include <linux/atomic.h>
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#include <linux/jump_label.h>
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#ifdef CONFIG_FREEZER
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DECLARE_STATIC_KEY_FALSE(freezer_active);
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extern bool pm_freezing; /* PM freezing in effect */
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extern bool pm_nosig_freezing; /* PM nosig freezing in effect */
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/*
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* Timeout for stopping processes
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*/
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extern unsigned int freeze_timeout_msecs;
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/*
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* Check if a process has been frozen for PM or cgroup1 freezer. Note that
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* cgroup2 freezer uses the job control mechanism and does not interact with
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* the PM freezer.
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*/
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extern bool frozen(struct task_struct *p);
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extern bool freezing_slow_path(struct task_struct *p);
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/*
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* Check if there is a request to freeze a task from PM or cgroup1 freezer.
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* Note that cgroup2 freezer uses the job control mechanism and does not
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* interact with the PM freezer.
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*/
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static inline bool freezing(struct task_struct *p)
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{
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if (static_branch_unlikely(&freezer_active))
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return freezing_slow_path(p);
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return false;
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}
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/* Takes and releases task alloc lock using task_lock() */
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extern void __thaw_task(struct task_struct *t);
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extern bool __refrigerator(bool check_kthr_stop);
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extern int freeze_processes(void);
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extern int freeze_kernel_threads(void);
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extern void thaw_processes(void);
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extern void thaw_kernel_threads(void);
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extern void thaw_process(struct task_struct *p);
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static inline bool try_to_freeze(void)
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{
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might_sleep();
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if (likely(!freezing(current)))
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return false;
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if (!(current->flags & PF_NOFREEZE))
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debug_check_no_locks_held();
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return __refrigerator(false);
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}
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extern bool freeze_task(struct task_struct *p);
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extern bool set_freezable(void);
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#ifdef CONFIG_CGROUP_FREEZER
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extern bool cgroup1_freezing(struct task_struct *task);
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#else /* !CONFIG_CGROUP_FREEZER */
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static inline bool cgroup1_freezing(struct task_struct *task)
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{
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return false;
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}
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#endif /* !CONFIG_CGROUP_FREEZER */
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#else /* !CONFIG_FREEZER */
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static inline bool frozen(struct task_struct *p) { return false; }
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static inline bool freezing(struct task_struct *p) { return false; }
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static inline void __thaw_task(struct task_struct *t) {}
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static inline bool __refrigerator(bool check_kthr_stop) { return false; }
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static inline int freeze_processes(void) { return -ENOSYS; }
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static inline int freeze_kernel_threads(void) { return -ENOSYS; }
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static inline void thaw_processes(void) {}
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static inline void thaw_kernel_threads(void) {}
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static inline void thaw_process(struct task_struct *p) {}
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static inline bool try_to_freeze(void) { return false; }
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static inline void set_freezable(void) {}
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#endif /* !CONFIG_FREEZER */
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#endif /* FREEZER_H_INCLUDED */
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