Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   1) //SPDX-License-Identifier: GPL-2.0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   2) #include <linux/cgroup.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   3) #include <linux/sched.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   4) #include <linux/sched/task.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   5) #include <linux/sched/signal.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   6) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   7) #include "cgroup-internal.h"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   8) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   9) #include <trace/events/cgroup.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  10) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  11) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  12)  * Propagate the cgroup frozen state upwards by the cgroup tree.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  13)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  14) static void cgroup_propagate_frozen(struct cgroup *cgrp, bool frozen)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  15) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  16) 	int desc = 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  17) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  18) 	/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  19) 	 * If the new state is frozen, some freezing ancestor cgroups may change
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  20) 	 * their state too, depending on if all their descendants are frozen.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  21) 	 *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  22) 	 * Otherwise, all ancestor cgroups are forced into the non-frozen state.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  23) 	 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  24) 	while ((cgrp = cgroup_parent(cgrp))) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  25) 		if (frozen) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  26) 			cgrp->freezer.nr_frozen_descendants += desc;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  27) 			if (!test_bit(CGRP_FROZEN, &cgrp->flags) &&
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  28) 			    test_bit(CGRP_FREEZE, &cgrp->flags) &&
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  29) 			    cgrp->freezer.nr_frozen_descendants ==
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  30) 			    cgrp->nr_descendants) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  31) 				set_bit(CGRP_FROZEN, &cgrp->flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  32) 				cgroup_file_notify(&cgrp->events_file);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  33) 				TRACE_CGROUP_PATH(notify_frozen, cgrp, 1);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  34) 				desc++;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  35) 			}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  36) 		} else {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  37) 			cgrp->freezer.nr_frozen_descendants -= desc;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  38) 			if (test_bit(CGRP_FROZEN, &cgrp->flags)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  39) 				clear_bit(CGRP_FROZEN, &cgrp->flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  40) 				cgroup_file_notify(&cgrp->events_file);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  41) 				TRACE_CGROUP_PATH(notify_frozen, cgrp, 0);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  42) 				desc++;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  43) 			}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  44) 		}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  45) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  46) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  47) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  48) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  49)  * Revisit the cgroup frozen state.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  50)  * Checks if the cgroup is really frozen and perform all state transitions.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  51)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  52) void cgroup_update_frozen(struct cgroup *cgrp)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  53) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  54) 	bool frozen;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  55) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  56) 	lockdep_assert_held(&css_set_lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  57) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  58) 	/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  59) 	 * If the cgroup has to be frozen (CGRP_FREEZE bit set),
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  60) 	 * and all tasks are frozen and/or stopped, let's consider
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  61) 	 * the cgroup frozen. Otherwise it's not frozen.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  62) 	 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  63) 	frozen = test_bit(CGRP_FREEZE, &cgrp->flags) &&
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  64) 		cgrp->freezer.nr_frozen_tasks == __cgroup_task_count(cgrp);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  65) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  66) 	if (frozen) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  67) 		/* Already there? */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  68) 		if (test_bit(CGRP_FROZEN, &cgrp->flags))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  69) 			return;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  70) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  71) 		set_bit(CGRP_FROZEN, &cgrp->flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  72) 	} else {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  73) 		/* Already there? */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  74) 		if (!test_bit(CGRP_FROZEN, &cgrp->flags))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  75) 			return;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  76) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  77) 		clear_bit(CGRP_FROZEN, &cgrp->flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  78) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  79) 	cgroup_file_notify(&cgrp->events_file);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  80) 	TRACE_CGROUP_PATH(notify_frozen, cgrp, frozen);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  81) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  82) 	/* Update the state of ancestor cgroups. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  83) 	cgroup_propagate_frozen(cgrp, frozen);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  84) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  85) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  86) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  87)  * Increment cgroup's nr_frozen_tasks.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  88)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  89) static void cgroup_inc_frozen_cnt(struct cgroup *cgrp)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  90) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  91) 	cgrp->freezer.nr_frozen_tasks++;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  92) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  93) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  94) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  95)  * Decrement cgroup's nr_frozen_tasks.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  96)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  97) static void cgroup_dec_frozen_cnt(struct cgroup *cgrp)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  98) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  99) 	cgrp->freezer.nr_frozen_tasks--;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 100) 	WARN_ON_ONCE(cgrp->freezer.nr_frozen_tasks < 0);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 101) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 102) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 103) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 104)  * Enter frozen/stopped state, if not yet there. Update cgroup's counters,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 105)  * and revisit the state of the cgroup, if necessary.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 106)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 107) void cgroup_enter_frozen(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 108) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 109) 	struct cgroup *cgrp;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 110) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 111) 	if (current->frozen)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 112) 		return;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 113) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 114) 	spin_lock_irq(&css_set_lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 115) 	current->frozen = true;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 116) 	cgrp = task_dfl_cgroup(current);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 117) 	cgroup_inc_frozen_cnt(cgrp);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 118) 	cgroup_update_frozen(cgrp);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 119) 	spin_unlock_irq(&css_set_lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 120) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 121) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 122) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 123)  * Conditionally leave frozen/stopped state. Update cgroup's counters,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 124)  * and revisit the state of the cgroup, if necessary.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 125)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 126)  * If always_leave is not set, and the cgroup is freezing,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 127)  * we're racing with the cgroup freezing. In this case, we don't
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 128)  * drop the frozen counter to avoid a transient switch to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 129)  * the unfrozen state.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 130)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 131) void cgroup_leave_frozen(bool always_leave)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 132) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 133) 	struct cgroup *cgrp;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 134) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 135) 	spin_lock_irq(&css_set_lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 136) 	cgrp = task_dfl_cgroup(current);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 137) 	if (always_leave || !test_bit(CGRP_FREEZE, &cgrp->flags)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 138) 		cgroup_dec_frozen_cnt(cgrp);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 139) 		cgroup_update_frozen(cgrp);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 140) 		WARN_ON_ONCE(!current->frozen);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 141) 		current->frozen = false;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 142) 	} else if (!(current->jobctl & JOBCTL_TRAP_FREEZE)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 143) 		spin_lock(&current->sighand->siglock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 144) 		current->jobctl |= JOBCTL_TRAP_FREEZE;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 145) 		set_thread_flag(TIF_SIGPENDING);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 146) 		spin_unlock(&current->sighand->siglock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 147) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 148) 	spin_unlock_irq(&css_set_lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 149) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 150) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 151) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 152)  * Freeze or unfreeze the task by setting or clearing the JOBCTL_TRAP_FREEZE
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 153)  * jobctl bit.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 154)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 155) static void cgroup_freeze_task(struct task_struct *task, bool freeze)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 156) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 157) 	unsigned long flags;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 158) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 159) 	/* If the task is about to die, don't bother with freezing it. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 160) 	if (!lock_task_sighand(task, &flags))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 161) 		return;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 162) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 163) 	if (freeze) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 164) 		task->jobctl |= JOBCTL_TRAP_FREEZE;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 165) 		signal_wake_up(task, false);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 166) 	} else {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 167) 		task->jobctl &= ~JOBCTL_TRAP_FREEZE;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 168) 		wake_up_process(task);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 169) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 170) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 171) 	unlock_task_sighand(task, &flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 172) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 173) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 174) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 175)  * Freeze or unfreeze all tasks in the given cgroup.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 176)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 177) static void cgroup_do_freeze(struct cgroup *cgrp, bool freeze)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 178) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 179) 	struct css_task_iter it;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 180) 	struct task_struct *task;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 181) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 182) 	lockdep_assert_held(&cgroup_mutex);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 183) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 184) 	spin_lock_irq(&css_set_lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 185) 	if (freeze)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 186) 		set_bit(CGRP_FREEZE, &cgrp->flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 187) 	else
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 188) 		clear_bit(CGRP_FREEZE, &cgrp->flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 189) 	spin_unlock_irq(&css_set_lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 190) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 191) 	if (freeze)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 192) 		TRACE_CGROUP_PATH(freeze, cgrp);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 193) 	else
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 194) 		TRACE_CGROUP_PATH(unfreeze, cgrp);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 195) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 196) 	css_task_iter_start(&cgrp->self, 0, &it);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 197) 	while ((task = css_task_iter_next(&it))) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 198) 		/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 199) 		 * Ignore kernel threads here. Freezing cgroups containing
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 200) 		 * kthreads isn't supported.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 201) 		 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 202) 		if (task->flags & PF_KTHREAD)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 203) 			continue;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 204) 		cgroup_freeze_task(task, freeze);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 205) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 206) 	css_task_iter_end(&it);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 207) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 208) 	/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 209) 	 * Cgroup state should be revisited here to cover empty leaf cgroups
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 210) 	 * and cgroups which descendants are already in the desired state.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 211) 	 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 212) 	spin_lock_irq(&css_set_lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 213) 	if (cgrp->nr_descendants == cgrp->freezer.nr_frozen_descendants)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 214) 		cgroup_update_frozen(cgrp);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 215) 	spin_unlock_irq(&css_set_lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 216) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 217) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 218) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 219)  * Adjust the task state (freeze or unfreeze) and revisit the state of
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 220)  * source and destination cgroups.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 221)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 222) void cgroup_freezer_migrate_task(struct task_struct *task,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 223) 				 struct cgroup *src, struct cgroup *dst)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 224) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 225) 	lockdep_assert_held(&css_set_lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 226) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 227) 	/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 228) 	 * Kernel threads are not supposed to be frozen at all.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 229) 	 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 230) 	if (task->flags & PF_KTHREAD)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 231) 		return;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 232) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 233) 	/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 234) 	 * It's not necessary to do changes if both of the src and dst cgroups
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 235) 	 * are not freezing and task is not frozen.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 236) 	 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 237) 	if (!test_bit(CGRP_FREEZE, &src->flags) &&
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 238) 	    !test_bit(CGRP_FREEZE, &dst->flags) &&
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 239) 	    !task->frozen)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 240) 		return;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 241) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 242) 	/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 243) 	 * Adjust counters of freezing and frozen tasks.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 244) 	 * Note, that if the task is frozen, but the destination cgroup is not
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 245) 	 * frozen, we bump both counters to keep them balanced.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 246) 	 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 247) 	if (task->frozen) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 248) 		cgroup_inc_frozen_cnt(dst);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 249) 		cgroup_dec_frozen_cnt(src);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 250) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 251) 	cgroup_update_frozen(dst);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 252) 	cgroup_update_frozen(src);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 253) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 254) 	/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 255) 	 * Force the task to the desired state.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 256) 	 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 257) 	cgroup_freeze_task(task, test_bit(CGRP_FREEZE, &dst->flags));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 258) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 259) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 260) void cgroup_freeze(struct cgroup *cgrp, bool freeze)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 261) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 262) 	struct cgroup_subsys_state *css;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 263) 	struct cgroup *dsct;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 264) 	bool applied = false;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 265) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 266) 	lockdep_assert_held(&cgroup_mutex);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 267) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 268) 	/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 269) 	 * Nothing changed? Just exit.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 270) 	 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 271) 	if (cgrp->freezer.freeze == freeze)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 272) 		return;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 273) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 274) 	cgrp->freezer.freeze = freeze;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 275) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 276) 	/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 277) 	 * Propagate changes downwards the cgroup tree.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 278) 	 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 279) 	css_for_each_descendant_pre(css, &cgrp->self) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 280) 		dsct = css->cgroup;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 281) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 282) 		if (cgroup_is_dead(dsct))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 283) 			continue;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 284) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 285) 		if (freeze) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 286) 			dsct->freezer.e_freeze++;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 287) 			/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 288) 			 * Already frozen because of ancestor's settings?
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 289) 			 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 290) 			if (dsct->freezer.e_freeze > 1)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 291) 				continue;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 292) 		} else {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 293) 			dsct->freezer.e_freeze--;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 294) 			/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 295) 			 * Still frozen because of ancestor's settings?
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 296) 			 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 297) 			if (dsct->freezer.e_freeze > 0)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 298) 				continue;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 299) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 300) 			WARN_ON_ONCE(dsct->freezer.e_freeze < 0);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 301) 		}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 302) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 303) 		/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 304) 		 * Do change actual state: freeze or unfreeze.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 305) 		 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 306) 		cgroup_do_freeze(dsct, freeze);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 307) 		applied = true;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 308) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 309) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 310) 	/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 311) 	 * Even if the actual state hasn't changed, let's notify a user.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 312) 	 * The state can be enforced by an ancestor cgroup: the cgroup
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 313) 	 * can already be in the desired state or it can be locked in the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 314) 	 * opposite state, so that the transition will never happen.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 315) 	 * In both cases it's better to notify a user, that there is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 316) 	 * nothing to wait for.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 317) 	 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 318) 	if (!applied) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 319) 		TRACE_CGROUP_PATH(notify_frozen, cgrp,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 320) 				  test_bit(CGRP_FROZEN, &cgrp->flags));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 321) 		cgroup_file_notify(&cgrp->events_file);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 322) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 323) }