freezer: add missing mb's to freezer_count() and freezer_should_skip() (dd67d32d) · Commits · 戴 / test

include/linux/freezer.h

+42 −8

Original line number	Diff line number	Diff line
		@@ -75,28 +75,62 @@ static inline bool cgroup_freezing(struct task_struct *task)
		*/


		/* Tell the freezer not to count the current task as freezable. */
		/**
		* freezer_do_not_count - tell freezer to ignore %current
		*
		* Tell freezers to ignore the current task when determining whether the
		* target frozen state is reached. IOW, the current task will be
		* considered frozen enough by freezers.
		*
		* The caller shouldn't do anything which isn't allowed for a frozen task
		* until freezer_cont() is called. Usually, freezer[_do_not]_count() pair
		* wrap a scheduling operation and nothing much else.
		*/
		static inline void freezer_do_not_count(void)
		{
		current->flags \|= PF_FREEZER_SKIP;
		}

		/*
		* Tell the freezer to count the current task as freezable again and try to
		* freeze it.
		/**
		* freezer_count - tell freezer to stop ignoring %current
		*
		* Undo freezer_do_not_count(). It tells freezers that %current should be
		* considered again and tries to freeze if freezing condition is already in
		* effect.
		*/
		static inline void freezer_count(void)
		{
		current->flags &= ~PF_FREEZER_SKIP;
		/*
		* If freezing is in progress, the following paired with smp_mb()
		* in freezer_should_skip() ensures that either we see %true
		* freezing() or freezer_should_skip() sees !PF_FREEZER_SKIP.
		*/
		smp_mb();
		try_to_freeze();
		}

		/*
		* Check if the task should be counted as freezable by the freezer
		/**
		* freezer_should_skip - whether to skip a task when determining frozen
		* state is reached
		* @p: task in quesion
		*
		* This function is used by freezers after establishing %true freezing() to
		* test whether a task should be skipped when determining the target frozen
		* state is reached. IOW, if this function returns %true, @p is considered
		* frozen enough.
		*/
		static inline int freezer_should_skip(struct task_struct *p)
		static inline bool freezer_should_skip(struct task_struct *p)
		{
		return !!(p->flags & PF_FREEZER_SKIP);
		/*
		* The following smp_mb() paired with the one in freezer_count()
		* ensures that either freezer_count() sees %true freezing() or we
		* see cleared %PF_FREEZER_SKIP and return %false. This makes it
		* impossible for a task to slip frozen state testing after
		* clearing %PF_FREEZER_SKIP.
		*/
		smp_mb();
		return p->flags & PF_FREEZER_SKIP;
		}

		/*

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