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-rw-r--r--include/linux/freezer.h48
-rw-r--r--include/linux/sched.h1
2 files changed, 47 insertions, 2 deletions
diff --git a/include/linux/freezer.h b/include/linux/freezer.h
index db5423eae24..c9435252e8e 100644
--- a/include/linux/freezer.h
+++ b/include/linux/freezer.h
@@ -81,7 +81,49 @@ static inline int try_to_freeze(void)
return 0;
}
-extern void thaw_some_processes(int all);
+/*
+ * The PF_FREEZER_SKIP flag should be set by a vfork parent right before it
+ * calls wait_for_completion(&vfork) and reset right after it returns from this
+ * function. Next, the parent should call try_to_freeze() to freeze itself
+ * appropriately in case the child has exited before the freezing of tasks is
+ * complete. However, we don't want kernel threads to be frozen in unexpected
+ * places, so we allow them to block freeze_processes() instead or to set
+ * PF_NOFREEZE if needed and PF_FREEZER_SKIP is only set for userland vfork
+ * parents. Fortunately, in the ____call_usermodehelper() case the parent won't
+ * really block freeze_processes(), since ____call_usermodehelper() (the child)
+ * does a little before exec/exit and it can't be frozen before waking up the
+ * parent.
+ */
+
+/*
+ * If the current task is a user space one, tell the freezer not to count it as
+ * freezable.
+ */
+static inline void freezer_do_not_count(void)
+{
+ if (current->mm)
+ current->flags |= PF_FREEZER_SKIP;
+}
+
+/*
+ * If the current task is a user space one, tell the freezer to count it as
+ * freezable again and try to freeze it.
+ */
+static inline void freezer_count(void)
+{
+ if (current->mm) {
+ current->flags &= ~PF_FREEZER_SKIP;
+ try_to_freeze();
+ }
+}
+
+/*
+ * Check if the task should be counted as freezeable by the freezer
+ */
+static inline int freezer_should_skip(struct task_struct *p)
+{
+ return !!(p->flags & PF_FREEZER_SKIP);
+}
#else
static inline int frozen(struct task_struct *p) { return 0; }
@@ -96,5 +138,7 @@ static inline void thaw_processes(void) {}
static inline int try_to_freeze(void) { return 0; }
-
+static inline void freezer_do_not_count(void) {}
+static inline void freezer_count(void) {}
+static inline int freezer_should_skip(struct task_struct *p) { return 0; }
#endif
diff --git a/include/linux/sched.h b/include/linux/sched.h
index a81897e2a24..870b75e348a 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1182,6 +1182,7 @@ static inline void put_task_struct(struct task_struct *t)
#define PF_SPREAD_SLAB 0x02000000 /* Spread some slab caches over cpuset */
#define PF_MEMPOLICY 0x10000000 /* Non-default NUMA mempolicy */
#define PF_MUTEX_TESTER 0x20000000 /* Thread belongs to the rt mutex tester */
+#define PF_FREEZER_SKIP 0x40000000 /* Freezer should not count it as freezeable */
/*
* Only the _current_ task can read/write to tsk->flags, but other