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-rw-r--r--include/linux/freezer.h48
-rw-r--r--include/linux/sched.h1
-rw-r--r--kernel/fork.c3
-rw-r--r--kernel/power/process.c29
4 files changed, 59 insertions, 22 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
diff --git a/kernel/fork.c b/kernel/fork.c
index 87069cfc18a..73ad5cda1bc 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -45,6 +45,7 @@
#include <linux/acct.h>
#include <linux/tsacct_kern.h>
#include <linux/cn_proc.h>
+#include <linux/freezer.h>
#include <linux/delayacct.h>
#include <linux/taskstats_kern.h>
#include <linux/random.h>
@@ -1405,7 +1406,9 @@ long do_fork(unsigned long clone_flags,
}
if (clone_flags & CLONE_VFORK) {
+ freezer_do_not_count();
wait_for_completion(&vfork);
+ freezer_count();
if (unlikely (current->ptrace & PT_TRACE_VFORK_DONE)) {
current->ptrace_message = nr;
ptrace_notify ((PTRACE_EVENT_VFORK_DONE << 8) | SIGTRAP);
diff --git a/kernel/power/process.c b/kernel/power/process.c
index 02e490e311e..eefca8581fa 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -120,22 +120,12 @@ static unsigned int try_to_freeze_tasks(int freeze_user_space)
cancel_freezing(p);
continue;
}
- if (is_user_space(p)) {
- if (!freeze_user_space)
- continue;
-
- /* Freeze the task unless there is a vfork
- * completion pending
- */
- if (!p->vfork_done)
- freeze_process(p);
- } else {
- if (freeze_user_space)
- continue;
-
- freeze_process(p);
- }
- todo++;
+ if (is_user_space(p) == !freeze_user_space)
+ continue;
+
+ freeze_process(p);
+ if (!freezer_should_skip(p))
+ todo++;
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
yield(); /* Yield is okay here */
@@ -161,7 +151,8 @@ static unsigned int try_to_freeze_tasks(int freeze_user_space)
continue;
task_lock(p);
- if (freezeable(p) && !frozen(p))
+ if (freezeable(p) && !frozen(p) &&
+ !freezer_should_skip(p))
printk(KERN_ERR " %s\n", p->comm);
cancel_freezing(p);
@@ -210,9 +201,7 @@ static void thaw_tasks(int thaw_user_space)
if (is_user_space(p) == !thaw_user_space)
continue;
- if (!thaw_process(p))
- printk(KERN_WARNING " Strange, %s not stopped\n",
- p->comm );
+ thaw_process(p);
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
}