coredump masking: add an interface for core dump filter

[karo-tx-linux.git] / include / linux / freezer.h

diff --git a/include/linux/freezer.h b/include/linux/freezer.h
index 393063096134d505cedf33fb216ce943bae23b6e..c8e02de737f6b07a3443d53362aee0d3bc507087 100644 (file)
--- a/include/linux/freezer.h
+++ b/include/linux/freezer.h
@@ -1,5 +1,8 @@
 /* Freezer declarations */
 
+#ifndef FREEZER_H_INCLUDED
+#define FREEZER_H_INCLUDED
+
 #include <linux/sched.h>
 
 #ifdef CONFIG_PM
@@ -16,47 +19,48 @@ static inline int frozen(struct task_struct *p)
  */
 static inline int freezing(struct task_struct *p)
 {
-       return p->flags & PF_FREEZE;
+       return test_tsk_thread_flag(p, TIF_FREEZE);
 }
 
 /*
  * Request that a process be frozen
- * FIXME: SMP problem. We may not modify other process' flags!
  */
-static inline void freeze(struct task_struct *p)
+static inline void set_freeze_flag(struct task_struct *p)
 {
-       p->flags |= PF_FREEZE;
+       set_tsk_thread_flag(p, TIF_FREEZE);
 }
 
 /*
  * Sometimes we may need to cancel the previous 'freeze' request
  */
-static inline void do_not_freeze(struct task_struct *p)
+static inline void clear_freeze_flag(struct task_struct *p)
 {
-       p->flags &= ~PF_FREEZE;
+       clear_tsk_thread_flag(p, TIF_FREEZE);
 }
 
 /*
  * Wake up a frozen process
+ *
+ * task_lock() is taken to prevent the race with refrigerator() which may
+ * occur if the freezing of tasks fails.  Namely, without the lock, if the
+ * freezing of tasks failed, thaw_tasks() might have run before a task in
+ * refrigerator() could call frozen_process(), in which case the task would be
+ * frozen and no one would thaw it.
  */
 static inline int thaw_process(struct task_struct *p)
 {
+       task_lock(p);
        if (frozen(p)) {
                p->flags &= ~PF_FROZEN;
+               task_unlock(p);
                wake_up_process(p);
                return 1;
        }
+       clear_freeze_flag(p);
+       task_unlock(p);
        return 0;
 }
 
-/*
- * freezing is complete, mark process as frozen
- */
-static inline void frozen_process(struct task_struct *p)
-{
-       p->flags = (p->flags & ~PF_FREEZE) | PF_FROZEN;
-}
-
 extern void refrigerator(void);
 extern int freeze_processes(void);
 extern void thaw_processes(void);
@@ -70,14 +74,64 @@ 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);
+}
+
+/*
+ * Tell the freezer that the current task should be frozen by it
+ */
+static inline void set_freezable(void)
+{
+       current->flags &= ~PF_NOFREEZE;
+}
 
 #else
 static inline int frozen(struct task_struct *p) { return 0; }
 static inline int freezing(struct task_struct *p) { return 0; }
-static inline void freeze(struct task_struct *p) { BUG(); }
+static inline void set_freeze_flag(struct task_struct *p) {}
+static inline void clear_freeze_flag(struct task_struct *p) {}
 static inline int thaw_process(struct task_struct *p) { return 1; }
-static inline void frozen_process(struct task_struct *p) { BUG(); }
 
 static inline void refrigerator(void) {}
 static inline int freeze_processes(void) { BUG(); return 0; }
@@ -85,5 +139,10 @@ 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; }
+static inline void set_freezable(void) {}
 #endif
+
+#endif /* FREEZER_H_INCLUDED */