[PATCH] pid: add do_each_pid_task

To avoid pid rollover confusion the kernel needs to work with struct pid *
instead of pid_t.  Currently there is not an iterator that walks through all
of the tasks of a given pid type starting with a struct pid.  This prevents us
replacing some pid_t instances with struct pid.  So this patch adds
do_each_pid_task which walks through the set of task for a given pid type
starting with a struct pid.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 13 insertions, 0 deletions

diff --git a/include/linux/pid.h b/include/linux/pid.h
index 359121086de1..8cf9b11ed264 100644
--- a/include/linux/pid.h
+++ b/include/linux/pid.h
@@ -119,4 +119,17 @@ extern void FASTCALL(free_pid(struct pid *pid));
                                 1; }) );                                \
         }
 
+#define do_each_pid_task(pid, type, task)                               \
+        if ((task = pid_task(pid, type))) {                             \
+                prefetch(pid_next(task, type));                         \
+                do {
+
+#define while_each_pid_task(pid, type, task)                            \
+                } while (pid_next(task, type) &&  ({                    \
+                                task = pid_next_task(task, type);       \
+                                rcu_dereference(task);                  \
+                                prefetch(pid_next(task, type));         \
+                                1; }) );                                \
+        }
+
 #endif /* _LINUX_PID_H */