[PATCH] pid: simplify pid iterators

I think it is hardly possible to read the current do_each_task_pid().  The
new version is much simpler and makes the code smaller.

Only the do_each_task_pid change is tested, the do_each_pid_task isn't.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "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, 23 insertions, 36 deletions

diff --git a/include/linux/pid.h b/include/linux/pid.h
index dba1b2d677a3..7e39767b4c60 100644
--- a/include/linux/pid.h
+++ b/include/linux/pid.h
@@ -102,42 +102,29 @@ static inline pid_t pid_nr(struct pid *pid)
         return nr;
 }
 
-#define pid_next(task, type)                                    \
-        ((task)->pids[(type)].node.next)
 
-#define pid_next_task(task, type)                               \
-        hlist_entry(pid_next(task, type), struct task_struct,   \
-                        pids[(type)].node)
-
-
-/* We could use hlist_for_each_entry_rcu here but it takes more arguments
- * than the do_each_task_pid/while_each_task_pid.  So we roll our own
- * to preserve the existing interface.
- */
-#define do_each_task_pid(who, type, task)                               \
-        if ((task = find_task_by_pid_type(type, who))) {                \
-                prefetch(pid_next(task, type));                         \
-                do {
-
-#define while_each_task_pid(who, type, task)                            \
-                } while (pid_next(task, type) &&  ({                    \
-                                task = pid_next_task(task, type);       \
-                                rcu_dereference(task);                  \
-                                prefetch(pid_next(task, type));         \
-                                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; }) );                                \
-        }
+#define do_each_task_pid(who, type, task)                                       \
+        do {                                                                    \
+                struct hlist_node *pos___;                                      \
+                struct pid *pid___ = find_pid(who);                             \
+                if (pid___ != NULL)                                             \
+                        hlist_for_each_entry_rcu((task), pos___,                \
+                                &pid___->tasks[type], pids[type].node) {
+
+#define while_each_task_pid(who, type, task)                                    \
+                        }                                                       \
+        } while (0)
+
+
+#define do_each_pid_task(pid, type, task)                                       \
+        do {                                                                    \
+                struct hlist_node *pos___;                                      \
+                if (pid != NULL)                                                \
+                        hlist_for_each_entry_rcu((task), pos___,                \
+                                &pid->tasks[type], pids[type].node) {
+
+#define while_each_pid_task(pid, type, task)                                    \
+                        }                                                       \
+        } while (0)
 
 #endif /* _LINUX_PID_H */