X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=include%2Flinux%2Fpid.h;fp=include%2Flinux%2Fpid.h;h=5e46c1d4e1b479419ba3dfe15aa8b1e9688dbb62;hb=64ba3f394c830ec48a1c31b53dcae312c56f1604;hp=d4a9f83ac3a4a8be16aa59a8b5534e7ee8855840;hpb=be1e6109ac94a859551f8e1774eb9a8469fe055c;p=linux-2.6.git

diff --git a/include/linux/pid.h b/include/linux/pid.h
index d4a9f83ac..5e46c1d4e 100644
--- a/include/linux/pid.h
+++ b/include/linux/pid.h
@@ -1,120 +1,56 @@
 #ifndef _LINUX_PID_H
 #define _LINUX_PID_H
 
-#include <linux/rcupdate.h>
-
 enum pid_type
 {
 	PIDTYPE_PID,
+	PIDTYPE_TGID,
 	PIDTYPE_PGID,
 	PIDTYPE_SID,
 	PIDTYPE_MAX,
 	PIDTYPE_REALPID
 };
 
-/*
- * What is struct pid?
- *
- * A struct pid is the kernel's internal notion of a process identifier.
- * It refers to individual tasks, process groups, and sessions.  While
- * there are processes attached to it the struct pid lives in a hash
- * table, so it and then the processes that it refers to can be found
- * quickly from the numeric pid value.  The attached processes may be
- * quickly accessed by following pointers from struct pid.
- *
- * Storing pid_t values in the kernel and refering to them later has a
- * problem.  The process originally with that pid may have exited and the
- * pid allocator wrapped, and another process could have come along
- * and been assigned that pid.
- *
- * Referring to user space processes by holding a reference to struct
- * task_struct has a problem.  When the user space process exits
- * the now useless task_struct is still kept.  A task_struct plus a
- * stack consumes around 10K of low kernel memory.  More precisely
- * this is THREAD_SIZE + sizeof(struct task_struct).  By comparison
- * a struct pid is about 64 bytes.
- *
- * Holding a reference to struct pid solves both of these problems.
- * It is small so holding a reference does not consume a lot of
- * resources, and since a new struct pid is allocated when the numeric
- * pid value is reused we don't mistakenly refer to new processes.
- */
-
 struct pid
 {
-	atomic_t count;
 	/* Try to keep pid_chain in the same cacheline as nr for find_pid */
 	int nr;
 	struct hlist_node pid_chain;
-	/* lists of tasks that use this pid */
-	struct hlist_head tasks[PIDTYPE_MAX];
-	struct rcu_head rcu;
+	/* list of pids with the same nr, only one of them is in the hash */
+	struct list_head pid_list;
 };
 
-struct pid_link
-{
-	struct hlist_node node;
-	struct pid *pid;
-};
-
-static inline struct pid *get_pid(struct pid *pid)
-{
-	if (pid)
-		atomic_inc(&pid->count);
-	return pid;
-}
-
-extern void FASTCALL(put_pid(struct pid *pid));
-extern struct task_struct *FASTCALL(pid_task(struct pid *pid, enum pid_type));
-extern struct task_struct *FASTCALL(get_pid_task(struct pid *pid,
-						enum pid_type));
+#define pid_task(elem, type) \
+	list_entry(elem, struct task_struct, pids[type].pid_list)
 
 /*
  * attach_pid() and detach_pid() must be called with the tasklist_lock
  * write-held.
  */
-extern int FASTCALL(attach_pid(struct task_struct *task,
-				enum pid_type type, int nr));
+extern int FASTCALL(attach_pid(struct task_struct *task, enum pid_type type, int nr));
 
 extern void FASTCALL(detach_pid(struct task_struct *task, enum pid_type));
 
 /*
  * look up a PID in the hash table. Must be called with the tasklist_lock
- * or rcu_read_lock() held.
- */
-extern struct pid *FASTCALL(find_pid(int nr));
-
-/*
- * Lookup a PID in the hash table, and return with it's count elevated.
+ * held.
  */
-extern struct pid *find_get_pid(int nr);
+extern struct pid *FASTCALL(find_pid(enum pid_type, int));
 
-extern struct pid *alloc_pid(void);
-extern void FASTCALL(free_pid(struct pid *pid));
+extern int alloc_pidmap(void);
+extern void FASTCALL(free_pidmap(int));
+extern void switch_exec_pids(struct task_struct *leader, struct task_struct *thread);
 
-#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));				\
+		prefetch((task)->pids[type].pid_list.next);		\
 		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; }) );				\
-	}
+		} while (task = pid_task((task)->pids[type].pid_list.next,\
+						type),			\
+			prefetch((task)->pids[type].pid_list.next),	\
+			hlist_unhashed(&(task)->pids[type].pid_chain));	\
+	}								\
 
 #endif /* _LINUX_PID_H */