This patch opens the multilevel model patches.
The multilevel model idea is basically the same as for the flat one,
but in this case task may have many virtual pids - one id for each
sub-namespace this task is visible in. The struct pid carries the
list of pid_number-s and two hash tables are used to find this number
by numerical id and by struct pid.
The struct pid doesn't need the numerical ids any longer. Instead it
has a single linked list of struct pid_number-s which are hashed
for quick search and have the numerical id.
Signed-off-by: Pavel Emelianov <xemul@xxxxxxxxxx>
---
pid.h | 31 +++++++++++++++++++++++++++++++
1 files changed, 31 insertions(+)
--- ./include/linux/pid.h.multdatast 2007-06-15 15:23:00.000000000 +0400
+++ ./include/linux/pid.h 2007-06-15 15:32:15.000000000 +0400
@@ -50,9 +50,33 @@ enum pid_type
* id must be used.
*/
+/*
+ * multilevel pid namespaces
+ * each task may belong to any number of namespaces and thus struct pid do
+ * not carry the number any longer. instead if this struct pid has a list of
+ * pid_number-s each belonging to one namespace. two hashes are used to find
+ * the number - by the numerical id and by the struct pid this nr belongs to.
+ * this allows for creating namespaces of infinite nesting, but has slight
+ * performance problems.
+ */
+
+struct pid_number
+{
+ int nr;
+ struct pid_namespace *ns;
+ struct pid *pid;
+
+ struct hlist_node pid_chain;
+ struct hlist_node nr_chain;
+ struct pid_number *next;
+};
+
struct pid
{
atomic_t count;
+#ifdef CONFIG_PID_NS_MULTILEVEL
+ struct pid_number *pid_nrs;
+#else
/* Try to keep pid_chain in the same cacheline as nr for find_pid */
int nr;
struct hlist_node pid_chain;
@@ -65,11 +89,18 @@ struct pid
struct pid_namespace *ns;
struct hlist_node vpid_chain;
#endif
+#endif
/* lists of tasks that use this pid */
struct hlist_head tasks[PIDTYPE_MAX];
struct rcu_head rcu;
};
+#ifdef CONFIG_PID_NS_MULTILEVEL
+/* small helper to iterate over the pid's numbers */
+#define for_each_pid_nr(nr, pid) \
+ for (nr = pid->pid_nrs; nr != NULL; nr = nr->next)
+#endif
+
extern struct pid init_struct_pid;
struct pid_link
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