pi-futex: fix exit races and locking problems

[~andy/linux] / kernel / pid.c

diff --git a/kernel/pid.c b/kernel/pid.c
index d3ad724afa8305548ff5c11b830032366a0592d2..eb66bd2953ab95f614781b12da75b4613ec0f757 100644 (file)
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -27,11 +27,13 @@
 #include <linux/bootmem.h>
 #include <linux/hash.h>
 #include <linux/pid_namespace.h>
+#include <linux/init_task.h>
 
 #define pid_hashfn(nr) hash_long((unsigned long)nr, pidhash_shift)
 static struct hlist_head *pid_hash;
 static int pidhash_shift;
 static struct kmem_cache *pid_cachep;
+struct pid init_struct_pid = INIT_STRUCT_PID;
 
 int pid_max = PID_MAX_DEFAULT;
 
@@ -247,13 +249,16 @@ struct pid * fastcall find_pid(int nr)
 }
 EXPORT_SYMBOL_GPL(find_pid);
 
-int fastcall attach_pid(struct task_struct *task, enum pid_type type, int nr)
+/*
+ * attach_pid() must be called with the tasklist_lock write-held.
+ */
+int fastcall attach_pid(struct task_struct *task, enum pid_type type,
+               struct pid *pid)
 {
        struct pid_link *link;
-       struct pid *pid;
 
        link = &task->pids[type];
-       link->pid = pid = find_pid(nr);
+       link->pid = pid;
        hlist_add_head_rcu(&link->node, &pid->tasks[type]);
 
        return 0;