attach_pid() with struct pid parameter

attach_pid() currently takes a pid_t and then uses find_pid() to find the
corresponding struct pid.  Sometimes we already have the struct pid.  We can
then skip find_pid() if attach_pid() were to take a struct pid parameter.

Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Serge Hallyn <serue@us.ibm.com>
Cc: <containers@lists.osdl.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 4 deletions

diff --git a/kernel/fork.c b/kernel/fork.c
index da92e01aba6b..6031800c94cf 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1249,16 +1249,19 @@ static struct task_struct *copy_process(unsigned long clone_flags,
                         __ptrace_link(p, current->parent);
 
                 if (thread_group_leader(p)) {
+                        pid_t pgid = process_group(current);
+                        pid_t sid = process_session(current);
+
                         p->signal->tty = current->signal->tty;
-                        p->signal->pgrp = process_group(current);
+                        p->signal->pgrp = pgid;
                         set_signal_session(p->signal, process_session(current));
-                        attach_pid(p, PIDTYPE_PGID, process_group(p));
-                        attach_pid(p, PIDTYPE_SID, process_session(p));
+                        attach_pid(p, PIDTYPE_PGID, find_pid(pgid));
+                        attach_pid(p, PIDTYPE_SID, find_pid(sid));
 
                         list_add_tail_rcu(&p->tasks, &init_task.tasks);
                         __get_cpu_var(process_counts)++;
                 }
-                attach_pid(p, PIDTYPE_PID, p->pid);
+                attach_pid(p, PIDTYPE_PID, find_pid(p->pid));
                 nr_threads++;
         }