From: Sukadev Bhattiprolu <[EMAIL PROTECTED]>
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 <[EMAIL PROTECTED]>
Cc: Cedric Le Goater <[EMAIL PROTECTED]>
Cc: Dave Hansen <[EMAIL PROTECTED]>
Cc: Serge Hallyn <[EMAIL PROTECTED]>
Cc: <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
---
fs/exec.c | 2 +-
include/linux/pid.h | 3 +--
kernel/exit.c | 4 ++--
kernel/fork.c | 11 +++++++----
kernel/pid.c | 9 ++++++---
kernel/sys.c | 2 +-
6 files changed, 18 insertions(+), 13 deletions(-)
diff -puN fs/exec.c~attach_pid-with-struct-pid-parameter fs/exec.c
--- a/fs/exec.c~attach_pid-with-struct-pid-parameter
+++ a/fs/exec.c
@@ -702,7 +702,7 @@ static int de_thread(struct task_struct
*/
detach_pid(tsk, PIDTYPE_PID);
tsk->pid = leader->pid;
- attach_pid(tsk, PIDTYPE_PID, tsk->pid);
+ attach_pid(tsk, PIDTYPE_PID, find_pid(tsk->pid));
transfer_pid(leader, tsk, PIDTYPE_PGID);
transfer_pid(leader, tsk, PIDTYPE_SID);
list_replace_rcu(&leader->tasks, &tsk->tasks);
diff -puN include/linux/pid.h~attach_pid-with-struct-pid-parameter
include/linux/pid.h
--- a/include/linux/pid.h~attach_pid-with-struct-pid-parameter
+++ a/include/linux/pid.h
@@ -76,8 +76,7 @@ extern struct pid *get_task_pid(struct t
* write-held.
*/
extern int FASTCALL(attach_pid(struct task_struct *task,
- enum pid_type type, int nr));
-
+ enum pid_type type, struct pid *pid));
extern void FASTCALL(detach_pid(struct task_struct *task, enum pid_type));
extern void FASTCALL(transfer_pid(struct task_struct *old,
struct task_struct *new, enum pid_type));
diff -puN kernel/exit.c~attach_pid-with-struct-pid-parameter kernel/exit.c
--- a/kernel/exit.c~attach_pid-with-struct-pid-parameter
+++ a/kernel/exit.c
@@ -302,12 +302,12 @@ void __set_special_pids(pid_t session, p
if (process_session(curr) != session) {
detach_pid(curr, PIDTYPE_SID);
set_signal_session(curr->signal, session);
- attach_pid(curr, PIDTYPE_SID, session);
+ attach_pid(curr, PIDTYPE_SID, find_pid(session));
}
if (process_group(curr) != pgrp) {
detach_pid(curr, PIDTYPE_PGID);
curr->signal->pgrp = pgrp;
- attach_pid(curr, PIDTYPE_PGID, pgrp);
+ attach_pid(curr, PIDTYPE_PGID, find_pid(pgrp));
}
}
diff -puN kernel/fork.c~attach_pid-with-struct-pid-parameter kernel/fork.c
--- a/kernel/fork.c~attach_pid-with-struct-pid-parameter
+++ a/kernel/fork.c
@@ -1249,16 +1249,19 @@ static struct task_struct *copy_process(
__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++;
}
diff -puN kernel/pid.c~attach_pid-with-struct-pid-parameter kernel/pid.c
--- a/kernel/pid.c~attach_pid-with-struct-pid-parameter
+++ a/kernel/pid.c
@@ -247,13 +247,16 @@ 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;
diff -puN kernel/sys.c~attach_pid-with-struct-pid-parameter kernel/sys.c
--- a/kernel/sys.c~attach_pid-with-struct-pid-parameter
+++ a/kernel/sys.c
@@ -1488,7 +1488,7 @@ asmlinkage long sys_setpgid(pid_t pid, p
if (process_group(p) != pgid) {
detach_pid(p, PIDTYPE_PGID);
p->signal->pgrp = pgid;
- attach_pid(p, PIDTYPE_PGID, pgid);
+ attach_pid(p, PIDTYPE_PGID, find_pid(pgid));
}
err = 0;
_
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