Commit e713d0da authored by Sukadev Bhattiprolu's avatar Sukadev Bhattiprolu Committed by Linus Torvalds
Browse files

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: default avatarSukadev 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4ac24b3b

fs/exec.c

+1 −1
Original line number Diff line number Diff line
@@ -702,7 +702,7 @@ static int de_thread(struct task_struct *tsk) 
		 */

		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);

include/linux/pid.h

+1 −2
Original line number Diff line number Diff line
@@ -76,8 +76,7 @@ extern struct pid *get_task_pid(struct task_struct *task, enum pid_type type); 
 * 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));

kernel/exit.c

+2 −2
Original line number Diff line number Diff line
@@ -302,12 +302,12 @@ void __set_special_pids(pid_t session, pid_t pgrp) 
	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));

	}

}

kernel/fork.c

+7 −4
Original line number Diff line number Diff line
@@ -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++;

	}

kernel/pid.c

+6 −3
Original line number Diff line number Diff line
@@ -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;

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