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>
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@ -702,7 +702,7 @@ static int de_thread(struct task_struct *tsk)
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*/
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detach_pid(tsk, PIDTYPE_PID);
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tsk->pid = leader->pid;
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attach_pid(tsk, PIDTYPE_PID, tsk->pid);
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attach_pid(tsk, PIDTYPE_PID, find_pid(tsk->pid));
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transfer_pid(leader, tsk, PIDTYPE_PGID);
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transfer_pid(leader, tsk, PIDTYPE_SID);
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list_replace_rcu(&leader->tasks, &tsk->tasks);
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@ -76,8 +76,7 @@ extern struct pid *get_task_pid(struct task_struct *task, enum pid_type type);
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* write-held.
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*/
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extern int FASTCALL(attach_pid(struct task_struct *task,
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enum pid_type type, int nr));
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enum pid_type type, struct pid *pid));
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extern void FASTCALL(detach_pid(struct task_struct *task, enum pid_type));
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extern void FASTCALL(transfer_pid(struct task_struct *old,
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struct task_struct *new, enum pid_type));
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@ -302,12 +302,12 @@ void __set_special_pids(pid_t session, pid_t pgrp)
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if (process_session(curr) != session) {
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detach_pid(curr, PIDTYPE_SID);
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set_signal_session(curr->signal, session);
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attach_pid(curr, PIDTYPE_SID, session);
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attach_pid(curr, PIDTYPE_SID, find_pid(session));
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}
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if (process_group(curr) != pgrp) {
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detach_pid(curr, PIDTYPE_PGID);
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curr->signal->pgrp = pgrp;
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attach_pid(curr, PIDTYPE_PGID, pgrp);
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attach_pid(curr, PIDTYPE_PGID, find_pid(pgrp));
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}
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}
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@ -1249,16 +1249,19 @@ static struct task_struct *copy_process(unsigned long clone_flags,
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__ptrace_link(p, current->parent);
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if (thread_group_leader(p)) {
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pid_t pgid = process_group(current);
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pid_t sid = process_session(current);
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p->signal->tty = current->signal->tty;
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p->signal->pgrp = process_group(current);
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p->signal->pgrp = pgid;
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set_signal_session(p->signal, process_session(current));
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attach_pid(p, PIDTYPE_PGID, process_group(p));
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attach_pid(p, PIDTYPE_SID, process_session(p));
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attach_pid(p, PIDTYPE_PGID, find_pid(pgid));
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attach_pid(p, PIDTYPE_SID, find_pid(sid));
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list_add_tail_rcu(&p->tasks, &init_task.tasks);
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__get_cpu_var(process_counts)++;
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}
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attach_pid(p, PIDTYPE_PID, p->pid);
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attach_pid(p, PIDTYPE_PID, find_pid(p->pid));
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nr_threads++;
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}
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@ -247,13 +247,16 @@ struct pid * fastcall find_pid(int nr)
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}
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EXPORT_SYMBOL_GPL(find_pid);
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int fastcall attach_pid(struct task_struct *task, enum pid_type type, int nr)
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/*
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* attach_pid() must be called with the tasklist_lock write-held.
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*/
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int fastcall attach_pid(struct task_struct *task, enum pid_type type,
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struct pid *pid)
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{
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struct pid_link *link;
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struct pid *pid;
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link = &task->pids[type];
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link->pid = pid = find_pid(nr);
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link->pid = pid;
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hlist_add_head_rcu(&link->node, &pid->tasks[type]);
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return 0;
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@ -1488,7 +1488,7 @@ asmlinkage long sys_setpgid(pid_t pid, pid_t pgid)
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if (process_group(p) != pgid) {
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detach_pid(p, PIDTYPE_PGID);
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p->signal->pgrp = pgid;
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attach_pid(p, PIDTYPE_PGID, pgid);
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attach_pid(p, PIDTYPE_PGID, find_pid(pgid));
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}
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err = 0;
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