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[PATCH] RCU signal handling

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RCU tasklist_lock and RCU signal handling: send signals RCU-read-locked
instead of tasklist_lock read-locked.  This is a scalability improvement on
SMP and a preemption-latency improvement under PREEMPT_RCU.

Signed-off-by: Paul E. McKenney <paulmck@us.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: William Irwin <wli@holomorphy.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Ingo Molnar 2006-01-08 01:01:37 -08:00 • committed by Linus Torvalds
parent 4369ef3c3e
commit e56d090310
8 changed files with 143 additions and 31 deletions
Download patch file Download diff file Expand all files Collapse all files

22
kernel/pid.c
View file

@ -136,7 +136,7 @@ struct pid * fastcall find_pid(enum pid_type type, int nr)
struct hlist_node *elem;
struct pid *pid;
hlist_for_each_entry(pid, elem,
hlist_for_each_entry_rcu(pid, elem,
&pid_hash[type][pid_hashfn(nr)], pid_chain) {
if (pid->nr == nr)
return pid;
@ -150,15 +150,15 @@ int fastcall attach_pid(task_t *task, enum pid_type type, int nr)
task_pid = &task->pids[type];
pid = find_pid(type, nr);
task_pid->nr = nr;
if (pid == NULL) {
hlist_add_head(&task_pid->pid_chain,
&pid_hash[type][pid_hashfn(nr)]);
INIT_LIST_HEAD(&task_pid->pid_list);
hlist_add_head_rcu(&task_pid->pid_chain,
&pid_hash[type][pid_hashfn(nr)]);
} else {
INIT_HLIST_NODE(&task_pid->pid_chain);
list_add_tail(&task_pid->pid_list, &pid->pid_list);
list_add_tail_rcu(&task_pid->pid_list, &pid->pid_list);
}
task_pid->nr = nr;
return 0;
}
@ -170,20 +170,20 @@ static fastcall int __detach_pid(task_t *task, enum pid_type type)
pid = &task->pids[type];
if (!hlist_unhashed(&pid->pid_chain)) {
hlist_del(&pid->pid_chain);
if (list_empty(&pid->pid_list))
if (list_empty(&pid->pid_list)) {
nr = pid->nr;
else {
hlist_del_rcu(&pid->pid_chain);
} else {
pid_next = list_entry(pid->pid_list.next,
struct pid, pid_list);
/* insert next pid from pid_list to hash */
hlist_add_head(&pid_next->pid_chain,
&pid_hash[type][pid_hashfn(pid_next->nr)]);
hlist_replace_rcu(&pid->pid_chain,
&pid_next->pid_chain);
}
}
list_del(&pid->pid_list);
list_del_rcu(&pid->pid_list);
pid->nr = 0;
return nr;