From 46f382d2b69d2221086b823f0dbc8f32c027cac2 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Fri, 8 Feb 2008 04:19:19 -0800 Subject: [PATCH] uglify while_each_pid_task() to make sure we don't count the execing pricess twice There is a window when de_thread() switches the leader and drops tasklist_lock. In that window do_each_pid_task(PIDTYPE_PID) finds both new and old leaders. The problem is pretty much theoretical and probably can be ignored. Currently the only users of do_each_pid_task(PIDTYPE_PID) are send_sigio/send_sigurg, so they can send the signal to the same process twice. Signed-off-by: Oleg Nesterov Cc: "Eric W. Biederman" Cc: Davide Libenzi Cc: Pavel Emelyanov Cc: Roland McGrath Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/pid.h | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/include/linux/pid.h b/include/linux/pid.h index b91f4732dc1b..f84d532b5d23 100644 --- a/include/linux/pid.h +++ b/include/linux/pid.h @@ -152,7 +152,13 @@ pid_t pid_vnr(struct pid *pid); hlist_for_each_entry_rcu((task), pos___, \ &pid->tasks[type], pids[type].node) { + /* + * Both old and new leaders may be attached to + * the same pid in the middle of de_thread(). + */ #define while_each_pid_task(pid, type, task) \ + if (type == PIDTYPE_PID) \ + break; \ } \ } while (0) -- 2.30.2