From ed5d2cac114202fe2978a9cbcab8f5032796d538 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Mon, 4 Feb 2008 22:27:24 -0800 Subject: exec: rework the group exit and fix the race with kill As Roland pointed out, we have the very old problem with exec. de_thread() sets SIGNAL_GROUP_EXIT, kills other threads, changes ->group_leader and then clears signal->flags. All signals (even fatal ones) sent in this window (which is not too small) will be lost. With this patch exec doesn't abuse SIGNAL_GROUP_EXIT. signal_group_exit(), the new helper, should be used to detect exit_group() or exec() in progress. It can have more users, but this patch does only strictly necessary changes. Signed-off-by: Oleg Nesterov Cc: Davide Libenzi Cc: Ingo Molnar Cc: Robin Holt Cc: Roland McGrath Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/sched.h | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'include/linux') diff --git a/include/linux/sched.h b/include/linux/sched.h index 680bb03a4b9..483ea4e1acc 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -555,6 +555,13 @@ struct signal_struct { #define SIGNAL_STOP_CONTINUED 0x00000004 /* SIGCONT since WCONTINUED reap */ #define SIGNAL_GROUP_EXIT 0x00000008 /* group exit in progress */ +/* If true, all threads except ->group_exit_task have pending SIGKILL */ +static inline int signal_group_exit(const struct signal_struct *sig) +{ + return (sig->flags & SIGNAL_GROUP_EXIT) || + (sig->group_exit_task != NULL); +} + /* * Some day this will be a full-fledged user tracking system.. */ -- cgit v1.2.3