From: Oleg Nesterov All members of the process group have the same sid and it can't be == 0. NOTE: this code (and a similar one in sys_setpgid) was needed because it was possibe to have ->session == 0. It's not possible any longer since [PATCH] pidhash: don't use zero pids Commit: c7c6464117a02b0d54feb4ebeca4db70fa493678 Signed-off-by: Oleg Nesterov Signed-off-by: Andrew Morton --- kernel/exit.c | 19 ++++++++----------- 1 file changed, 8 insertions(+), 11 deletions(-) diff -puN kernel/exit.c~session_of_pgrp-kill-unnecessary-do_each_task_pidpidtype_pgid kernel/exit.c --- a/kernel/exit.c~session_of_pgrp-kill-unnecessary-do_each_task_pidpidtype_pgid +++ a/kernel/exit.c @@ -189,21 +189,18 @@ repeat: int session_of_pgrp(int pgrp) { struct task_struct *p; - int sid = -1; + int sid = 0; read_lock(&tasklist_lock); - do_each_task_pid(pgrp, PIDTYPE_PGID, p) { - if (process_session(p) > 0) { - sid = process_session(p); - goto out; - } - } while_each_task_pid(pgrp, PIDTYPE_PGID, p); - p = find_task_by_pid(pgrp); - if (p) + + p = find_task_by_pid_type(PIDTYPE_PGID, pgrp); + if (p == NULL) + p = find_task_by_pid(pgrp); + if (p != NULL) sid = process_session(p); -out: + read_unlock(&tasklist_lock); - + return sid; } _