From 2c4704756cab7cfa031ada4dab361562f0e357c0 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Tue, 26 Sep 2017 13:06:43 -0500 Subject: pids: Move the pgrp and session pid pointers from task_struct to signal_struct To access these fields the code always has to go to group leader so going to signal struct is no loss and is actually a fundamental simplification. This saves a little bit of memory by only allocating the pid pointer array once instead of once for every thread, and even better this removes a few potential races caused by the fact that group_leader can be changed by de_thread, while signal_struct can not. Signed-off-by: "Eric W. Biederman" --- include/linux/pid.h | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) (limited to 'include/linux/pid.h') diff --git a/include/linux/pid.h b/include/linux/pid.h index 7633d55d9a24..3d4c504dcc8c 100644 --- a/include/linux/pid.h +++ b/include/linux/pid.h @@ -67,12 +67,6 @@ struct pid extern struct pid init_struct_pid; -struct pid_link -{ - struct hlist_node node; - struct pid *pid; -}; - static inline struct pid *get_pid(struct pid *pid) { if (pid) @@ -177,7 +171,7 @@ pid_t pid_vnr(struct pid *pid); do { \ if ((pid) != NULL) \ hlist_for_each_entry_rcu((task), \ - &(pid)->tasks[type], pids[type].node) { + &(pid)->tasks[type], pid_links[type]) { /* * Both old and new leaders may be attached to -- cgit v1.2.3 From 6883f81aac6f44e7df70a6af189b3689ff52cbfb Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Sun, 4 Jun 2017 04:32:13 -0500 Subject: pid: Implement PIDTYPE_TGID Everywhere except in the pid array we distinguish between a tasks pid and a tasks tgid (thread group id). Even in the enumeration we want that distinction sometimes so we have added __PIDTYPE_TGID. With leader_pid we almost have an implementation of PIDTYPE_TGID in struct signal_struct. Add PIDTYPE_TGID as a first class member of the pid_type enumeration and into the pids array. Then remove the __PIDTYPE_TGID special case and the leader_pid in signal_struct. The net size increase is just an extra pointer added to struct pid and an extra pair of pointers of an hlist_node added to task_struct. The effect on code maintenance is the removal of a number of special cases today and the potential to remove many more special cases as PIDTYPE_TGID gets used to it's fullest. The long term potential is allowing zombie thread group leaders to exit, which will remove a lot more special cases in the code. Signed-off-by: "Eric W. Biederman" --- include/linux/pid.h | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'include/linux/pid.h') diff --git a/include/linux/pid.h b/include/linux/pid.h index 3d4c504dcc8c..14a9a39da9c7 100644 --- a/include/linux/pid.h +++ b/include/linux/pid.h @@ -7,11 +7,10 @@ enum pid_type { PIDTYPE_PID, + PIDTYPE_TGID, PIDTYPE_PGID, PIDTYPE_SID, PIDTYPE_MAX, - /* only valid to __task_pid_nr_ns() */ - __PIDTYPE_TGID }; /* -- cgit v1.2.3