From 102a775e3647628727ae83a9a6abf0564c3ca7cb Mon Sep 17 00:00:00 2001 From: Ben Blum Date: Wed, 23 Sep 2009 15:56:26 -0700 Subject: cgroups: add a read-only "procs" file similar to "tasks" that shows only unique tgids struct cgroup used to have a bunch of fields for keeping track of the pidlist for the tasks file. Those are now separated into a new struct cgroup_pidlist, of which two are had, one for procs and one for tasks. The way the seq_file operations are set up is changed so that just the pidlist struct gets passed around as the private data. Interface example: Suppose a multithreaded process has pid 1000 and other threads with ids 1001, 1002, 1003: $ cat tasks 1000 1001 1002 1003 $ cat cgroup.procs 1000 $ Signed-off-by: Ben Blum Signed-off-by: Paul Menage Acked-by: Li Zefan Cc: Matt Helsley Cc: "Eric W. Biederman" Cc: Oleg Nesterov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/cgroup.h | 22 ++++++++++++++-------- 1 file changed, 14 insertions(+), 8 deletions(-) (limited to 'include') diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index c833d6f2367..2357733a0a8 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -141,6 +141,17 @@ enum { CGRP_WAIT_ON_RMDIR, }; +struct cgroup_pidlist { + /* protects the other fields */ + struct rw_semaphore mutex; + /* array of xids */ + pid_t *list; + /* how many elements the above list has */ + int length; + /* how many files are using the current array */ + int use_count; +}; + struct cgroup { unsigned long flags; /* "unsigned long" so bitops work */ @@ -179,14 +190,9 @@ struct cgroup { */ struct list_head release_list; - /* pids_mutex protects the fields below */ - struct rw_semaphore pids_mutex; - /* Array of process ids in the cgroup */ - pid_t *tasks_pids; - /* How many files are using the current tasks_pids array */ - int pids_use_count; - /* Length of the current tasks_pids array */ - int pids_length; + /* we will have two separate pidlists, one for pids (the tasks file) + * and one for tgids (the procs file). */ + struct cgroup_pidlist tasks, procs; /* For RCU-protected deletion */ struct rcu_head rcu_head; -- cgit v1.2.3