From 04a2e6a5cbf84e85fe86de0a18f6509b147e1d89 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Mon, 12 Feb 2007 00:52:56 -0800 Subject: [PATCH] pid: make session_of_pgrp use struct pid instead of pid_t To properly implement a pid namespace I need to deal exclusively in terms of struct pid, because pid_t values become ambiguous. To this end session_of_pgrp is transformed to take and return a struct pid pointer. To avoid the need to worry about reference counting I now require my caller to hold the appropriate locks. Leaving callers repsonsible for increasing the reference count if they need access to the result outside of the locks. Since session_of_pgrp currently only has one caller and that caller simply uses only test the result for equality with another process group, the locking change means I don't actually have to acquire the tasklist_lock at all. tiocspgrp is also modified to take and release the lock. The logic there is a little more complicated but nothing I won't need when I convert pgrp of a tty to a struct pid pointer. Signed-off-by: Eric W. Biederman Cc: Alan Cox Cc: Oleg Nesterov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/exit.c | 16 +++++++--------- 1 file changed, 7 insertions(+), 9 deletions(-) (limited to 'kernel') diff --git a/kernel/exit.c b/kernel/exit.c index 14f1703..3ac6a7a 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -185,21 +185,19 @@ repeat: * This checks not only the pgrp, but falls back on the pid if no * satisfactory pgrp is found. I dunno - gdb doesn't work correctly * without this... + * + * The caller must hold rcu lock or the tasklist lock. */ -int session_of_pgrp(int pgrp) +struct pid *session_of_pgrp(struct pid *pgrp) { struct task_struct *p; - int sid = 0; - - read_lock(&tasklist_lock); + struct pid *sid = NULL; - p = find_task_by_pid_type(PIDTYPE_PGID, pgrp); + p = pid_task(pgrp, PIDTYPE_PGID); if (p == NULL) - p = find_task_by_pid(pgrp); + p = pid_task(pgrp, PIDTYPE_PID); if (p != NULL) - sid = process_session(p); - - read_unlock(&tasklist_lock); + sid = task_session(p); return sid; } -- cgit v1.1