linux-toradex.git/kernel/pid.c, branch tegra-9.12.7

pid: generalize task_active_pid_ns

2009-01-08T16:31:12+00:00

Currently task_active_pid_ns is not safe to call after a task becomes a
zombie and exit_task_namespaces is called, as nsproxy becomes NULL.  By
reading the pid namespace from the pid of the task we can trivially solve
this problem at the cost of one extra memory read in what should be the
same cacheline as we read the namespace from.

When moving things around I have made task_active_pid_ns out of line
because keeping it in pid_namespace.h would require adding includes of
pid.h and sched.h that I don't think we want.

This change does make task_active_pid_ns unsafe to call during
copy_process until we attach a pid on the task_struct which seems to be a
reasonable trade off.

Signed-off-by: Eric W. Biederman 
Signed-off-by: Sukadev Bhattiprolu 
Cc: Oleg Nesterov 
Cc: Roland McGrath 
Cc: Bastian Blank 
Cc: Pavel Emelyanov 
Cc: Nadia Derbey 
Acked-by: Serge Hallyn 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

trivial: fix then -> than typos in comments and documentation

2009-01-06T10:28:06+00:00

- (better, more, bigger ...) then -> (...) than

Signed-off-by: Frederik Schwarzer 
Signed-off-by: Jiri Kosina

pidns: remove now unused find_pid function.

2008-07-25T17:53:45+00:00

This one had the only users so far - the kill_proc, which is removed, so
drop this (invalid in namespaced world) call too.

And of course - erase all references on it from comments.

Signed-off-by: Pavel Emelyanov 
Cc: Oleg Nesterov 
Cc: "Eric W. Biederman" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc: misplaced export of find_get_pid

2008-07-25T17:53:45+00:00

Move EXPORT_SYMBOL right after the func

Signed-off-by: David Sterba 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

rcu: split list.h and move rcu-protected lists into rculist.h

2008-05-19T08:01:37+00:00

Move rcu-protected lists from list.h into a new header file rculist.h.

This is done because list are a very used primitive structure all over the
kernel and it's currently impossible to include other header files in this
list.h without creating some circular dependencies.

For example, list.h implements rcu-protected list and uses rcu_dereference()
without including rcupdate.h.  It actually compiles because users of
rcu_dereference() are macros.  Others RCU functions could be used too but
aren't probably because of this.

Therefore this patch creates rculist.h which includes rcupdates without to
many changes/troubles.

Signed-off-by: Franck Bui-Huu 
Acked-by: Paul E. McKenney 
Acked-by: Josh Triplett 
Signed-off-by: Andrew Morton 
Signed-off-by: Ingo Molnar

pids: introduce change_pid() helper

2008-04-30T15:29:48+00:00

Based on Eric W. Biederman's idea.

Without tasklist_lock held task_session()/task_pgrp() can return NULL if the
caller races with setprgp()/setsid() which does detach_pid() + attach_pid().
This can happen even if task == current.

Intoduce the new helper, change_pid(), which should be used instead.  This way
the caller always sees the special pid != NULL, either old or new.

Also change the prototype of attach_pid(), it always returns 0 and nobody
check the returned value.

Signed-off-by: Oleg Nesterov 
Cc:  "Eric W. Biederman" 
Cc: Pavel Emelyanov 
Cc: Roland McGrath 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

pids: de_thread: don't clear session/pgrp pids for the old leader

2008-04-30T15:29:48+00:00

Based on Eric W. Biederman's idea.

Unless task == current, without tasklist_lock held task_session()/task_pgrp()
can return NULL if the caller races with de_thread() which switches the group
leader.

Change transfer_pid() to not clear old->pids[type].pid for the old leader.
This means that its .pid can point to "nowhere", but this is already true for
sub-threads, and the old leader is not group_leader() any longer.  IOW, with
or without this change we can't trust task's special pids unless it is the
group leader.

With this change the following code

	rcu_read_lock();
	task = find_task_by_xxx();
	do_something(task_pgrp(task), task_session(task));
	rcu_read_unlock();

can't race with exec and hit the NULL pid.

Signed-off-by: Oleg Nesterov 
Cc:  "Eric W. Biederman" 
Cc: Pavel Emelyanov 
Cc: Roland McGrath 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Deprecate find_task_by_pid()

2008-04-30T15:29:48+00:00

There are some places that are known to operate on tasks'
global pids only:

* the rest_init() call (called on boot)
* the kgdb's getthread
* the create_kthread() (since the kthread is run in init ns)

So use the find_task_by_pid_ns(..., &init_pid_ns) there
and schedule the find_task_by_pid for removal.

[sukadev@us.ibm.com: Fix warning in kernel/pid.c]
Signed-off-by: Pavel Emelyanov 
Cc: "Eric W. Biederman" 
Signed-off-by: Sukadev Bhattiprolu 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

free_pidmap: turn it into free_pidmap(struct upid *)

2008-04-30T15:29:48+00:00

The callers of free_pidmap() pass 2 members of "struct upid", we can just
pass "struct upid *" instead.  Shaves off 10 bytes from pid.o.

Also, simplify the alloc_pid's "out_free:" error path a little bit.  This
way it looks more clear which subset of pid->numbers[] we are freeing.

Signed-off-by: Oleg Nesterov 
Cc: Pavel Emelyanov 
Cc: "Eric W. Biederman" 
Cc :Roland McGrath 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kernel: remove fastcall in kernel/*

2008-02-08T17:22:31+00:00

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Harvey Harrison 
Acked-by: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds