[PATCH] copy_process: cleanup bad_fork_cleanup_signal

__exit_signal() does important cleanups atomically under ->siglock.  It is
also called from copy_process's error path.  This is not good, for example we
can't move __unhash_process() under ->siglock for that reason.

We should not mix these 2 paths, just look at ugly 'if (p->sighand)' under
'bad_fork_cleanup_sighand:' label.  For copy_process() case it is sufficient
to just backout copy_signal(), nothing more.

Again, nobody can see this task yet.  For CLONE_THREAD case we just decrement
signal->count, otherwise nobody can see this ->signal and we can free it
lockless.

This patch assumes it is safe to do exit_thread_group_keys() without
tasklist_lock.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 1 insertions, 2 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 69c2a1e1529e..7dd430b697aa 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1149,7 +1149,7 @@ extern void flush_thread(void);
 extern void exit_thread(void);
 
 extern void exit_files(struct task_struct *);
-extern void exit_signal(struct task_struct *);
+extern void __cleanup_signal(struct signal_struct *);
 extern void __exit_signal(struct task_struct *);
 extern void __exit_sighand(struct task_struct *);
 extern void exit_itimers(struct signal_struct *);
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 15e1d9736b1b..3af03b19c983 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -210,7 +210,6 @@ extern kmem_cache_t	*names_cachep;
 extern kmem_cache_t     *files_cachep;
 extern kmem_cache_t     *filp_cachep;
 extern kmem_cache_t     *fs_cachep;
-extern kmem_cache_t     *signal_cachep;
 extern kmem_cache_t     *sighand_cachep;
 extern kmem_cache_t     *bio_cachep;