[PATCH 1/3] uprobes: change uprobe_register() to use uprobe_unregister() instead of __uprobe_unregister()

[Oleg Nesterov]

If register_for_each_vma() fails uprobe_register() can safely drop
uprobe->register_rwsem and use uprobe_unregister(). There is no worry
about the races with another register/unregister, consumer_add() was
already called so this case doesn't differ from _unregister() right
after the successful _register().

Yes this means the extra up_write() + down_write(), but this is the
slow and unlikely case anyway.

Signed-off-by: Oleg Nesterov <o...@redhat.com>
---
 kernel/events/uprobes.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 974474680820..5ea0aabe8774 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1174,16 +1174,18 @@ struct uprobe *uprobe_register(struct inode *inode,
        if (likely(uprobe_is_active(uprobe))) {
                consumer_add(uprobe, uc);
                ret = register_for_each_vma(uprobe, uc);
-               if (ret)
-                       __uprobe_unregister(uprobe, uc);
        }
        up_write(&uprobe->register_rwsem);
        put_uprobe(uprobe);
 
-       if (unlikely(ret == -EAGAIN))
-               goto retry;
+       if (ret) {
+               if (unlikely(ret == -EAGAIN))
+                       goto retry;
+               uprobe_unregister(uprobe, uc);
+               return ERR_PTR(ret);
+       }
 
-       return ret ? ERR_PTR(ret) : uprobe;
+       return uprobe;
 }
 EXPORT_SYMBOL_GPL(uprobe_register);
 
-- 
2.25.1.362.g51ebf55