If you lose this race, it can iput a socket inode twice and you get a BUG
in fs/inode.c
When I added the option for user-space to close a socket, I added some
cruft to svc_delete_socket so that I could call that function when closing
a socket per user-space request.
This was the wrong thing to do. I should have just set SK_CLOSE and let
normal mechanisms do the work.
Not only wrong, but buggy. The locking is all wrong and it openned up a
race where-by a socket could be closed twice.
So this patch:
Introduces svc_close_socket which sets SK_CLOSE then either leave
the close up to a thread, or calls svc_delete_socket if it can
get SK_BUSY.
Adds a bias to sk_busy which is removed when SK_DEAD is set,
This avoid races around shutting down the socket.
Changes several 'spin_lock' to 'spin_lock_bh' where the _bh
was missing.
Bugzilla-url: http://bugzilla.kernel.org/show_bug.cgi?id=7916
Signed-off-by: Neil Brown <neilb@suse.de>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
aaf68cfbf2