From abe84903a8efc6b83fa92161429e0e3a28bde15c Mon Sep 17 00:00:00 2001 From: Johan Hedberg Date: Wed, 12 Nov 2014 22:22:21 +0200 Subject: Bluetooth: Use proper nesting annotation for l2cap_chan lock By default lockdep considers all L2CAP channels equal. This would mean that we get warnings if a channel is locked when another one's lock is tried to be acquired in the same thread. This kind of inter-channel locking dependencies exist in the form of parent-child channels as well as any channel wishing to elevate the security by requesting procedures on the SMP channel. To eliminate the chance for these lockdep warnings we introduce a nesting level for each channel and use that when acquiring the channel lock. For now there exists the earlier mentioned three identified categories: SMP, "normal" channels and parent channels (i.e. those in BT_LISTEN state). The nesting level is defined as atomic_t since we need access to it before the lock is actually acquired. Signed-off-by: Johan Hedberg Signed-off-by: Marcel Holtmann --- include/net/bluetooth/l2cap.h | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) (limited to 'include/net/bluetooth') diff --git a/include/net/bluetooth/l2cap.h b/include/net/bluetooth/l2cap.h index ead99f032f7..061e648052c 100644 --- a/include/net/bluetooth/l2cap.h +++ b/include/net/bluetooth/l2cap.h @@ -28,6 +28,7 @@ #define __L2CAP_H #include +#include /* L2CAP defaults */ #define L2CAP_DEFAULT_MTU 672 @@ -481,6 +482,7 @@ struct l2cap_chan { struct hci_conn *hs_hcon; struct hci_chan *hs_hchan; struct kref kref; + atomic_t nesting; __u8 state; @@ -713,6 +715,17 @@ enum { FLAG_HOLD_HCI_CONN, }; +/* Lock nesting levels for L2CAP channels. We need these because lockdep + * otherwise considers all channels equal and will e.g. complain about a + * connection oriented channel triggering SMP procedures or a listening + * channel creating and locking a child channel. + */ +enum { + L2CAP_NESTING_SMP, + L2CAP_NESTING_NORMAL, + L2CAP_NESTING_PARENT, +}; + enum { L2CAP_TX_STATE_XMIT, L2CAP_TX_STATE_WAIT_F, @@ -778,7 +791,7 @@ void l2cap_chan_put(struct l2cap_chan *c); static inline void l2cap_chan_lock(struct l2cap_chan *chan) { - mutex_lock(&chan->lock); + mutex_lock_nested(&chan->lock, atomic_read(&chan->nesting)); } static inline void l2cap_chan_unlock(struct l2cap_chan *chan) -- cgit v1.2.3-70-g09d2