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Date: Fri, 18 Jan 2019 11:49:07 +0100 From: Marcel Holtmann <marcel@...tmann.org> To: Matthias Kaehlcke <mka@...omium.org> Cc: Johan Hedberg <johan.hedberg@...il.com>, "David S. Miller" <davem@...emloft.net>, Dean Jenkins <Dean_Jenkins@...tor.com>, Bluez mailing list <linux-bluetooth@...r.kernel.org>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, netdev <netdev@...r.kernel.org>, Konstantin Khlebnikov <khlebnikov@...dex-team.ru>, Balakrishna Godavarthi <bgodavar@...eaurora.org>, Douglas Anderson <dianders@...omium.org>, Dmitry Grinberg <dmitrygr@...gle.com> Subject: Re: [PATCH v2] Bluetooth: Fix locking in bt_accept_enqueue() for BH context Hi Matthias, > With commit e16337622016 ("Bluetooth: Handle bt_accept_enqueue() socket > atomically") lock_sock[_nested]() is used to acquire the socket lock > before manipulating the socket. lock_sock[_nested]() may block, which > is problematic since bt_accept_enqueue() can be called in bottom half > context (e.g. from rfcomm_connect_ind()): > > [<ffffff80080d81ec>] __might_sleep+0x4c/0x80 > [<ffffff800876c7b0>] lock_sock_nested+0x24/0x58 > [<ffffff8000d7c27c>] bt_accept_enqueue+0x48/0xd4 [bluetooth] > [<ffffff8000e67d8c>] rfcomm_connect_ind+0x190/0x218 [rfcomm] > > Add a parameter to bt_accept_enqueue() to indicate whether the > function is called from BH context, and acquire the socket lock > with bh_lock_sock_nested() if that's the case. > > Also adapt all callers of bt_accept_enqueue() to pass the new > parameter: > > - l2cap_sock_new_connection_cb() > - uses lock_sock() to lock the parent socket => process context > > - rfcomm_connect_ind() > - acquires the parent socket lock with bh_lock_sock() => BH > context > > - __sco_chan_add() > - called from sco_chan_add(), which is called from sco_connect(). > parent is NULL, hence bt_accept_enqueue() isn't called in this > code path and we can ignore it > - also called from sco_conn_ready(). uses bh_lock_sock() to acquire > the parent lock => BH context > > Fixes: e16337622016 ("Bluetooth: Handle bt_accept_enqueue() socket atomically") > Signed-off-by: Matthias Kaehlcke <mka@...omium.org> > --- > Changes in v2: > - use parameter in bt_accept_enqueue() to decide which lock to > acquire and adapt all callers > - updated commit message > --- > include/net/bluetooth/bluetooth.h | 2 +- > net/bluetooth/af_bluetooth.c | 16 +++++++++++++--- > net/bluetooth/l2cap_sock.c | 2 +- > net/bluetooth/rfcomm/sock.c | 2 +- > net/bluetooth/sco.c | 2 +- > 5 files changed, 17 insertions(+), 7 deletions(-) patch has been applied to bluetooth-next tree. Regards Marcel
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