Hi,
On Wed, Jan 2, 2019 at 4:11 PM Matthias Kaehlcke <mka@xxxxxxxxxxxx> wrote:
>
> 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@xxxxxxxxxxxx>
> ---
> 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(-)
This looks nice to me, thanks!
Cc: stable@xxxxxxxxxxxxxxx
Reviewed-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
