From: Lars Ellenberg Date: Tue, 29 Aug 2017 08:20:44 +0000 (+0200) Subject: drbd: fix race between handshake and admin disconnect/down X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=cde81d99afa4112eecef3f45129b5827f6ac158e;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git drbd: fix race between handshake and admin disconnect/down conn_try_disconnect() could potentialy hit the BUG_ON() in _conn_set_state() where it iterates over _drbd_set_state() and "asserts" via BUG_ON() that the latter was successful. If the STATE_SENT bit was not yet visible to conn_is_valid_transition() early in _conn_request_state(), but became visible before conn_set_state() later in that call path, we could hit the BUG_ON() after _drbd_set_state(), because it returned SS_IN_TRANSIENT_STATE. To avoid that race, we better protect set_bit(SENT_STATE) with the spinlock. Signed-off-by: Philipp Reisner Signed-off-by: Lars Ellenberg Signed-off-by: Jens Axboe --- diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c index 248966727bf6..5e090a1e4f91 100644 --- a/drivers/block/drbd/drbd_receiver.c +++ b/drivers/block/drbd/drbd_receiver.c @@ -1100,7 +1100,10 @@ randomize: idr_for_each_entry(&connection->peer_devices, peer_device, vnr) mutex_lock(peer_device->device->state_mutex); + /* avoid a race with conn_request_state( C_DISCONNECTING ) */ + spin_lock_irq(&connection->resource->req_lock); set_bit(STATE_SENT, &connection->flags); + spin_unlock_irq(&connection->resource->req_lock); idr_for_each_entry(&connection->peer_devices, peer_device, vnr) mutex_unlock(peer_device->device->state_mutex);