From: Asias He Date: Wed, 3 Apr 2013 06:17:37 +0000 (+0800) Subject: tcm_vhost: Use vq->private_data to indicate if the endpoint is setup X-Git-Tag: v3.9-rc7~13^2~6 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4f7f46d32c9875004fae1d57ae3c02cc2e6cd6a3;p=pandora-kernel.git tcm_vhost: Use vq->private_data to indicate if the endpoint is setup Currently, vs->vs_endpoint is used indicate if the endpoint is setup or not. It is set or cleared in vhost_scsi_set_endpoint() or vhost_scsi_clear_endpoint() under the vs->dev.mutex lock. However, when we check it in vhost_scsi_handle_vq(), we ignored the lock. Instead of using the vs->vs_endpoint and the vs->dev.mutex lock to indicate the status of the endpoint, we use per virtqueue vq->private_data to indicate it. In this way, we can only take the vq->mutex lock which is per queue and make the concurrent multiqueue process having less lock contention. Further, in the read side of vq->private_data, we can even do not take the lock if it is accessed in the vhost worker thread, because it is protected by "vhost rcu". (nab: Do s/VHOST_FEATURES/~VHOST_SCSI_FEATURES) Signed-off-by: Asias He Acked-by: Michael S. Tsirkin Signed-off-by: Nicholas Bellinger --- Reading git-diff-tree failed