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author | 2013-04-28 15:38:52 +0300 | |
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committer | 2013-05-01 10:02:52 +0300 | |
commit | 3dfbff328f0491b7049673cf7fd568d26a14fc4d (patch) | |
tree | b9cfadecbf32092cf04f17946dbc8d11d6a5d9fc /drivers/vhost | |
parent | vhost: move vhost-net zerocopy fields to net.c (diff) | |
download | linux-3dfbff328f0491b7049673cf7fd568d26a14fc4d.tar.gz linux-3dfbff328f0491b7049673cf7fd568d26a14fc4d.tar.bz2 linux-3dfbff328f0491b7049673cf7fd568d26a14fc4d.zip |
tcm_vhost: document inflight ref-counting use
Add more comments so we remember not to break it
next time we change things.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Diffstat (limited to 'drivers/vhost')
-rw-r--r-- | drivers/vhost/tcm_vhost.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/drivers/vhost/tcm_vhost.c b/drivers/vhost/tcm_vhost.c index afb530887936..96d3b47c82cd 100644 --- a/drivers/vhost/tcm_vhost.c +++ b/drivers/vhost/tcm_vhost.c @@ -83,9 +83,16 @@ struct vhost_scsi_inflight { struct vhost_scsi_virtqueue { struct vhost_virtqueue vq; - /* Track inflight reqs, protected by vq->mutex */ + /* + * Reference counting for inflight reqs, used for flush operation. At + * each time, one reference tracks new commands submitted, while we + * wait for another one to reach 0. + */ struct vhost_scsi_inflight inflights[2]; - /* Indicate current inflight in use, protected by vq->mutex */ + /* + * Indicate current inflight in use, protected by vq->mutex. + * Writers must also take dev mutex and flush under it. + */ int inflight_idx; }; @@ -1015,6 +1022,7 @@ static void vhost_scsi_flush_vq(struct vhost_scsi *vs, int index) vhost_poll_flush(&vs->vqs[index].vq.poll); } +/* Callers must hold dev mutex */ static void vhost_scsi_flush(struct vhost_scsi *vs) { struct vhost_scsi_inflight *old_inflight[VHOST_SCSI_MAX_VQ]; |