diff options
| -rw-r--r-- | net/9p/trans_virtio.c | 23 |
1 files changed, 22 insertions, 1 deletions
diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c index c6e1ae2..e8f046b 100644 --- a/net/9p/trans_virtio.c +++ b/net/9p/trans_virtio.c @@ -43,6 +43,7 @@ #include <net/9p/client.h> #include <net/9p/transport.h> #include <linux/scatterlist.h> +#include <linux/swap.h> #include <linux/virtio.h> #include <linux/virtio_9p.h> #include "trans_common.h" @@ -51,6 +52,8 @@ /* a single mutex to manage channel initialization and attachment */ static DEFINE_MUTEX(virtio_9p_lock); +static DECLARE_WAIT_QUEUE_HEAD(vp_wq); +static atomic_t vp_pinned = ATOMIC_INIT(0); /** * struct virtio_chan - per-instance transport information @@ -78,7 +81,10 @@ struct virtio_chan { struct virtqueue *vq; int ring_bufs_avail; wait_queue_head_t *vc_wq; - + /* This is global limit. Since we don't have a global structure, + * will be placing it in each channel. + */ + int p9_max_pages; /* Scatterlist: can be too big for stack. */ struct scatterlist sg[VIRTQUEUE_NUM]; @@ -159,8 +165,11 @@ static void req_done(struct virtqueue *vq) req = p9_tag_lookup(chan->client, rc->tag); if (req->tc->private) { struct trans_rpage_info *rp = req->tc->private; + int p = rp->rp_nr_pages; /*Release pages */ p9_release_req_pages(rp); + atomic_sub(p, &vp_pinned); + wake_up(&vp_wq); if (rp->rp_alloc) kfree(rp); req->tc->private = NULL; @@ -269,6 +278,14 @@ p9_virtio_request(struct p9_client *client, struct p9_req_t *req) int rpinfo_size = sizeof(struct trans_rpage_info) + sizeof(struct page *) * nr_pages; + if (atomic_read(&vp_pinned) >= chan->p9_max_pages) { + err = wait_event_interruptible(vp_wq, + atomic_read(&vp_pinned) < chan->p9_max_pages); + if (err == -ERESTARTSYS) + return err; + P9_DPRINTK(P9_DEBUG_TRANS, "9p: May gup pages now.\n"); + } + if (rpinfo_size <= (req->tc->capacity - req->tc->size)) { /* We can use sdata */ req->tc->private = req->tc->sdata + req->tc->size; @@ -291,6 +308,8 @@ p9_virtio_request(struct p9_client *client, struct p9_req_t *req) if (rpinfo->rp_alloc) kfree(rpinfo); return err; + } else { + atomic_add(rpinfo->rp_nr_pages, &vp_pinned); } } @@ -452,6 +471,8 @@ static int p9_virtio_probe(struct virtio_device *vdev) } init_waitqueue_head(chan->vc_wq); chan->ring_bufs_avail = 1; + /* Ceiling limit to avoid denial of service attacks */ + chan->p9_max_pages = nr_free_buffer_pages()/4; mutex_lock(&virtio_9p_lock); list_add_tail(&chan->chan_list, &virtio_chan_list); |
