On 3/16/21 2:54 PM, Jakub Kicinski wrote:
On Tue, 16 Mar 2021 11:52:43 -0700 Shannon Nelson wrote:
We were linearizing non-TSO skbs that had too many frags, but
we weren't checking number of frags on TSO skbs. This could
lead to a bad page reference when we received a TSO skb with
more frags than the Tx descriptor could support.
Fixes: 0f3154e6bcb3 ("ionic: Add Tx and Rx handling")
Signed-off-by: Shannon Nelson <snel...@pensando.io>
---
.../net/ethernet/pensando/ionic/ionic_txrx.c | 28 ++++++++++---------
1 file changed, 15 insertions(+), 13 deletions(-)
diff --git a/drivers/net/ethernet/pensando/ionic/ionic_txrx.c
b/drivers/net/ethernet/pensando/ionic/ionic_txrx.c
index 162a1ff1e9d2..462b0d106be4 100644
--- a/drivers/net/ethernet/pensando/ionic/ionic_txrx.c
+++ b/drivers/net/ethernet/pensando/ionic/ionic_txrx.c
@@ -1079,25 +1079,27 @@ static int ionic_tx_descs_needed(struct ionic_queue *q,
struct sk_buff *skb)
{
int sg_elems = q->lif->qtype_info[IONIC_QTYPE_TXQ].max_sg_elems;
struct ionic_tx_stats *stats = q_to_tx_stats(q);
+ int ndescs;
int err;
- /* If TSO, need roundup(skb->len/mss) descs */
+ /* If TSO, need roundup(skb->len/mss) descs
+ * If non-TSO, just need 1 desc and nr_frags sg elems
+ */
if (skb_is_gso(skb))
- return (skb->len / skb_shinfo(skb)->gso_size) + 1;
+ ndescs = (skb->len / skb_shinfo(skb)->gso_size) + 1;
Slightly unrelated but why not gso_segs? len / gso_size + 1 could be
over counting, not to mention that div is expensive.
Good catch - we can probably do that.
Are you segmenting in the driver? Why do you need #segs descriptors?
The device needs each descriptor to be no more than mss length, so there
might be a number of descriptors for a large packet.
+ else
+ ndescs = 1;
- /* If non-TSO, just need 1 desc and nr_frags sg elems */
- if (skb_shinfo(skb)->nr_frags <= sg_elems)
- return 1;
+ /* If too many frags, linearize */
+ if (skb_shinfo(skb)->nr_frags > sg_elems) {
+ err = skb_linearize(skb);
+ if (err)
+ return err;
- /* Too many frags, so linearize */
- err = skb_linearize(skb);
- if (err)
- return err;
-
- stats->linearize++;
+ stats->linearize++;
+ }
- /* Need 1 desc and zero sg elems */
- return 1;
+ return ndescs;
I'd be tempted to push back on the refactoring here, you could've
just replaced return 1;s with return ndescs;s without changing
the indentation.. this will give all backporters a pause. But
not the end of the world, I guess.
I can tweak that a little.
I'll send a v2.
sln
}
static int ionic_maybe_stop_tx(struct ionic_queue *q, int ndescs)
