path: root/drivers/net/ethernet/cavium
diff options
authorDean Nelson <dnelson@redhat.com>2019-03-26 11:53:26 -0400
committerDavid S. Miller <davem@davemloft.net>2019-03-27 22:52:28 -0700
commitcd35ef91490ad8049dd180bb060aff7ee192eda9 (patch)
tree4eb5a306e4318ed1b799ab6b2efb642afe346eab /drivers/net/ethernet/cavium
parentthunderx: enable page recycling for non-XDP case (diff)
thunderx: eliminate extra calls to put_page() for pages held for recycling
For the non-XDP case, commit 773225388dae15e72790 ("net: thunderx: Optimize page recycling for XDP") added code to nicvf_free_rbdr() that, when releasing the additional receive buffer page reference held for recycling, repeatedly calls put_page() until the page's _refcount goes to zero. Which results in the page being freed. This is not okay if the page's _refcount was greater than 1 (in the non-XDP case), because nicvf_free_rbdr() should not be subtracting more than what nicvf_alloc_page() had previously added to the page's _refcount, which was only 1 (in the non-XDP case). This can arise if a received packet is still being processed and the receive buffer (i.e., skb->head) has not yet been freed via skb_free_head() when nicvf_free_rbdr() is spinning through the aforementioned put_page() loop. If this should occur, when the received packet finishes processing and skb_free_head() is called, various problems can ensue. Exactly what, depends on whether the page has already been reallocated or not, anything from "BUG: Bad page state ... ", to "Unable to handle kernel NULL pointer dereference ..." or "Unable to handle kernel paging request...". So this patch changes nicvf_free_rbdr() to only call put_page() once for pages held for recycling (in the non-XDP case). Fixes: 773225388dae ("net: thunderx: Optimize page recycling for XDP") Signed-off-by: Dean Nelson <dnelson@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/ethernet/cavium')
1 files changed, 3 insertions, 4 deletions
diff --git a/drivers/net/ethernet/cavium/thunder/nicvf_queues.c b/drivers/net/ethernet/cavium/thunder/nicvf_queues.c
index 55dbf02c42af..e246f9733bb8 100644
--- a/drivers/net/ethernet/cavium/thunder/nicvf_queues.c
+++ b/drivers/net/ethernet/cavium/thunder/nicvf_queues.c
@@ -364,11 +364,10 @@ static void nicvf_free_rbdr(struct nicvf *nic, struct rbdr *rbdr)
while (head < rbdr->pgcnt) {
pgcache = &rbdr->pgcache[head];
if (pgcache->page && page_ref_count(pgcache->page) != 0) {
- if (!rbdr->is_xdp) {
- put_page(pgcache->page);
- continue;
+ if (rbdr->is_xdp) {
+ page_ref_sub(pgcache->page,
+ pgcache->ref_count - 1);
- page_ref_sub(pgcache->page, pgcache->ref_count - 1);