This is a note to let you know that I've just added the patch titled
net: Fix data-races around netdev_max_backlog.
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
net-fix-data-races-around-netdev_max_backlog.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 1fb30558960b93f0d48e7e43a3cc000139ce2f87
Author: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Date: Tue Aug 23 10:46:46 2022 -0700
net: Fix data-races around netdev_max_backlog.
[ Upstream commit 5dcd08cd19912892586c6082d56718333e2d19db ]
While reading netdev_max_backlog, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its readers.
While at it, we remove the unnecessary spaces in the doc.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/Documentation/admin-guide/sysctl/net.rst b/Documentation/admin-guide/sysctl/net.rst
index 4150f74c521a8..5310f398794c1 100644
--- a/Documentation/admin-guide/sysctl/net.rst
+++ b/Documentation/admin-guide/sysctl/net.rst
@@ -271,7 +271,7 @@ poll cycle or the number of packets processed reaches netdev_budget.
netdev_max_backlog
------------------
-Maximum number of packets, queued on the INPUT side, when the interface
+Maximum number of packets, queued on the INPUT side, when the interface
receives packets faster than kernel can process them.
netdev_rss_key
diff --git a/net/core/dev.c b/net/core/dev.c
index 1a0de071fcf45..87cf2e0d8f6f1 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4589,7 +4589,7 @@ static bool skb_flow_limit(struct sk_buff *skb, unsigned int qlen)
struct softnet_data *sd;
unsigned int old_flow, new_flow;
- if (qlen < (netdev_max_backlog >> 1))
+ if (qlen < (READ_ONCE(netdev_max_backlog) >> 1))
return false;
sd = this_cpu_ptr(&softnet_data);
@@ -4637,7 +4637,7 @@ static int enqueue_to_backlog(struct sk_buff *skb, int cpu,
if (!netif_running(skb->dev))
goto drop;
qlen = skb_queue_len(&sd->input_pkt_queue);
- if (qlen <= netdev_max_backlog && !skb_flow_limit(skb, qlen)) {
+ if (qlen <= READ_ONCE(netdev_max_backlog) && !skb_flow_limit(skb, qlen)) {
if (qlen) {
enqueue:
__skb_queue_tail(&sd->input_pkt_queue, skb);
diff --git a/net/core/gro_cells.c b/net/core/gro_cells.c
index 6eb2e5ec2c506..2f66f3f295630 100644
--- a/net/core/gro_cells.c
+++ b/net/core/gro_cells.c
@@ -26,7 +26,7 @@ int gro_cells_receive(struct gro_cells *gcells, struct sk_buff *skb)
cell = this_cpu_ptr(gcells->cells);
- if (skb_queue_len(&cell->napi_skbs) > netdev_max_backlog) {
+ if (skb_queue_len(&cell->napi_skbs) > READ_ONCE(netdev_max_backlog)) {
drop:
atomic_long_inc(&dev->rx_dropped);
kfree_skb(skb);
diff --git a/net/xfrm/espintcp.c b/net/xfrm/espintcp.c
index 1f08ebf7d80c5..24ca49ecebea3 100644
--- a/net/xfrm/espintcp.c
+++ b/net/xfrm/espintcp.c
@@ -170,7 +170,7 @@ int espintcp_queue_out(struct sock *sk, struct sk_buff *skb)
{
struct espintcp_ctx *ctx = espintcp_getctx(sk);
- if (skb_queue_len(&ctx->out_queue) >= netdev_max_backlog)
+ if (skb_queue_len(&ctx->out_queue) >= READ_ONCE(netdev_max_backlog))
return -ENOBUFS;
__skb_queue_tail(&ctx->out_queue, skb);
diff --git a/net/xfrm/xfrm_input.c b/net/xfrm/xfrm_input.c
index 3df0861d4390f..5f34bc378fdcf 100644
--- a/net/xfrm/xfrm_input.c
+++ b/net/xfrm/xfrm_input.c
@@ -782,7 +782,7 @@ int xfrm_trans_queue_net(struct net *net, struct sk_buff *skb,
trans = this_cpu_ptr(&xfrm_trans_tasklet);
- if (skb_queue_len(&trans->queue) >= netdev_max_backlog)
+ if (skb_queue_len(&trans->queue) >= READ_ONCE(netdev_max_backlog))
return -ENOBUFS;
BUILD_BUG_ON(sizeof(struct xfrm_trans_cb) > sizeof(skb->cb));
