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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Fri, 28 Jun 2024 12:18:56 +0200
Subject: [PATCH 3/3] net: Move flush list retrieval to where it is used.
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.10/older/patches-6.10.2-rt14.tar.xz
The bpf_net_ctx_get_.*_flush_list() are used at the top of the function.
This means the variable is always assigned even if unused. By moving the
function to where it is used, it is possible to delay the initialisation
until it is unavoidable.
Not sure how much this gains in reality but by looking at bq_enqueue()
(in devmap.c) gcc pushes one register less to the stack. \o/.
Move flush list retrieval to where it is used.
Acked-by: Jesper Dangaard Brouer <hawk@kernel.org>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/r/20240628103020.1766241-4-bigeasy@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
kernel/bpf/cpumap.c | 6 ++++--
kernel/bpf/devmap.c | 3 ++-
net/xdp/xsk.c | 6 ++++--
3 files changed, 10 insertions(+), 5 deletions(-)
--- a/kernel/bpf/cpumap.c
+++ b/kernel/bpf/cpumap.c
@@ -707,7 +707,6 @@ static void bq_flush_to_queue(struct xdp
*/
static void bq_enqueue(struct bpf_cpu_map_entry *rcpu, struct xdp_frame *xdpf)
{
- struct list_head *flush_list = bpf_net_ctx_get_cpu_map_flush_list();
struct xdp_bulk_queue *bq = this_cpu_ptr(rcpu->bulkq);
if (unlikely(bq->count == CPU_MAP_BULK_SIZE))
@@ -724,8 +723,11 @@ static void bq_enqueue(struct bpf_cpu_ma
*/
bq->q[bq->count++] = xdpf;
- if (!bq->flush_node.prev)
+ if (!bq->flush_node.prev) {
+ struct list_head *flush_list = bpf_net_ctx_get_cpu_map_flush_list();
+
list_add(&bq->flush_node, flush_list);
+ }
}
int cpu_map_enqueue(struct bpf_cpu_map_entry *rcpu, struct xdp_frame *xdpf,
--- a/kernel/bpf/devmap.c
+++ b/kernel/bpf/devmap.c
@@ -448,7 +448,6 @@ static void *__dev_map_lookup_elem(struc
static void bq_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
struct net_device *dev_rx, struct bpf_prog *xdp_prog)
{
- struct list_head *flush_list = bpf_net_ctx_get_dev_flush_list();
struct xdp_dev_bulk_queue *bq = this_cpu_ptr(dev->xdp_bulkq);
if (unlikely(bq->count == DEV_MAP_BULK_SIZE))
@@ -462,6 +461,8 @@ static void bq_enqueue(struct net_device
* are only ever modified together.
*/
if (!bq->dev_rx) {
+ struct list_head *flush_list = bpf_net_ctx_get_dev_flush_list();
+
bq->dev_rx = dev_rx;
bq->xdp_prog = xdp_prog;
list_add(&bq->flush_node, flush_list);
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -370,15 +370,17 @@ static int xsk_rcv(struct xdp_sock *xs,
int __xsk_map_redirect(struct xdp_sock *xs, struct xdp_buff *xdp)
{
- struct list_head *flush_list = bpf_net_ctx_get_xskmap_flush_list();
int err;
err = xsk_rcv(xs, xdp);
if (err)
return err;
- if (!xs->flush_node.prev)
+ if (!xs->flush_node.prev) {
+ struct list_head *flush_list = bpf_net_ctx_get_xskmap_flush_list();
+
list_add(&xs->flush_node, flush_list);
+ }
return 0;
}
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