linux: upgrade to stable kernel 6.15.6

6.15.6 include:

From 06a34f7db773e01efa8a90c5b4d912207a80dd60 Mon Sep 17 00:00:00 2001
From: Daniel Borkmann <daniel@iogearbox.net>
Date: Sun, 17 Nov 2024 22:20:30 +0100
Subject: [PATCH] wireguard: device: support big tcp GSO

Advertise GSO_MAX_SIZE as TSO max size in order support BIG TCP for wireguard.
This helps to improve wireguard performance a bit when enabled as it allows
wireguard to aggregate larger skbs in wg_packet_consume_data_done() via
napi_gro_receive(), but also allows the stack to build larger skbs on xmit
where the driver then segments them before encryption inside wg_xmit().
We've seen a 15% improvement in TCP stream performance.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Link: https://patch.msgid.link/20241117212030.629159-5-Jason@zx2c4.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
 drivers/net/wireguard/device.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/wireguard/device.c b/drivers/net/wireguard/device.c
index a2ba71fbbed46..6cf173a008e78 100644
--- a/drivers/net/wireguard/device.c
+++ b/drivers/net/wireguard/device.c
@@ -302,6 +302,8 @@ static void wg_setup(struct net_device *dev)
 	/* We need to keep the dst around in case of icmp replies. */
 	netif_keep_dst(dev);

+	netif_set_tso_max_size(dev, GSO_MAX_SIZE);
+
 	wg->dev = dev;
 }

Signed-off-by: Vincent Li <vincent.mc.li@gmail.com>

lfs/linux

@@ -24,7 +24,7 @@
 
 include Config
 
-VER         = 6.12.26
+VER         = 6.15.6
 
 THISAPP    = linux-$(VER)
 DL_FILE    = linux-$(VER).tar.xz
@@ -72,7 +72,7 @@ objects = \
 
 $(DL_FILE) = $(URL_IPFIRE)/$(DL_FILE)
 
-$(DL_FILE)_BLAKE2 = 3f4382766952a1aea7d3cd5b733b450147d46d92be8338b017f3b8170bb9b2edb377f00f6a11b9be770ce73085eefbe5af8b5e7b7de1cf241ef1f021a41842f3
+$(DL_FILE)_BLAKE2 = 34301ec451141cab53c6017445fb78c6a681095604387b20060e8b2102d9677cf25a3af9f3db56a0b88772434179f730842bce67b718cd28998e5c56178c748a
 
 install : $(TARGET)