[openwrt/openwrt] generic: backport ("net: free_netdev: exit earlier if dummy")

[LEDE Commits]

robimarko pushed a commit to openwrt/openwrt.git, branch main:
https://git.openwrt.org/7e972fe242240973536d3db55301f0c33ca2fa6b

commit 7e972fe242240973536d3db55301f0c33ca2fa6b
Author: Robert Marko <robimarko at gmail.com>
AuthorDate: Mon Sep 30 12:13:42 2024 +0200

    generic: backport ("net: free_netdev: exit earlier if dummy")
    
    Currently, when removing ath11k or any other driver that uses dummy netdev
    kernel will crash with:
    [  365.004961] ------------[ cut here ]------------
    [  365.004992] kernel BUG at net/core/dev.c:10979!
    [  365.008642] Internal error: Oops - BUG: 00000000f2000800 [#1] SMP
    [  365.012898] Modules linked in: pppoe ppp_async nft_fib_inet nf_flow_table_inet ath11k_ahb(O) ath11k(O) pppox ppp_generic nft_reject_ipv6 nft_reject_ipv4 nft_reject_inet nft_reject nft_redir nft_quota nft_numgen nft_nat nft_masq nft_log nft_limit nft_hash nft_flow_offload nft_fib_c
    [  365.064794] CPU: 3 PID: 3896 Comm: procd Tainted: G           O       6.6.52 #0
    [  365.087031] Hardware name: QNAP 301w (DT)
    [  365.094058] pstate: 20400005 (nzCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
    [  365.098229] pc : free_netdev+0x164/0x1a0
    [  365.104994] lr : free_netdev+0xec/0x1a0
    [  365.109159] sp : ffffffc081d33b90
    [  365.112718] x29: ffffffc081d33b90 x28: ffffff80039d3c00 x27: ffffff800307f000
    [  365.116199] x26: ffffff800538a000 x25: ffffff8005388000 x24: ffffff800538a4c0
    [  365.123317] x23: 00000000000023a4 x22: ffffff8005388f68 x21: ffffff8004e37050
    [  365.130434] x20: ffffff8004e37000 x19: ffffff8004e36ee8 x18: 0000000000000152
    [  365.137552] x17: 63775f357636712e x16: 3030303030646320 x15: ffffffc081436e20
    [  365.144670] x14: ffffff80033f261c x13: 00000000000000d9 x12: 0000000000000002
    [  365.151789] x11: 0000000000000000 x10: 00000000000008a0 x9 : ffffffc081d33980
    [  365.158906] x8 : ffffff80039d4500 x7 : ffffff803fdda6c0 x6 : 0000000000000007
    [  365.166025] x5 : 0000000000000000 x4 : 00000000000000c1 x3 : 00000000000001f4
    [  365.173143] x2 : ffffff803fdd4b78 x1 : ffffff8004e37050 x0 : 0000000000000005
    [  365.180261] Call trace:
    [  365.187370]  free_netdev+0x164/0x1a0
    [  365.189630]  0xffffffc079b373f0
    [  365.193447]  0xffffffc079b374c0
    [  365.196311]  platform_shutdown+0x24/0x34
    [  365.199438]  device_shutdown+0x160/0x268
    [  365.203605]  kernel_restart+0x40/0xc0
    [  365.207510]  __do_sys_reboot+0x104/0x220
    [  365.211070]  __arm64_sys_reboot+0x24/0x30
    [  365.215063]  invoke_syscall.constprop.0+0x5c/0x108
    [  365.218971]  do_el0_svc+0x40/0xc8
    [  365.223655]  el0_svc+0x30/0xb8
    [  365.227041]  el0t_64_sync_handler+0x120/0x12c
    [  365.229995]  el0t_64_sync+0x178/0x17c
    [  365.234424] Code: f94013f5 a8c37bfd d50323bf d65f03c0 (d4210000)
    [  365.238072] ---[ end trace 0000000000000000 ]---
    
    Wireless backports include alloc_netdev_dummy() backport but they dont have
    the required free_netdev change first, so backport it.
    
    Fixes: #16531
    Fixes: 384d079fd876 ("mac80211: update to version 6.11")
    Link: https://github.com/openwrt/openwrt/pull/16549
    Signed-off-by: Robert Marko <robimarko at gmail.com>
---
 ....11-net-free_netdev-exit-earlier-if-dummy.patch | 35 ++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/target/linux/generic/backport-6.6/900-v6.11-net-free_netdev-exit-earlier-if-dummy.patch b/target/linux/generic/backport-6.6/900-v6.11-net-free_netdev-exit-earlier-if-dummy.patch
new file mode 100644
index 0000000000..31beb11d54
--- /dev/null
+++ b/target/linux/generic/backport-6.6/900-v6.11-net-free_netdev-exit-earlier-if-dummy.patch
@@ -0,0 +1,35 @@
+From f8d05679fb3faae478d604177b0c188b340371cd Mon Sep 17 00:00:00 2001
+From: Breno Leitao <leitao at debian.org>
+Date: Mon, 22 Apr 2024 05:38:55 -0700
+Subject: [PATCH] net: free_netdev: exit earlier if dummy
+
+For dummy devices, exit earlier at free_netdev() instead of executing
+the whole function. This is necessary, because dummy devices are
+special, and shouldn't have the second part of the function executed.
+
+Otherwise reg_state, which is NETREG_DUMMY, will be overwritten and
+there will be no way to identify that this is a dummy device. Also, this
+device do not need the final put_device(), since dummy devices are not
+registered (through register_netdevice()), where the device reference is
+increased (at netdev_register_kobject()/device_add()).
+
+Suggested-by: Jakub Kicinski <kuba at kernel.org>
+Signed-off-by: Breno Leitao <leitao at debian.org>
+Reviewed-by: Ido Schimmel <idosch at nvidia.com>
+Signed-off-by: David S. Miller <davem at davemloft.net>
+---
+ net/core/dev.c | 3 ++-
+ 1 file changed, 2 insertions(+), 1 deletion(-)
+
+--- a/net/core/dev.c
++++ b/net/core/dev.c
+@@ -10966,7 +10966,8 @@ void free_netdev(struct net_device *dev)
+ 	dev->xdp_bulkq = NULL;
+ 
+ 	/*  Compatibility with error handling in drivers */
+-	if (dev->reg_state == NETREG_UNINITIALIZED) {
++	if (dev->reg_state == NETREG_UNINITIALIZED ||
++	    dev->reg_state == NETREG_DUMMY) {
+ 		netdev_freemem(dev);
+ 		return;
+ 	}