[PATCH iwl-net v3] ice: Add netif_device_attach/detach into PF reset flow

[Dawid Osuchowski <dawid.osuchowski@linux.intel.com>]

Ethtool callbacks can be executed while reset is in progress and try to
access deleted resources, e.g. getting coalesce settings can result in a
NULL pointer dereference seen below.

Reproduction steps:
Once the driver is fully initialized, trigger reset:
	# echo 1 > /sys/class/net/<interface>/device/reset
when reset is in progress try to get coalesce settings using ethtool:
	# ethtool -c <interface>

BUG: kernel NULL pointer dereference, address: 0000000000000020
PGD 0 P4D 0
Oops: Oops: 0000 [#1] PREEMPT SMP PTI
CPU: 11 PID: 19713 Comm: ethtool Tainted: G S                 6.10.0-rc7+ #7
RIP: 0010:ice_get_q_coalesce+0x2e/0xa0 [ice]
RSP: 0018:ffffbab1e9bcf6a8 EFLAGS: 00010206
RAX: 000000000000000c RBX: ffff94512305b028 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffff9451c3f2e588 RDI: ffff9451c3f2e588
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: ffff9451c3f2e580 R11: 000000000000001f R12: ffff945121fa9000
R13: ffffbab1e9bcf760 R14: 0000000000000013 R15: ffffffff9e65dd40
FS:  00007faee5fbe740(0000) GS:ffff94546fd80000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000020 CR3: 0000000106c2e005 CR4: 00000000001706f0
Call Trace:
<TASK>
ice_get_coalesce+0x17/0x30 [ice]
coalesce_prepare_data+0x61/0x80
ethnl_default_doit+0xde/0x340
genl_family_rcv_msg_doit+0xf2/0x150
genl_rcv_msg+0x1b3/0x2c0
netlink_rcv_skb+0x5b/0x110
genl_rcv+0x28/0x40
netlink_unicast+0x19c/0x290
netlink_sendmsg+0x222/0x490
__sys_sendto+0x1df/0x1f0
__x64_sys_sendto+0x24/0x30
do_syscall_64+0x82/0x160
entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7faee60d8e27

Calling netif_device_detach() before reset makes the net core not call
the driver when ethtool command is issued, the attempt to execute an
ethtool command during reset will result in the following message:

    netlink error: No such device

instead of NULL pointer dereference. Once reset is done and
ice_rebuild() is executing, the netif_device_attach() is called to allow
for ethtool operations to occur again in a safe manner.

Fixes: fcea6f3da546 ("ice: Add stats and ethtool support")
Suggested-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Igor Bagnucki <igor.bagnucki@intel.com>
Signed-off-by: Dawid Osuchowski <dawid.osuchowski@linux.intel.com>
---
Changes since v1:
* Changed Fixes tag to point to another commit
* Minified the stacktrace

Changes since v2:
* Moved netif_device_attach() directly into ice_rebuild() and perform it
  only on main vsi

Suggestion from Kuba: https://lore.kernel.org/netdev/20240610194756.5be5be90@kernel.org/
Previous attempt (dropped because it introduced regression with link up): https://lore.kernel.org/netdev/20240722122839.51342-1-dawid.osuchowski@linux.intel.com/
---
 drivers/net/ethernet/intel/ice/ice_main.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/net/ethernet/intel/ice/ice_main.c b/drivers/net/ethernet/intel/ice/ice_main.c
index eaa73cc200f4..27ec5d8d5810 100644
--- a/drivers/net/ethernet/intel/ice/ice_main.c
+++ b/drivers/net/ethernet/intel/ice/ice_main.c
@@ -608,6 +608,8 @@ ice_prepare_for_reset(struct ice_pf *pf, enum ice_reset_req reset_type)
 			memset(&vsi->mqprio_qopt, 0, sizeof(vsi->mqprio_qopt));
 		}
 	}
+	if (vsi->netdev)
+		netif_device_detach(vsi->netdev);
 skip:
 
 	/* clear SW filtering DB */
@@ -7731,6 +7733,10 @@ static void ice_rebuild(struct ice_pf *pf, enum ice_reset_req reset_type)
 		ice_rebuild_arfs(pf);
 	}
 
+	struct ice_vsi *vsi = ice_get_main_vsi(pf);
+	if (vsi && vsi->netdev)
+		netif_device_attach(vsi->netdev);
+
 	ice_update_pf_netdev_link(pf);
 
 	/* tell the firmware we are up */
-- 
2.44.0