Remove redundant netif_napi_del() call from disconnect path.

A WARN may be triggered in __netif_napi_del_locked() during USB device
disconnect:

  WARNING: CPU: 0 PID: 11 at net/core/dev.c:7417 __netif_napi_del_locked+0x2b4/0x350

This happens because netif_napi_del() is called in the disconnect path while
NAPI is still enabled. However, it is not necessary to call netif_napi_del()
explicitly, since unregister_netdev() will handle NAPI teardown automatically
and safely. Removing the redundant call avoids triggering the warning.

Full trace:
 lan78xx 1-1:1.0 enu1: Failed to read register index 0x000000c4. ret = -ENODEV
 lan78xx 1-1:1.0 enu1: Failed to set MAC down with error -ENODEV
 lan78xx 1-1:1.0 enu1: Link is Down
 lan78xx 1-1:1.0 enu1: Failed to read register index 0x00000120. ret = -ENODEV
 ------------[ cut here ]------------
 WARNING: CPU: 0 PID: 11 at net/core/dev.c:7417 __netif_napi_del_locked+0x2b4/0x350
 Modules linked in: flexcan can_dev fuse
 CPU: 0 UID: 0 PID: 11 Comm: kworker/0:1 Not tainted 6.16.0-rc2-00624-ge926949dab03 #9 PREEMPT
 Hardware name: SKOV IMX8MP CPU revC - bd500 (DT)
 Workqueue: usb_hub_wq hub_event
 pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
 pc : __netif_napi_del_locked+0x2b4/0x350
 lr : __netif_napi_del_locked+0x7c/0x350
 sp : ffffffc085b673c0
 x29: ffffffc085b673c0 x28: ffffff800b7f2000 x27: ffffff800b7f20d8
 x26: ffffff80110bcf58 x25: ffffff80110bd978 x24: 1ffffff0022179eb
 x23: ffffff80110bc000 x22: ffffff800b7f5000 x21: ffffff80110bc000
 x20: ffffff80110bcf38 x19: ffffff80110bcf28 x18: dfffffc000000000
 x17: ffffffc081578940 x16: ffffffc08284cee0 x15: 0000000000000028
 x14: 0000000000000006 x13: 0000000000040000 x12: ffffffb0022179e8
 x11: 1ffffff0022179e7 x10: ffffffb0022179e7 x9 : dfffffc000000000
 x8 : 0000004ffdde8619 x7 : ffffff80110bcf3f x6 : 0000000000000001
 x5 : ffffff80110bcf38 x4 : ffffff80110bcf38 x3 : 0000000000000000
 x2 : 0000000000000000 x1 : 1ffffff0022179e7 x0 : 0000000000000000
 Call trace:
  __netif_napi_del_locked+0x2b4/0x350 (P)
  lan78xx_disconnect+0xf4/0x360
  usb_unbind_interface+0x158/0x718
  device_remove+0x100/0x150
  device_release_driver_internal+0x308/0x478
  device_release_driver+0x1c/0x30
  bus_remove_device+0x1a8/0x368
  device_del+0x2e0/0x7b0
  usb_disable_device+0x244/0x540
  usb_disconnect+0x220/0x758
  hub_event+0x105c/0x35e0
  process_one_work+0x760/0x17b0
  worker_thread+0x768/0xce8
  kthread+0x3bc/0x690
  ret_from_fork+0x10/0x20
 irq event stamp: 211604
 hardirqs last  enabled at (211603): [<ffffffc0828cc9ec>] _raw_spin_unlock_irqrestore+0x84/0x98
 hardirqs last disabled at (211604): [<ffffffc0828a9a84>] el1_dbg+0x24/0x80
 softirqs last  enabled at (211296): [<ffffffc080095f10>] handle_softirqs+0x820/0xbc8
 softirqs last disabled at (210993): [<ffffffc080010288>] __do_softirq+0x18/0x20
 ---[ end trace 0000000000000000 ]---
 lan78xx 1-1:1.0 enu1: failed to kill vid 0081/0

Fixes: ec4c7e1 ("lan78xx: Introduce NAPI polling support")
Suggested-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Link: https://patch.msgid.link/20250627051346.276029-1-o.rempel@pengutronix.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

A crash in conntrack was reported while trying to unlink the conntrack
entry from the hash bucket list:
    [exception RIP: __nf_ct_delete_from_lists+172]
    [..]
 #7 [ff539b5a2b043aa0] nf_ct_delete at ffffffffc124d421 [nf_conntrack]
 #8 [ff539b5a2b043ad0] nf_ct_gc_expired at ffffffffc124d999 [nf_conntrack]
 #9 [ff539b5a2b043ae0] __nf_conntrack_find_get at ffffffffc124efbc [nf_conntrack]
    [..]

The nf_conn struct is marked as allocated from slab but appears to be in
a partially initialised state:

 ct hlist pointer is garbage; looks like the ct hash value
 (hence crash).
 ct->status is equal to IPS_CONFIRMED|IPS_DYING, which is expected
 ct->timeout is 30000 (=30s), which is unexpected.

Everything else looks like normal udp conntrack entry.  If we ignore
ct->status and pretend its 0, the entry matches those that are newly
allocated but not yet inserted into the hash:
  - ct hlist pointers are overloaded and store/cache the raw tuple hash
  - ct->timeout matches the relative time expected for a new udp flow
    rather than the absolute 'jiffies' value.

If it were not for the presence of IPS_CONFIRMED,
__nf_conntrack_find_get() would have skipped the entry.

Theory is that we did hit following race:

cpu x 			cpu y			cpu z
 found entry E		found entry E
 E is expired		<preemption>
 nf_ct_delete()
 return E to rcu slab
					init_conntrack
					E is re-inited,
					ct->status set to 0
					reply tuplehash hnnode.pprev
					stores hash value.

cpu y found E right before it was deleted on cpu x.
E is now re-inited on cpu z.  cpu y was preempted before
checking for expiry and/or confirm bit.

					->refcnt set to 1
					E now owned by skb
					->timeout set to 30000

If cpu y were to resume now, it would observe E as
expired but would skip E due to missing CONFIRMED bit.

					nf_conntrack_confirm gets called
					sets: ct->status |= CONFIRMED
					This is wrong: E is not yet added
					to hashtable.

cpu y resumes, it observes E as expired but CONFIRMED:
			<resumes>
			nf_ct_expired()
			 -> yes (ct->timeout is 30s)
			confirmed bit set.

cpu y will try to delete E from the hashtable:
			nf_ct_delete() -> set DYING bit
			__nf_ct_delete_from_lists

Even this scenario doesn't guarantee a crash:
cpu z still holds the table bucket lock(s) so y blocks:

			wait for spinlock held by z

					CONFIRMED is set but there is no
					guarantee ct will be added to hash:
					"chaintoolong" or "clash resolution"
					logic both skip the insert step.
					reply hnnode.pprev still stores the
					hash value.

					unlocks spinlock
					return NF_DROP
			<unblocks, then
			 crashes on hlist_nulls_del_rcu pprev>

In case CPU z does insert the entry into the hashtable, cpu y will unlink
E again right away but no crash occurs.

Without 'cpu y' race, 'garbage' hlist is of no consequence:
ct refcnt remains at 1, eventually skb will be free'd and E gets
destroyed via: nf_conntrack_put -> nf_conntrack_destroy -> nf_ct_destroy.

To resolve this, move the IPS_CONFIRMED assignment after the table
insertion but before the unlock.

Pablo points out that the confirm-bit-store could be reordered to happen
before hlist add resp. the timeout fixup, so switch to set_bit and
before_atomic memory barrier to prevent this.

It doesn't matter if other CPUs can observe a newly inserted entry right
before the CONFIRMED bit was set:

Such event cannot be distinguished from above "E is the old incarnation"
case: the entry will be skipped.

Also change nf_ct_should_gc() to first check the confirmed bit.

The gc sequence is:
 1. Check if entry has expired, if not skip to next entry
 2. Obtain a reference to the expired entry.
 3. Call nf_ct_should_gc() to double-check step 1.

nf_ct_should_gc() is thus called only for entries that already failed an
expiry check. After this patch, once the confirmed bit check passes
ct->timeout has been altered to reflect the absolute 'best before' date
instead of a relative time.  Step 3 will therefore not remove the entry.

Without this change to nf_ct_should_gc() we could still get this sequence:

 1. Check if entry has expired.
 2. Obtain a reference.
 3. Call nf_ct_should_gc() to double-check step 1:
    4 - entry is still observed as expired
    5 - meanwhile, ct->timeout is corrected to absolute value on other CPU
      and confirm bit gets set
    6 - confirm bit is seen
    7 - valid entry is removed again

First do check 6), then 4) so the gc expiry check always picks up either
confirmed bit unset (entry gets skipped) or expiry re-check failure for
re-inited conntrack objects.

This change cannot be backported to releases before 5.19. Without
commit 8a75a2c ("netfilter: conntrack: remove unconfirmed list")
|= IPS_CONFIRMED line cannot be moved without further changes.

Cc: Razvan Cojocaru <rzvncj@gmail.com>
Link: https://lore.kernel.org/netfilter-devel/20250627142758.25664-1-fw@strlen.de/
Link: https://lore.kernel.org/netfilter-devel/4239da15-83ff-4ca4-939d-faef283471bb@gmail.com/
Fixes: 1397af5 ("netfilter: conntrack: remove the percpu dying list")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

BUG: kernel NULL pointer dereference, address: 00000000000002ec
PGD 0 P4D 0
Oops: Oops: 0000 [#1] SMP PTI
CPU: 28 UID: 0 PID: 343 Comm: kworker/28:1 Kdump: loaded Tainted: G        OE       6.17.0-rc2+ #9 NONE
Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1 04/01/2014
Workqueue: smc_hs_wq smc_listen_work [smc]
RIP: 0010:smc_ib_is_sg_need_sync+0x9e/0xd0 [smc]
...
Call Trace:
 <TASK>
 smcr_buf_map_link+0x211/0x2a0 [smc]
 __smc_buf_create+0x522/0x970 [smc]
 smc_buf_create+0x3a/0x110 [smc]
 smc_find_rdma_v2_device_serv+0x18f/0x240 [smc]
 ? smc_vlan_by_tcpsk+0x7e/0xe0 [smc]
 smc_listen_find_device+0x1dd/0x2b0 [smc]
 smc_listen_work+0x30f/0x580 [smc]
 process_one_work+0x18c/0x340
 worker_thread+0x242/0x360
 kthread+0xe7/0x220
 ret_from_fork+0x13a/0x160
 ret_from_fork_asm+0x1a/0x30
 </TASK>

If the software RoCE device is used, ibdev->dma_device is a null pointer.
As a result, the problem occurs. Null pointer detection is added to
prevent problems.

Fixes: 0ef69e7 ("net/smc: optimize for smc_sndbuf_sync_sg_for_device and smc_rmb_sync_sg_for_cpu")
Signed-off-by: Liu Jian <liujian56@huawei.com>
Reviewed-by: Guangguan Wang <guangguan.wang@linux.alibaba.com>
Reviewed-by: Zhu Yanjun <yanjun.zhu@linux.dev>
Reviewed-by: D. Wythe <alibuda@linux.alibaba.com>
Link: https://patch.msgid.link/20250828124117.2622624-1-liujian56@huawei.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>