This reverts commit 13b7e6a96a.
That commit made mt76_dma_cleanup() disable every RX NAPI instance before
deleting it, to silence WARNs in __netif_napi_del_locked() and
page_pool_disable_direct_recycling() seen when unloading mt7915e with an
MT7916.
On mt7921e and mt7925e the same instances are already disabled earlier,
in mt7921e_unregister_device() and mt7925e_unregister_device(), which
only afterwards call mt792x_dma_cleanup() -> mt76_dma_cleanup(). Each
instance is therefore disabled twice, and napi_disable() is not
idempotent: on return it leaves NAPIF_STATE_SCHED and NAPIF_STATE_NPSVC
set, so the second call spins in usleep_range() forever, waiting for bits
that nobody will clear.
mt7921_pci_shutdown() and mt7925_pci_shutdown() reuse the remove path, so
this is hit on every reboot, poweroff and module unload. It is silent:
the stuck task keeps sleeping and rescheduling, so neither the hung task
detector nor the lockup detectors fire, and the last line on the console
is "systemd-shutdown[1]: Rebooting."
task:modprobe state:D stack:25720 pid:7954 tgid:7954
Call Trace:
<TASK>
__schedule+0x11b8/0x26d0
schedule+0xe7/0x2f0
schedule_hrtimeout_range_clock+0x218/0x330
usleep_range_state+0x133/0x1b0
napi_disable_locked+0x37d/0x5f0
napi_disable+0x43/0x80
mt76_dma_cleanup+0x2b4/0x860 [mt76]
mt7921_pci_remove+0x17f/0x350 [mt7921e]
pci_device_remove+0xb6/0x1e0
device_release_driver_internal+0x38d/0x540
driver_detach+0xd0/0x1b0
bus_remove_driver+0x127/0x2d0
pci_unregister_driver+0x2a/0x280
__do_sys_delete_module+0x36a/0x5b0
do_syscall_64+0x11c/0x6d0
entry_SYSCALL_64_after_hwframe+0x76/0x7e
</TASK>
Dropping the two driver-side loops instead was tried and rejected: with
them gone, the RX poll can reach mt76_token_release() via
PKT_TYPE_TXRX_NOTIFY and mt7921_mac_tx_free() while
mt76_connac2_tx_token_put() is running idr_destroy(&dev->token) outside
token_lock, which is a use-after-free rather than a hang [1].
Revert for now, so that reboot, poweroff and module unload work again.
The WARNs on mt7915e are a less severe problem than an unbootable
machine, and fixing them belongs in the drivers that delete the NAPI
instances, where each one can pick a point that is safe for its own
teardown order, rather than in the shared mt76_dma_cleanup().
[ This is the "landing soonish" known regression fix mentioned in the
previous networking merge commit - Linus ]
Reported-by: Bert Karwatzki <spasswolf@web.de>
Closes: https://lore.kernel.org/all/20260724151419.26014-1-spasswolf@web.de/
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=221818
Link: https://lore.kernel.org/all/20260730050428.GA73812@sol/ [1]
Signed-off-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Acked-by: Nicolas Cavallari <nicolas.cavallari@green-communications.fr>
Fixes: 13b7e6a96a ("wifi: mt76: Disable napi when removing device")
Tested-by: Devin Wittmayer <lucid_duck@justthetip.ca>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
3aa1dcaa4f