wifi: mt76: disable napi on driver removal

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: wifi: mt76: disable napi on driver removal A warning on driver removal started occurring after commit 9dd05df8403b ("net: warn if NAPI instance wasn't shut down"). Disable tx napi before deleting it in mt76_dma_cleanup(). WARNING: CPU: 4 PID: 18828 at net/core/dev.c:7288 __netif_napi_del_locked+0xf0/0x100 CPU: 4 UID: 0 PID: 18828 Comm: modprobe Not tainted 6.15.0-rc4 #4 PREEMPT(lazy) Hardware name: ASUS System Product Name/PRIME X670E-PRO WIFI, BIOS 3035 09/05/2024 RIP: 0010:__netif_napi_del_locked+0xf0/0x100 Call Trace: <TASK> mt76_dma_cleanup+0x54/0x2f0 [mt76] mt7921_pci_remove+0xd5/0x190 [mt7921e] pci_device_remove+0x47/0xc0 device_release_driver_internal+0x19e/0x200 driver_detach+0x48/0x90 bus_remove_driver+0x6d/0xf0 pci_unregister_driver+0x2e/0xb0 __do_sys_delete_module.isra.0+0x197/0x2e0 do_syscall_64+0x7b/0x160 entry_SYSCALL_64_after_hwframe+0x76/0x7e Tested with mt7921e but the same pattern can be actually applied to other mt76 drivers calling mt76_dma_cleanup() during removal. Tx napi is enabled in their *_dma_init() functions and only toggled off and on again inside their suspend/resume/reset paths. So it should be okay to disable tx napi in such a generic way. Found by Linux Verification Center (linuxtesting.org).

References

• https://git.kernel.org/stable/c/ff0f820fa5b99035b3c654dd531226d8d83aec5f
• https://git.kernel.org/stable/c/ca5b213bf4b4224335a8131a26805d16503fca5f
• https://git.kernel.org/stable/c/b892e830d1ea8c5475254b98827771f7366f1039
• https://git.kernel.org/stable/c/5e700b06b970fc19e3a1ecb244e14785f3fbb8e3
• https://git.kernel.org/stable/c/2b81e76db3667d1f7f2ad44e9835cdaf8dea95a8
• https://git.kernel.org/stable/c/e7bfbda5fddd27f3158e723d641c0fcdfb0552a7
• https://git.kernel.org/stable/c/78ab4be549533432d97ea8989d2f00b508fa68d8