Hi Greg KH,
Sorry for the confusion.
I tested the feature on linux-5.10, it will cause Oops.
The Oops is as follows:
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
Mem abort info:
ESR = 0x96000005
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
Data abort info:
ISV = 0, ISS = 0x00000005
CM = 0, WnR = 0
user pgtable: 4k pages, 39-bit VAs, pgdp=00000001b12cf000
[0000000000000000] pgd=0000000000000000, p4d=0000000000000000, pud=0000000000000000
Internal error: Oops: 96000005 [#1] PREEMPT SMP
Modules linked in: ...
CPU: 0 PID: 619 Comm: irq/95-20200080 Tainted: G O 5.10.61 #2
Hardware name: Ambarella CV5 TIMN Board (DT)
pstate: 20c00085 (nzCv daIf +PAN +UAO -TCO BTYPE=--)
pc : config_ep_by_speed_and_alt+0x3c/0x2a0 [libcomposite]
lr : config_ep_by_speed+0x14/0x20 [libcomposite]
sp : ffffffc011dbbac0
x29: ffffffc011dbbac0 x28: 0000000000000001
x27: ffffff81b3eb1920 x26: 0000000000000000
x25: ffffff81b68085e8 x24: ffffff81b3ee4c00
x23: ffffff81b3d71c40 x22: 0000000000000000
x21: 0000000000000000 x20: ffffff81b68085e8
x19: ffffff81b6808000 x18: ffffffc091dbb737
x17: 0000000000000017 x16: 000000000000000a
x15: 0000000000000006 x14: ffffffc011dbb73f
x13: 0000000000000001 x12: ffffffc0109c97e8
x11: 0000000000000652 x10: 00000000000e5a65
x9 : ffffffc0109c97e8 x8 : 00000000fffff7ff
x7 : 00000000000017fd x6 : 0000000000000001
x5 : ffffff81fb5976a8 x4 : 0000000000000006
x3 : 0000000000000000 x2 : ffffff81b6838718
x1 : 0000000000000000 x0 : ffffff81b6838008
Call trace:
config_ep_by_speed_and_alt+0x3c/0x2a0 [libcomposite]
uvc_function_set_alt+0xd4/0x2e8 [usb_f_uvc]
set_config.constprop.0+0x154/0x3a0 [libcomposite]
composite_setup+0x314/0xb44 [libcomposite]
configfs_composite_setup+0x84/0xb0 [libcomposite]
cdnsp_ep0_std_request+0x25c/0x470 [cdns3]
cdnsp_setup_analyze+0x94/0x25c [cdns3]
cdnsp_handle_event+0xe8/0x23c [cdns3]
cdnsp_thread_irq_handler+0x58/0xe8 [cdns3]
irq_thread_fn+0x2c/0xa0
irq_thread+0x164/0x280
kthread+0x128/0x134
ret_from_fork+0x10/0x40
Code: 71000c9f 54000b60 f9400821 52800006 (f9400024)
---[ end trace 7d3065b8181de7a6 ]---
note: irq/95-20200080[619] exited with preempt_count 2
genirq: exiting task "irq/95-20200080" (619) is an active IRQ thread (irq 95)
But the Oops is fixed in the latest kernel by the following commit:
commit 16d42759207fc3d1bff7cfd330a08a225e470ba0
Author: Qihang Hu <huqihang@xxxxxxxx>
Date: Wed Nov 10 18:11:29 2021 +0800
usb: gadget: composite: Show warning if function driver's descriptors are incomplete.
There are some problems with my previous understanding,
so the patch is a feature but not a bug, I will modify the
title and description of the patch and resend it.
Thanks
Jing Leng
