netdev - flexcan introduced a DIV/0 in kernel

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Message-ID: <5bdfcccb-0b02-e46b-eefe-7df215cc9d02@citymesh.com>
Date:   Fri, 9 Apr 2021 12:18:03 +0200
From:   Koen Vandeputte <koen.vandeputte@...ymesh.com>
To:     linux-can@...r.kernel.org
Cc:     wg@...ndegger.com, mkl@...gutronix.de, netdev@...r.kernel.org,
        qiangqing.zhang@....com, gregkh@...uxfoundation.org
Subject: flexcan introduced a DIV/0 in kernel

Hi All,

I just updated kernel 4.14 within OpenWRT from 4.14.224 to 4.14.229
Booting it shows the splat below on each run. [1]


It seems there are 2 patches regarding flexcan which were introduced in 
4.14.226

--> ce59ffca5c49 ("can: flexcan: enable RX FIFO after FRZ/HALT valid")
--> bb7c9039a396 ("can: flexcan: assert FRZ bit in flexcan_chip_freeze()")

Reverting these fixes the splat.

Hope this helps,

Koen



[1]

[   10.062140] flexcan 2090000.flexcan: 2090000.flexcan supply xceiver 
not found, using dummy regulator
[   10.071631] Division by zero in kernel.
[   10.075511] CPU: 0 PID: 1061 Comm: kmodloader Not tainted 4.14.229 #0
[   10.081981] Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
[   10.088529] Backtrace:
[   10.091040] [<8010ba30>] (dump_backtrace) from [<8010bdd4>] 
(show_stack+0x18/0x1c)
[   10.098631]  r7:9f5edc10 r6:60000013 r5:00000000 r4:80932c88
[   10.104336] [<8010bdbc>] (show_stack) from [<8063f8e0>] 
(dump_stack+0x9c/0xb0)
[   10.111591] [<8063f844>] (dump_stack) from [<8010bb90>] 
(__div0+0x1c/0x20)
[   10.118491]  r7:9f5edc10 r6:a0f0c000 r5:9ea3fd40 r4:9ea3f800
[   10.124199] [<8010bb74>] (__div0) from [<8063de94>] (Ldiv0+0x8/0x10)
[   10.130611] [<7f32b334>] (flexcan_mailbox_read [flexcan]) from 
[<7f32c480>] (flexcan_probe+0x360/0x468 [flexcan])
[   10.140902]  r7:9f5edc10 r6:a0f0c000 r5:9ea3fd40 r4:9ea3f800
[   10.146608] [<7f32c120>] (flexcan_probe [flexcan]) from [<8040f384>] 
(platform_drv_probe+0x60/0xb4)
[   10.155698]  r10:80903c08 r9:00000000 r8:0000000d r7:fffffdfb 
r6:7f32e014 r5:fffffffe
[   10.163562]  r4:9f5edc10
[   10.166117] [<8040f324>] (platform_drv_probe) from [<8040db78>] 
(driver_probe_device+0x154/0x2ec)
[   10.175012]  r7:7f32e014 r6:00000000 r5:9f5edc10 r4:80964928
[   10.180720] [<8040da24>] (driver_probe_device) from [<8040dd98>] 
(__driver_attach+0x88/0xac)
[   10.189195]  r9:7f32e080 r8:014000c0 r7:00000000 r6:9f5edc44 
r5:7f32e014 r4:9f5edc10
[   10.196985] [<8040dd10>] (__driver_attach) from [<8040bfc0>] 
(bus_for_each_dev+0x54/0xa8)
[   10.205199]  r7:00000000 r6:8040dd10 r5:7f32e014 r4:00000000
[   10.210891] [<8040bf6c>] (bus_for_each_dev) from [<8040d4ac>] 
(driver_attach+0x24/0x28)
[   10.218912]  r6:9e41e880 r5:8091b340 r4:7f32e014
[   10.223559] [<8040d488>] (driver_attach) from [<8040d0a0>] 
(bus_add_driver+0xf4/0x204)
[   10.231529] [<8040cfac>] (bus_add_driver) from [<8040e4e8>] 
(driver_register+0xb0/0xec)
[   10.239574]  r7:7f331000 r6:00000000 r5:ffffe000 r4:7f32e014
[   10.245266] [<8040e438>] (driver_register) from [<8040f2d4>] 
(__platform_driver_register+0x48/0x50)
[   10.254332]  r5:ffffe000 r4:80903c08
[   10.257953] [<8040f28c>] (__platform_driver_register) from 
[<7f331020>] (init_module+0x20/0x1000 [flexcan])
[   10.267729] [<7f331000>] (init_module [flexcan]) from [<80101a1c>] 
(do_one_initcall+0xc4/0x188)
[   10.276490] [<80101958>] (do_one_initcall) from [<80192458>] 
(do_init_module+0x68/0x204)
[   10.284615]  r9:7f32e080 r8:014000c0 r7:00000000 r6:9e48b640 
r5:9e4af000 r4:7f32e080
[   10.292389] [<801923f0>] (do_init_module) from [<801944b4>] 
(load_module+0x1e1c/0x220c)
[   10.300441]  r7:00000000 r6:9e4af1a8 r5:9e4af000 r4:9e8f3f30
[   10.306158] [<80192698>] (load_module) from [<80194a00>] 
(SyS_init_module+0x15c/0x17c)
[   10.314110]  r10:00000051 r9:000128ce r8:ffffe000 r7:001e545c 
r6:00000000 r5:a0f0945c
[   10.321957]  r4:0000345c
[   10.324541] [<801948a4>] (SyS_init_module) from [<801079e0>] 
(ret_fast_syscall+0x0/0x54)
[   10.332663]  r10:00000080 r9:9e8f2000 r8:80107be4 r7:00000080 
r6:00000003 r5:00000000
[   10.340511]  r4:00000000
[   10.344089] flexcan 2090000.flexcan: device registered 
(reg_base=a0f0c000, irq=33)