linux-kernel - Re: kernel 4.10-rcx iio helper question

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Message-ID: <D83D8851-7B2F-4F25-B0E0-2145BA7E8DBC@jic23.retrosnub.co.uk>
Date:   Tue, 31 Jan 2017 21:06:31 +0000
From:   Jonathan Cameron <jic23@...23.retrosnub.co.uk>
To:     "Ken.Lin" <ken.lin@...antech.com>,
        "jic23@...nel.org" <jic23@...nel.org>
CC:     "peda@...ntia.se" <peda@...ntia.se>,
        "knaack.h@....de" <knaack.h@....de>,
        "pmeerw@...erw.net" <pmeerw@...erw.net>,
        "linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Akshay Bhat <akshay.bhat@...esys.com>,
        "Peter.Stretz" <peter.stretz@...antech.com>,
        "Peter.Chiang" <peter.chiang@...antech.com>
Subject: Re: kernel 4.10-rcx iio helper question



On 31 January 2017 18:19:12 GMT+00:00, "Ken.Lin" <ken.lin@...antech.com> wrote:
>Hi,
>
>I find the latest kernel introduces new iio sys attributes.
>https://patchwork.kernel.org/patch/9391771/
>https://patchwork.kernel.org/patch/9391259/
> 
>Is there anyone has some ideas about how the new iio sys attribute -
>in_pressure_scale_available works?
>I'm not sure if it's the regression issue or it's just the usage issue
>or something when I tried to read in_pressure_scale_available
>attribute.
> 
># cat /sys/bus/iio/devices/iio\:device1/in_pressure_scale_available
>Segmentation fault

Hi Ken, what driver was this with?

Hardly any should be creating the attrs that use this at the moment.

Looks like something odd is going on.

Jonathan

> 
>[ 3785.077014] Unable to handle kernel NULL pointer dereference at
>virtual address 00000000
>[ 3785.085138] pgd = ecc3c000
>[ 3785.087929] [00000000] *pgd=87f91831
>[ 3785.091563] Internal error: Oops: 80000007 [#1] SMP ARM
>[ 3785.096806] Modules linked in:
>[ 3785.099892] CPU: 1 PID: 1051 Comm: cat Not tainted
>4.10.0-rc5-00009-gffd8858-dirty #3
>[ 3785.107740] Hardware name: Freescale i.MX6 Quad/DualLite (Device
>Tree)
>[ 3785.114285] task: ed54ec00 task.stack: ee2bc000
>[ 3785.118834] PC is at 0x0
>[ 3785.121397] LR is at iio_read_channel_info_avail+0x40/0x280
>[ 3785.126992] pc : [<00000000>]    lr : [<c06fbc1c>]    psr: a0070013
>[ 3785.126992] sp : ee2bdda8  ip : 00000000  fp : ee2bddf4
>[ 3785.138490] r10: c0a53c74  r9 : ed79f000  r8 : ee8d1018
>[ 3785.143733] r7 : 00001000  r6 : 00000fff  r5 : ee8b9a00  r4 :
>ed79f000
>[ 3785.150276] r3 : ee2bddc4  r2 : ee2bddbc  r1 : c0a86dcc  r0 :
>ee8d1000
>[ 3785.156820] Flags: NzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM 
>Segment none
>[ 3785.163971] Control: 10c5387d  Table: 3cc3c04a  DAC: 00000051
>[ 3785.169734] Process cat (pid: 1051, stack limit = 0xee2bc210)
>[ 3785.175497] Stack: (0xee2bdda8 to 0xee2be000)
>[ 3785.179880] dda0:                   ee2bddc0 00000002 c016d720
>c016d394 ed54ec00 00000000
>[ 3785.188084] ddc0: 60070013 ed413780 00000001 edffd480 ee8b9a00
>00000fff 00001000 ee8d1018
>[ 3785.196286] dde0: ed79f000 c0a53c74 ee2bde0c ee2bddf8 c0513c58
>c06fbbe8 edffd480 edffd540
>[ 3785.204488] de00: ee2bde3c ee2bde10 c0293474 c0513c40 c02933e4
>ee2bde60 00000001 ed413780
>[ 3785.212688] de20: 00000001 ed413780 00000000 edffd480 ee2bde4c
>ee2bde40 c0291d00 c02933f0
>[ 3785.220889] de40: ee2bde9c ee2bde50 c024679c c0291ce0 edffd4b0
>b6e37000 00020000 ee2bdf78
>[ 3785.229089] de60: 00000000 00000000 ed54ec00 ed013200 00000817
>c0a111fc edffd540 ed413780
>[ 3785.237289] de80: b6e37000 00020000 00020000 ee2bdf78 ee2bded4
>ee2bdea0 c0292890 c0246604
>[ 3785.245491] dea0: c0117940 c016ba50 00000025 c0a111fc b6e37000
>ed413780 ee2bdf78 00020000
>[ 3785.253691] dec0: ee2bc000 b6e37000 ee2bdf44 ee2bded8 c021d158
>c0292770 c0117764 b6e36004
>[ 3785.261893] dee0: c0f0d7c4 ee2bdfb0 b6f89228 00021008 ee2bdfac
>ee2bdf00 c0101374 c0117770
>[ 3785.270093] df00: 00000000 00000000 ee2bc000 00000000 ee2bdf34
>ee2bdf20 c016ba04 c0171080
>[ 3785.278292] df20: 00000000 00020000 ed413780 b6e37000 00000000
>ee2bdf78 ee2bdf74 ee2bdf48
>[ 3785.286493] df40: c021e7a0 c021d130 c023e300 c023e280 ee2bdf74
>00000000 00000000 ed413780
>[ 3785.294693] df60: ed413780 00020000 ee2bdfa4 ee2bdf78 c021e870
>c021e71c 00000000 00000000
>[ 3785.302892] df80: 00020000 00020000 b6e37000 00000003 c0108084
>00000000 00000000 ee2bdfa8
>[ 3785.311092] dfa0: c0107ee0 c021e838 00020000 00020000 00000003
>b6e37000 00020000 0001a2b4
>[ 3785.319292] dfc0: 00020000 00020000 b6e37000 00000003 7fffe000
>00000000 00000000 00020000
>[ 3785.327492] dfe0: 00000000 be98eb4c 0000c740 b6f1985c 60070010
>00000003 00000000 00000000
>[ 3785.335679] Backtrace:
>[ 3785.338175] [<c06fbbdc>] (iio_read_channel_info_avail) from
>[<c0513c58>] (dev_attr_show+0x24/0x50)
>[ 3785.347162]  r10:c0a53c74 r9:ed79f000 r8:ee8d1018 r7:00001000
>r6:00000fff r5:ee8b9a00
>[ 3785.355005]  r4:edffd480
>[ 3785.357571] [<c0513c34>] (dev_attr_show) from [<c0293474>]
>(sysfs_kf_seq_show+0x90/0x110)
>[ 3785.365764]  r5:edffd540 r4:edffd480
>[ 3785.369365] [<c02933e4>] (sysfs_kf_seq_show) from [<c0291d00>]
>(kernfs_seq_show+0x2c/0x30)
>[ 3785.377652]  r10:edffd480 r9:00000000 r8:ed413780 r7:00000001
>r6:ed413780 r5:00000001
>[ 3785.385498]  r4:ee2bde60 r3:c02933e4
>[ 3785.389101] [<c0291cd4>] (kernfs_seq_show) from [<c024679c>]
>(seq_read+0x1a4/0x4e0)
>[ 3785.396780] [<c02465f8>] (seq_read) from [<c0292890>]
>(kernfs_fop_read+0x12c/0x1cc)
>[ 3785.404460]  r10:ee2bdf78 r9:00020000 r8:00020000 r7:b6e37000
>r6:ed413780 r5:edffd540
>[ 3785.412303]  r4:c0a111fc
>[ 3785.414862] [<c0292764>] (kernfs_fop_read) from [<c021d158>]
>(__vfs_read+0x34/0x118)
>[ 3785.422627]  r10:b6e37000 r9:ee2bc000 r8:00020000 r7:ee2bdf78
>r6:ed413780 r5:b6e37000
>[ 3785.430470]  r4:c0a111fc
>[ 3785.433029] [<c021d124>] (__vfs_read) from [<c021e7a0>]
>(vfs_read+0x90/0x11c)
>[ 3785.440185]  r8:ee2bdf78 r7:00000000 r6:b6e37000 r5:ed413780
>r4:00020000
>[ 3785.446909] [<c021e710>] (vfs_read) from [<c021e870>]
>(SyS_read+0x44/0x90)
>[ 3785.453804]  r8:00020000 r7:ed413780 r6:ed413780 r5:00000000
>r4:00000000
>[ 3785.460537] [<c021e82c>] (SyS_read) from [<c0107ee0>]
>(ret_fast_syscall+0x0/0x1c)
>[ 3785.468042]  r10:00000000 r8:c0108084 r7:00000003 r6:b6e37000
>r5:00020000 r4:00020000
>[ 3785.476238] Code: bad PC value
>[ 3785.490358] ---[ end trace 9c4938ccd0389004 ]---
>
>Thank you
>
>Cheers,
>Ken Lin

-- 
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