Bug 41742

Summary: duplicate filename for intel_backlight with the i915 driver
Product: Drivers Reporter: François Valenduc (francoisvalenduc)
Component: Video(DRI - Intel)Assignee: drivers_video-dri-intel (drivers_video-dri-intel)
Status: CLOSED CODE_FIX    
Severity: normal CC: florian, maciej.rutecki, mjg59-kernel, rjw
Priority: P1    
Hardware: All   
OS: Linux   
Kernel Version: 3.1-rc3 Subsystem:
Regression: Yes Bisected commit-id:
Bug Depends on:    
Bug Blocks: 40982    

Description François Valenduc 2011-08-25 18:51:28 UTC 
I get this warning in dmesg with the i915 driver:

0.854960] ------------[ cut here ]------------
[    0.855026] WARNING: at fs/sysfs/dir.c:455 sysfs_add_one+0xbd/0xf0()
[    0.855091] Hardware name: Satellite L670
[    0.855148] sysfs: cannot create duplicate filename '/devices/pci0000:00/0000:00:02.0/drm/card0/card0-LVDS-1/intel_backlight'
[    0.855247] Modules linked in:
[    0.855327] Pid: 1, comm: swapper Not tainted 3.1.0-rc3 #1
[    0.855390] Call Trace:
[    0.855448]  [<ffffffff81035dbb>] ? warn_slowpath_common+0x7b/0xc0
[    0.855510]  [<ffffffff81035eb5>] ? warn_slowpath_fmt+0x45/0x50
[    0.855573]  [<ffffffff8114229d>] ? sysfs_add_one+0xbd/0xf0
[    0.855639]  [<ffffffff81142d79>] ? create_dir+0x79/0xe0
[    0.855701]  [<ffffffff81142e52>] ? sysfs_create_dir+0x72/0xc0
[    0.855781]  [<ffffffff81177c15>] ? kobject_add_internal+0xb5/0x200
[    0.855843]  [<ffffffff81177f66>] ? kobject_add+0x46/0x70
[    0.855908]  [<ffffffff8126e649>] ? device_add+0xa9/0x6a0
[    0.855970]  [<ffffffff81028720>] ? complete_all+0x40/0x60
[    0.856034]  [<ffffffff811dea26>] ? backlight_device_register+0xf6/0x1d0
[    0.856102]  [<ffffffff8125e53f>] ? intel_panel_setup_backlight+0x6f/0xe0
[    0.856169]  [<ffffffff8124a629>] ? intel_modeset_init+0x7c9/0x10f0
[    0.856233]  [<ffffffff8122c861>] ? i915_driver_load+0xcd1/0x11d0
[    0.856298]  [<ffffffff811788e9>] ? kobject_uevent_env+0x1d9/0x480
[    0.856364]  [<ffffffff81219ada>] ? drm_get_minor+0x1aa/0x2b0
[    0.856427]  [<ffffffff8121bc58>] ? drm_get_pci_dev+0x198/0x2c0
[    0.856495]  [<ffffffff81278e6b>] ? __pm_runtime_set_status+0x18b/0x230
[    0.856561]  [<ffffffff81199625>] ? local_pci_probe+0x55/0xd0
[    0.857217]  [<ffffffff8119a52c>] ? pci_device_probe+0x8c/0xc0
[    0.857284]  [<ffffffff81270bb2>] ? driver_sysfs_add+0x72/0xa0
[    0.857347]  [<ffffffff81270cf6>] ? driver_probe_device+0x96/0x1c0
[    0.857412]  [<ffffffff81270eb3>] ? __driver_attach+0x93/0xa0
[    0.857474]  [<ffffffff81270e20>] ? driver_probe_device+0x1c0/0x1c0
[    0.857541]  [<ffffffff81270428>] ? bus_for_each_dev+0x58/0x80
[    0.857604]  [<ffffffff8126fce8>] ? bus_add_driver+0x198/0x260
[    0.857671]  [<ffffffff814f132a>] ? drm_core_init+0x108/0x108
[    0.857732]  [<ffffffff812714c0>] ? driver_register+0x70/0x130
[    0.857801]  [<ffffffff814f132a>] ? drm_core_init+0x108/0x108
[    0.857865]  [<ffffffff8119a7dc>] ? __pci_register_driver+0x4c/0xc0
[    0.857930]  [<ffffffff810001ca>] ? do_one_initcall+0x3a/0x170
[    0.857999]  [<ffffffff814d05b6>] ? kernel_init+0x90/0x10e
[    0.858062]  [<ffffffff81350274>] ? kernel_thread_helper+0x4/0x10
[    0.858126]  [<ffffffff814d0526>] ? parse_early_options+0x20/0x20
[    0.858190]  [<ffffffff81350270>] ? gs_change+0xb/0xb
[    0.858254] ---[ end trace b2296b39a6e7298d ]---
[    0.858314] kobject_add_internal failed for intel_backlight with -EEXIST, don't try to register things with the same name in the same directory.
[    0.858418] Pid: 1, comm: swapper Tainted: G        W   3.1.0-rc3 #1
[    0.858484] Call Trace:
[    0.858536]  [<ffffffff81177cba>] ? kobject_add_internal+0x15a/0x200
[    0.858601]  [<ffffffff81177f66>] ? kobject_add+0x46/0x70
[    0.858666]  [<ffffffff8126e649>] ? device_add+0xa9/0x6a0
[    0.858727]  [<ffffffff81028720>] ? complete_all+0x40/0x60
[    0.858795]  [<ffffffff811dea26>] ? backlight_device_register+0xf6/0x1d0
[    0.858861]  [<ffffffff8125e53f>] ? intel_panel_setup_backlight+0x6f/0xe0
[    0.858927]  [<ffffffff8124a629>] ? intel_modeset_init+0x7c9/0x10f0
[    0.858991]  [<ffffffff8122c861>] ? i915_driver_load+0xcd1/0x11d0
[    0.859054]  [<ffffffff811788e9>] ? kobject_uevent_env+0x1d9/0x480
[    0.859119]  [<ffffffff81219ada>] ? drm_get_minor+0x1aa/0x2b0
[    0.859184]  [<ffffffff8121bc58>] ? drm_get_pci_dev+0x198/0x2c0
[    0.859246]  [<ffffffff81278e6b>] ? __pm_runtime_set_status+0x18b/0x230
[    0.859312]  [<ffffffff81199625>] ? local_pci_probe+0x55/0xd0
[    0.859377]  [<ffffffff8119a52c>] ? pci_device_probe+0x8c/0xc0
[    0.859442]  [<ffffffff81270bb2>] ? driver_sysfs_add+0x72/0xa0
[    0.859506]  [<ffffffff81270cf6>] ? driver_probe_device+0x96/0x1c0
[    0.859571]  [<ffffffff81270eb3>] ? __driver_attach+0x93/0xa0
[    0.859637]  [<ffffffff81270e20>] ? driver_probe_device+0x1c0/0x1c0
[    0.859702]  [<ffffffff81270428>] ? bus_for_each_dev+0x58/0x80
[    0.859774]  [<ffffffff8126fce8>] ? bus_add_driver+0x198/0x260
[    0.859838]  [<ffffffff814f132a>] ? drm_core_init+0x108/0x108
[    0.859902]  [<ffffffff812714c0>] ? driver_register+0x70/0x130
[    0.859966]  [<ffffffff814f132a>] ? drm_core_init+0x108/0x108
[    0.860028]  [<ffffffff8119a7dc>] ? __pci_register_driver+0x4c/0xc0
[    0.860092]  [<ffffffff810001ca>] ? do_one_initcall+0x3a/0x170
[    0.860154]  [<ffffffff814d05b6>] ? kernel_init+0x90/0x10e
[    0.860215]  [<ffffffff81350274>] ? kernel_thread_helper+0x4/0x10
[    0.860279]  [<ffffffff814d0526>] ? parse_early_options+0x20/0x20
[    0.860342]  [<ffffffff81350270>] ? gs_change+0xb/0xb
[    0.860402] [drm:intel_panel_setup_backlight] *ERROR* Failed to register backlight: -17


It doesn't seems to cause a real problem but can somebody explain what's happening ?
Comment 1 François Valenduc 2011-08-27 18:25:37 UTC 
A git bisect run reveals that the following commit  is problematic;

commit aaa6fd2a004147bf32fce05720938236de3361d9
Author: Matthew Garrett <mjg@redhat.com>
Date:   Fri Aug 12 12:11:33 2011 +0200

    Not all systems expose a firmware or platform mechanism for changing the backlight intensity on i915, so add native driver support.

Indeed, if I revert it, the problem doesn't occur.
Comment 2 Rafael J. Wysocki 2011-08-28 19:01:27 UTC 
First-Bad-Commit : aaa6fd2a004147bf32fce05720938236de3361d9
Comment 3 Rafael J. Wysocki 2011-08-28 19:39:54 UTC 
On Sunday, August 28, 2011, Dave Jones wrote:
> On Sun, Aug 28, 2011 at 08:22:05PM +0200, Rafael J. Wysocki wrote:
>  
>  > Bug-Entry  : http://bugzilla.kernel.org/show_bug.cgi?id=41742
>  > Subject            : duplicate filename  for intel_backlight with the i915
>  driver
>  > Submitter  : François Valenduc <francois.valenduc@tvcablenet.be>
>  > Date               : 2011-08-25 18:51 (4 days old)
>  > First-Bad-Commit:
>  http://git.kernel.org/linus/aaa6fd2a004147bf32fce05720938236de3361d9
>  
> this should be fixed by b727d20269e8ef1de002bfea8099f5e9db9e9f23
>  
>       Dave
Comment 4 Rafael J. Wysocki 2011-08-28 19:52:50 UTC 
On Sunday, August 28, 2011, Linus Torvalds wrote:
> On Sun, Aug 28, 2011 at 12:35 PM, Dave Jones <davej@redhat.com> wrote:
> > On Sun, Aug 28, 2011 at 08:22:05PM +0200, Rafael J. Wysocki wrote:
> >
> >  > Bug-Entry    : http://bugzilla.kernel.org/show_bug.cgi?id=41742
> >  > Subject              : duplicate filename  for intel_backlight with the
> i915 driver
> >  > Submitter    : François Valenduc <francois.valenduc@tvcablenet.be>
> >  > Date         : 2011-08-25 18:51 (4 days old)
> >  > First-Bad-Commit:
> http://git.kernel.org/linus/aaa6fd2a004147bf32fce05720938236de3361d9
> >
> > this should be fixed by b727d20269e8ef1de002bfea8099f5e9db9e9f23
> 
> Actually, by a2cc797d2d1a ("i915: do not setup intel_backlight ").
> 
> That b727d20269e is just my merge commit that brings in the fix (and
> the bogus initialization of 'locked') into mainline.
> 
>                    Linus