[Bug 11139] New: warning in cpufreq.c on E450

[Bug 11139] New: warning in cpufreq.c on E450

[bugme-daemon]

http://bugzilla.kernel.org/show_bug.cgi?id=11139

           Summary: warning in cpufreq.c on E450
           Product: Power Management
           Version: 2.5
     KernelVersion: 2.6.26
          Platform: All
        OS/Version: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: cpufreq
        AssignedTo: cpufreq@www.linux.org.uk
        ReportedBy: marvin@mydatex.cz


Latest working kernel version: 2.6.24.2
Earliest failing kernel version: 2.6.26
Distribution: Debian Sid
Hardware Environment: Sun E450/2x CPU 400Mhz/1GB Ram
Software Environment: Sid
Problem Description:
After I compile 2.6.26 an boots I get this:
------------[ cut here ]------------                                            
WARNING: at drivers/cpufreq/cpufreq.c:1391
cpufreq_register_notifier+0x50/0x60()
Modules linked in:                                                              
Call Trace:                                                                     
 [0000000000605270] cpufreq_register_notifier+0x58/0x60                         
 [00000000007708e0] start_kernel+0x1f0/0x324                                    
 [0000000000680e08] auxio_probe+0x0/0xe8                                        
 [0000000000000000] 0x8                                                         
---[ end trace 139ce121c98e96c9 ]---

Steps to reproduce:
Compile kernel with cpufreq enabled and boot.


-- 
Configure bugmail: http://bugzilla.kernel.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug, or are watching the assignee.

[Bug 11139] warning in cpufreq.c on E450

[bugme-daemon]

http://bugzilla.kernel.org/show_bug.cgi?id=11139


bunk@kernel.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bunk@kernel.org
         Regression|0                           |1




-- 
Configure bugmail: http://bugzilla.kernel.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug, or are watching the assignee.

[Bug 11139] warning in cpufreq.c on E450

[bugme-daemon]

http://bugzilla.kernel.org/show_bug.cgi?id=11139





------- Comment #1 from linux@brodo.de  2008-07-22 16:45 -------
This looks strange.

The warning is because init_cpufreq_transition_notifier_list_called is not set
to true (yet). However, that should have been done in pure_initcall stage which
is waaaaay before auxio_probe, which is at fs_initcall stage. Any experts on
the ordering of initcalls, and why this is messed up here?


-- 
Configure bugmail: http://bugzilla.kernel.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug, or are watching the assignee.

[Bug 11139] warning in cpufreq.c on E450

[bugme-daemon]

http://bugzilla.kernel.org/show_bug.cgi?id=11139





------- Comment #2 from cesarb@cesarb.net  2008-07-22 17:38 -------
There's another auxio_probe, at arch/sparc/kernel/auxio.c, which seems to be
called deep within setup_arch() if I followed the code paths correctly. The one
called at fs_initcall is the one at arch/sparc64/kernel/auxio.c.

This is probably not a regression; the warning was added after 2.6.25 (see
commit 74212ca432982903d0fc6a0f282b199e000ad8b1). The bug probably was there
all the time.


-- 
Configure bugmail: http://bugzilla.kernel.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug, or are watching the assignee.

[Bug 11139] warning in cpufreq.c on E450

[bugme-daemon]

http://bugzilla.kernel.org/show_bug.cgi?id=11139





------- Comment #3 from bunk@kernel.org  2008-07-23 02:04 -------
(In reply to comment #1)
> This looks strange.
> 
> The warning is because init_cpufreq_transition_notifier_list_called is not set
> to true (yet). However, that should have been done in pure_initcall stage which
> is waaaaay before auxio_probe, which is at fs_initcall stage. Any experts on
> the ordering of initcalls, and why this is messed up here?

cpufreq_register_notifier() is called by arch/sparc64/kernel/time.c:time_init()
which runs before the normal initcalls.


-- 
Configure bugmail: http://bugzilla.kernel.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug, or are watching the assignee.

[Bug 11139] warning in cpufreq.c on E450

[bugme-daemon]

http://bugzilla.kernel.org/show_bug.cgi?id=11139





------- Comment #4 from cesarb@cesarb.net  2008-07-23 03:54 -------
(In reply to comment #3)
> (In reply to comment #1)
> > This looks strange.
> > 
> > The warning is because init_cpufreq_transition_notifier_list_called is not set
> > to true (yet). However, that should have been done in pure_initcall stage which
> > is waaaaay before auxio_probe, which is at fs_initcall stage. Any experts on
> > the ordering of initcalls, and why this is messed up here?
> 
> cpufreq_register_notifier() is called by arch/sparc64/kernel/time.c:time_init()
> which runs before the normal initcalls.
> 

So, it's time again. I made the patch to add that warning because I made the
same mistake on my s3c2410 cpufreq work (trying to register a transition
notifier in the time setup code). The way I solved it was to move the cpufreq
notifier registration for the time code to a separate function on the same
file, which is called as a initcall. Since cpufreq doesn't actually do anything
until late in the initcall sequence (or even later) because it needs the
cpufreq cpu driver (which is usually a very late initcall or even a module), it
causes no problem (except that now the notifier actually runs, which could
expose untested code paths).


-- 
Configure bugmail: http://bugzilla.kernel.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug, or are watching the assignee.

[Bug 11139] warning in cpufreq.c on E450

[bugme-daemon]

http://bugzilla.kernel.org/show_bug.cgi?id=11139





------- Comment #5 from linux@brodo.de  2008-07-23 11:58 -------
Created an attachment (id=16954)
 --> (http://bugzilla.kernel.org/attachment.cgi?id=16954&action=view)
bugfix -- register cpufreq notifier later

cpufreq notifiers may only be registered after pure_initcall.


-- 
Configure bugmail: http://bugzilla.kernel.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug, or are watching the assignee.