Re: [BISECTED] Regression v4.6-rc1 : nanosleep doesn't return on AT91SAM9

[Nicolas Ferre]

Le 10/05/2016 16:59, Richard Genoud a Ãcrit :
> 2016-05-10 16:47 GMT+02:00 Boris Brezillon <boris.brezillon@xxxxxxxxxxxxxxxxxx>:
>> Hi Richard,
>>
>> On Tue, 10 May 2016 16:25:25 +0200
>> Richard Genoud <richard.genoud@xxxxxxxxx> wrote:
>>
>>> 2016-05-10 15:58 GMT+02:00 Richard Genoud <richard.genoud@xxxxxxxxx>:
>>>> Hi,
>>>>
>>>> Starting with 4.6-rc1, a sleep 1 doesn't return :
>>>>
>>>> execve("/bin/sleep", ["sleep", "1"], ["USER=root", "SHLVL=1",
>>>> "OLDPWD=/var", "HOME=/", "TERM=vt102",
>>>> "PATH=/sbin:/usr/sbin:/bin:/usr/bin", "SHELL=/bin/sh", "PWD=/"]) = 0
>>>> uname({sysname="Linux", nodename="LNS",
>>>> release="4.5.0-09406-g46e595a17dcf", version="#72 Tue May 10 15:41:34
>>>> CEST 2016", machine="armv5tejl", domainname="(none)"}) = 0
>>>> brk(0)                                  = 0x153000
>>>> brk(0x153d20)                           = 0x153d20
>>>> set_tls(0x1534c0, 0x14d1e4, 0, 0x153d20, 0x14e368) = 0
>>>> readlink("/proc/self/exe", "/bin/busybox", 4096) = 12
>>>> brk(0x174d20)                           = 0x174d20
>>>> brk(0x175000)                           = 0x175000
>>>> getuid32()                              = 0
>>>> rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0
>>>> rt_sigaction(SIGCHLD, NULL, {SIG_DFL, [], 0}, 8) = 0
>>>> rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
>>>> nanosleep({1, 0},
>>>>
>>>> And the heartbeat led doesn't blink anymore (full on), as if the
>>>> timers never fire.
>>>>
>>>> The platform is an AT91SAM9G35-CM.
>>>>
>>>> git bisect gives a merge as the 1st bad commit :(
>>>> first bad commit: [46e595a17dcf11404f713845ecb5b06b92a94e43] Merge tag
>>>> 'armsoc-drivers' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc
>>>
>>>
>>> I went a little further in tracking that down, starting from the merge
>>> (1st bad commit) and reverting some commits.
>>> It seems that the culprit is :
>>> commit 863a81c3be1d931bdae6426e231add9334311f13
>>> Author: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxxxxxxx>
>>> Date:   Fri Sep 5 09:54:13 2014 +0200
>>>     clk: at91: make use of syscon to share PMC registers in several drivers
>>>
>>> Here are the commits I've reverted :
>>>
>>> git log --oneline --decorate -20
>>> 849cdaa0cf04 (HEAD, tag: good) Revert "clk: at91: make use of syscon
>>> to share PMC registers in several drivers"
>>> 4bd6dde95321 (tag: last_bad) Revert "clk: at91: make use of
>>> syscon/regmap internally"
>>> a56dacaa24c4 (tag: always_bad) Revert "clk: at91: remove IRQ handling
>>> and use polling"
>>> 33edfe7a2de6 Revert "clk: at91: pmc: merge at91_pmc_init in atmel_pmc_probe"
>>> 0b22bb649eae Revert "clk: at91: pmc: move pmc structures to C file"
>>> 14994fdff366 Revert "ARM: at91: pm: simply call at91_pm_init"
>>> 6f0821175327 (tag: still_bad) Revert "ARM: at91: pm: find and remap the pmc"
>>> b52bbf7fad1b Revert "ARM: at91: pm: move idle functions to pm.c"
>>> dffb1a5f68b9 Revert "ARM: at91: remove useless includes and function prototypes"
>>> db352691dcc1 Revert "usb: gadget: atmel: access the PMC using regmap"
>>> f7b5433dbbc8 Revert "clk: at91: pmc: drop at91_pmc_base"
>>> 6e6dfc0d91c0 Revert "clk: at91: pmc: remove useless capacities handling"
>>> ceddd3f88ada Revert "clk: at91: remove useless includes"
>>> 46e595a17dcf (tag: bad) Merge tag 'armsoc-drivers' of
>>> git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc
>>> e3b1f64e04f5 Merge tag 'armsoc-defconfig' of
>>> git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc
>>> 915c56bc01d6 Merge tag 'armsoc-dt64' of
>>> git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc
>>> 5a6b7e53d035 Merge tag 'armsoc-dt' of
>>> git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc
>>> 8c6d4082fc6a Merge tag 'armsoc-arm64' of
>>> git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc
>>> 33b3d2e88c9e Merge tag 'armsoc-soc' of
>>> git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc
>>> e88fa1b8b00a Merge tag 'armsoc-cleanup' of
>>> git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc
>>
>> Thanks for the detailed report.
>>
>> Can you try again after applying this patch [1]?
>>
>> Regards,
>>
>> Boris
>>
>> [1]http://code.bulix.org/dx1c0t-98377
> 
> Yes, it works.
> Big thumbs up, that was fast !
> 
> Less than 1 hour between the report and the patch ! :)

Yes, absolutely terrific! Thanks Boris.

I'd like you to test with this instead as it's the real range of the IP:
+ reg = <0xfffffc00 0x110>;

Even I'm pretty confident ;-) Can you please do this for us ?

> This is clearly 4.6 material (as it's a regression from 4.5), but it's
> maybe a little late.
> Anrd, Nicolas, what do you think ?

I sent a PR this morning to Arnd with a "fix"... I hope that he won't be
annoyed if I send him another one this evening...  But clearly, it's a
regression and a pretty bad one :-\

Thanks a lot for this report Richard,
-- 
Nicolas Ferre