[PATCH v2] ppc: cpufreq: disable preemption while checking CPU throttling state

[Denis Kirjanov]

On 11/7/16, Michael Ellerman <mpe at ellerman.id.au> wrote:
> Denis Kirjanov <kda at linux-powerpc.org> writes:
>
>>     [   67.700897] BUG: using smp_processor_id() in preemptible [00000000]
>> code: cat/7343
>>     [   67.700988] caller is .powernv_cpufreq_throttle_check+0x2c/0x710
>>     [   67.700998] CPU: 13 PID: 7343 Comm: cat Not tainted 4.8.0-rc5-dirty
>> #1
>>     [   67.701038] Call Trace:
>>     [   67.701066] [c0000007d25b75b0] [c000000000971378]
>> .dump_stack+0xe4/0x150 (unreliable)
>>     [   67.701153] [c0000007d25b7640] [c0000000005162e4]
>> .check_preemption_disabled+0x134/0x150
>>     [   67.701238] [c0000007d25b76e0] [c0000000007b63ac]
>> .powernv_cpufreq_throttle_check+0x2c/0x710
>>     [   67.701322] [c0000007d25b7790] [c0000000007b6d18]
>> .powernv_cpufreq_target_index+0x288/0x360
>>     [   67.701407] [c0000007d25b7870] [c0000000007acee4]
>> .__cpufreq_driver_target+0x394/0x8c0
>>     [   67.701491] [c0000007d25b7920] [c0000000007b22ac]
>> .cpufreq_set+0x7c/0xd0
>>     [   67.701565] [c0000007d25b79b0] [c0000000007adf50]
>> .store_scaling_setspeed+0x80/0xc0
>>     [   67.701650] [c0000007d25b7a40] [c0000000007ae270]
>> .store+0xa0/0x100
>>     [   67.701723] [c0000007d25b7ae0] [c0000000003566e8]
>> .sysfs_kf_write+0x88/0xb0
>>     [   67.701796] [c0000007d25b7b70] [c0000000003553b8]
>> .kernfs_fop_write+0x178/0x260
>>     [   67.701881] [c0000007d25b7c10] [c0000000002ac3cc]
>> .__vfs_write+0x3c/0x1c0
>>     [   67.701954] [c0000007d25b7cf0] [c0000000002ad584]
>> .vfs_write+0xc4/0x230
>>     [   67.702027] [c0000007d25b7d90] [c0000000002aeef8]
>> .SyS_write+0x58/0x100
>>     [   67.702101] [c0000007d25b7e30] [c00000000000bfec]
>> system_call+0x38/0xfc
>>
>> Signed-off-by: Denis Kirjanov <kda at linux-powerpc.org>
>>
>> v2:  wrap powernv_cpufreq_throttle_check()
>> as suggested by Gautham R Shenoy
>
> That should be below the "---".
>
> When did this break?

I think that problem exists since commit
09a972d1620934142d30cfda455ffe429af751c4 ("cpufreq: powernv: Report
cpu frequency throttling") but I can be wrong
>
> cheers
>