[LTP] Question about kernel/syscall/signal/signal06.c

[Hongzhi, Song]

This case fails when boot qemux86-64 with 1/2 cores.

I find [kernel 5.2-rc1: 0d714dba162] causes the failure by git bisect.

If git checkout a commit before 0d714dba162, the case will pass on the 
same qemu configuration.


--Hongzhi


On 7/17/19 5:46 PM, Cyril Hrubis wrote:
> Hi!
>> I find signal06 fails on qemux86-64 when qemu has a small number cores,
>> e.g. "qemu -smp 1/2/4/6".
>>
>> ERROR INFO:
>>
>> signal06?????? 0?? TINFO?? :?? loop = 23
>> signal06?????? 1?? TFAIL?? :?? signal06.c:87: Bug Reproduced!
>>
>> But if boot qemu with "-smp 16", the case has great chance to pass.
>>
>>
>> I have two questions about this case:
>>
>> 1. I don't know why multi-core will affect the case.
> Have you looked into the code? The test is trying to reproduce a race
> condition between two threads of course the number of cores does affect
> the reproducibility.
>
>> 2. On failure situation, what does break the "while loop" shown in below
>> code.
> Bug in a kernel that fails to restore fpu state.
>