Re: [Devel] Re: [PATCH 08/10] Introduce functions to restart a process

From: Cedric Le Goater
Date: Wed Oct 22 2008 - 08:48:27 EST


>>> +ENTRY(i386_ret_from_resume)
>>> + CFI_STARTPROC
>>> + pushl %eax
>>> + CFI_ADJUST_CFA_OFFSET 4
>>> + call schedule_tail
>>> + GET_THREAD_INFO(%ebp)
>>> + popl %eax
>>> + CFI_ADJUST_CFA_OFFSET -4
>>> + movl (%esp), %eax
>>> + testl %eax, %eax
>>> + jz 1f
>>> + pushl %esp
>>> + call *%eax
>>> + addl $4, %esp
>>> +1:
>>> + addl $256, %esp
>>> + jmp ret_from_fork_tail
>>> + CFI_ENDPROC
>>> +END(i386_ret_from_resume)
>> Could you explain why you need to do this
>>
>> call *%eax
>>
>> is it related to the freezer code ?
>
> It is not related to the freezer code actually.
> That is needed to restart syscalls. Right now I don't have a code in my
> patchset which restarts a syscall, but later I plan to add it.
> In OpenVZ checkpointing we restart syscalls if process was caught in syscall
> during checkpointing.

ok. I get it now. why 256 bytes of extra stack ? I'm sure it's not random.

Thanks,

C.
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