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

[Cedric Le Goater]

>>> +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.