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SubjectRe: [Devel] Re: [PATCH 08/10] Introduce functions to restart a process
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On Monday 20 October 2008 13:23 Cedric Le Goater wrote:
> Hello Andrey !
>
> > diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
> > index 109792b..a4848a3 100644
> > --- a/arch/x86/kernel/entry_32.S
> > +++ b/arch/x86/kernel/entry_32.S
> > @@ -225,6 +225,7 @@ ENTRY(ret_from_fork)
> > GET_THREAD_INFO(%ebp)
> > popl %eax
> > CFI_ADJUST_CFA_OFFSET -4
> > +ret_from_fork_tail:
> > pushl $0x0202 # Reset kernel eflags
> > CFI_ADJUST_CFA_OFFSET 4
> > popfl
> > @@ -233,6 +234,26 @@ ENTRY(ret_from_fork)
> > CFI_ENDPROC
> > END(ret_from_fork)
> >
> > +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.

Andrey


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