On Wednesday 22 October 2008 19:25 Oren Laadan wrote: > Andrey Mirkin wrote: > > On Wednesday 22 October 2008 13:25 Louis Rilling wrote: > >> On Wed, Oct 22, 2008 at 12:49:54PM +0400, Andrey Mirkin wrote: > >>> 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. > >> > >> Do you checkpoint uninterruptible syscalls as well? If only > >> interruptible syscalls are checkpointed, I'd say that either this > >> syscall uses ERESTARTSYS or ERESTART_RESTARTBLOCK, and then signal > >> handling code already does the trick, or this syscall does not restart > >> itself when interrupted, and well, this is life, userspace just sees > >> -EINTR, which is allowed by the syscall spec. > >> Actually this is how we checkpoint/migrate tasks in interruptible > >> syscalls in Kerrighed and this works. > > > > We checkpoint only interruptible syscalls. Some syscalls do not restart > > themself, that is why after restarting a process we restart syscall to > > complete it. > > Can you please elaborate on this ? I don't recall having had issues > with that. Right now in 2.6.18 kernel we restarts in such a way pause, rt_sigtimedwait and futex syscalls. Recently futex syscall was reworked and we will not need such hooks for it. Andrey _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers