Serge E. Hallyn wrote: > (this is on top of the patch > 's390: actually restart syscalls after sys_restart' > which I sent last Thursday) > > We use TIF_RESTARTBLOCK in do_signal() to tell sys_checkpoint() > to mark the thread as needing a sysc_do_restart to restart an > interrupted syscall after sys_restart(). > > However, as Oren pointed out, if the task receives a signal > after sys_restart() but before returning to userspace, and > enters do_signal, then conditions will not be met to set > TIF_RESTARTBLOCK. So if the restarted task freezes here and is > checkpointed, then the resulting checkpoint image will not restart > the interrupted syscall. > > So, set TIF_RESTARTBLOCK in sys_restart() if TIF_RESTARTBLOCK was set > at checkpoint. Clear TIF_RESTARTBLOCK in ssyc_do_restart, so that
All I see in this patch (below) is the "clear" part. I don't see the "set" part. Also, I'm still not convinced that this fixes all 3 issues that I mentioned in the other thread. Oren. > if we do not go to do_signal right after sys_restart() we don't > mistakenly keep running with that flag. > > To test this, add a dummy handler for SIGUSR1 to cr_tests/sleep/sleeptest.c, > open two terminals, and do: > > Terminal 1: Terminal : > mount -t cgroup -o freezer freezer /cgroup > mkdir /cgroup/1 /cgroup/2 > echo $$ > /cgroup/1/tasks > ./sleeptest > > echo FROZEN > /cgroup/1/freezer.state > checkpoint `pidof sleeptest` > > /tmp/out > thaw > > restart -F /cgroup/2 < /tmp/out > > kill -USR1 `pidof sleeptest`; > echo THAWED > /cgroup/2/freezer.state > ; > sleep 0.3; > echo FROZEN > /cgroup/2/freezer.state; > checkpoint `pidof sleeptest` > > /tmp/out2; > echo THAWED > /cgroup/2/freezer.state > > restart < /tmp/out2 > > Without this patch, the final restart will immediately exit. With > this patch, it will restart the sleep. > > Signed-off-by: Serge E. Hallyn <[email protected]> > --- > arch/s390/kernel/entry64.S | 2 ++ > 1 files changed, 2 insertions(+), 0 deletions(-) > > diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S > index 9aff1d4..798ea9c 100644 > --- a/arch/s390/kernel/entry64.S > +++ b/arch/s390/kernel/entry64.S > @@ -58,6 +58,7 @@ _TIF_WORK_INT = (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | > _TIF_NEED_RESCHED | \ > _TIF_MCCK_PENDING) > _TIF_SYSCALL = (_TIF_SYSCALL_TRACE>>8 | _TIF_SYSCALL_AUDIT>>8 | \ > _TIF_SECCOMP>>8 | _TIF_SYSCALL_TRACEPOINT>>8) > +CLR_TIF_RESTARTBLOCK = (255 - (_TIF_RESTARTBLOCK>>16)) > > #define BASED(name) name-system_call(%r13) > > @@ -338,6 +339,7 @@ sysc_mcck_pending: > # > sysc_sigpending: > ni __TI_flags+7(%r9),255-_TIF_SINGLE_STEP # clear TIF_SINGLE_STEP > + ni __TI_flags+6(%r9),CLR_TIF_RESTARTBLOCK # clear TIF_RESTARTBLOCK > la %r2,SP_PTREGS(%r15) # load pt_regs > brasl %r14,do_signal # call do_signal > tm __TI_flags+7(%r9),_TIF_RESTART_SVC _______________________________________________ Containers mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/containers _______________________________________________ Devel mailing list [email protected] https://openvz.org/mailman/listinfo/devel
