On Monday, April 08, 2013 10:51:45 AM chenhc@xxxxxxxxxx wrote: > > On Sunday, April 07, 2013 08:29:32 AM Greg KH wrote: > >> On Sun, Apr 07, 2013 at 10:46:00AM +0200, Rafael J. Wysocki wrote: > >> > On Sunday, April 07, 2013 10:14:14 AM Huacai Chen wrote: > >> > > As commit 40dc166c (PM / Core: Introduce struct syscore_ops for core > >> > > subsystems PM) say, syscore_ops operations should be carried with > >> one > >> > > CPU on-line and interrupts disabled. However, after commit f96972f2d > >> > > (kernel/sys.c: call disable_nonboot_cpus() in kernel_restart()), > >> > > syscore_shutdown() is called before disable_nonboot_cpus(), so break > >> > > the rules. We have a MIPS machine with a 8259A PIC, and there is an > >> > > external timer (HPET) linked at 8259A. Since 8259A has been shutdown > >> > > too early (by syscore_shutdown()), disable_nonboot_cpus() runs > >> without > >> > > timer interrupt, so it hangs and reboot fails. This patch call > >> > > syscore_shutdown() a little later (after disable_nonboot_cpus()) to > >> > > avoid reboot failure, this is the same way as poweroff does. > >> > > > >> > > BTW, add disable_nonboot_cpus() in kernel_halt() for consistency. > >> > > > >> > > Signed-off-by: Huacai Chen <chenhc@xxxxxxxxxx> > >> > > Cc: <stable@xxxxxxxxxxxxxxx> > >> > > >> > While I agree with the changes, I'm not sure if I'm the right > >> maintainer, > >> > as this isn't really PM code. > >> > > >> > Andrew, should I take this? > >> > >> Andrew is on vacation for a few weeks, so you might need to take this > >> through your tree. > > > > OK > > > > But, it looks like we should actually disable interrupts on the remaining > > CPU after we've called disable_nonboot_cpus() so that the > > syscore_shutdown() > > assumptions are satisfied which the patch doesn't do. > > > > Chen (I apologize if that's not the right part of your full name to use > > here), > > do you think that's not necessary and if so, then for what reason? > > Reboot and poweroff are both OK after I move syscore_shutdown(), I also don't > know whether we should disable interrupts. Since you are the author of > commit 40dc166c (PM / Core: Introduce struct syscore_ops for core subsystems > PM), please tell me why syscore_shutdown() need interrupt disabled? Well, the syscore_ callbacks generally do things that may go wrong when an interrupt comes in while they are being done. At least that's what happens for the suspend/resume syscore_ callbacks, but I'm not really sure about the shutdown ones. I suppose we can leave it as is for the time being. At least I'm not aware of any problems related to that. Thanks, Rafael -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html