On Tuesday 16 June 2009, Pallipadi, Venkatesh wrote: > On Tue, 2009-06-16 at 14:09 -0700, Andrew Morton wrote: > > On Tue, 16 Jun 2009 22:40:39 +0200 > > > > Johannes Stezenbach <js@xxxxxxxxx> wrote: > > > On Tue, Jun 16, 2009 at 01:25:58PM -0700, Pallipadi, Venkatesh wrote: > > > > Can you try the patch below (your changes + a warnon). That should > > > > give the stack trace with successful suspend-resume. > > > > > > > > acpi-cpufreq will not directly disable interrupt and call these > > > > routines. So, it will be interesting to see how we are ending up in > > > > this state. > > > > > > Yes, I actually had the same idea and just did it ;-) > > > I also found this: > > > http://lkml.org/lkml/2007/7/17/674 > > > > > > ------------[ cut here ]------------ > > > WARNING: at kernel/up.c:18 smp_call_function_single+0x45/0x60() > > > Hardware name: 2373Y4M > > > Modules linked in: ath5k mac80211 cfg80211 uhci_hcd ehci_hcd > > > Pid: 4139, comm: bash Not tainted 2.6.30 #8 > > > Call Trace: > > > [<c011ea0d>] warn_slowpath_common+0x60/0x90 > > > [<c010d86c>] ? do_drv_read+0x0/0x31 > > > [<c011ea4a>] warn_slowpath_null+0xd/0x10 > > > [<c013acc1>] smp_call_function_single+0x45/0x60 > > > [<c010d4e5>] get_cur_val+0x62/0x6c > > > [<c010d72f>] get_cur_freq_on_cpu+0x35/0x58 > > > [<c03786e9>] cpufreq_suspend+0x76/0xd9 > > > [<c0136c3b>] ? clockevents_notify+0x1e/0x68 > > > [<c02ff570>] sysdev_suspend+0x4e/0x182 > > > [<c013fd28>] hibernation_snapshot+0x89/0x16b > > > [<c013fe99>] hibernate+0x8f/0x147 > > > [<c013ec82>] ? state_store+0x0/0xa2 > > > [<c013ecd7>] state_store+0x55/0xa2 > > > [<c013ec82>] ? state_store+0x0/0xa2 > > > [<c024dff5>] kobj_attr_store+0x1a/0x22 > > > [<c01a7164>] sysfs_write_file+0xb4/0xdf > > > [<c01a70b0>] ? sysfs_write_file+0x0/0xdf > > > [<c0170cf2>] vfs_write+0x8a/0x12c > > > [<c0170e2d>] sys_write+0x3b/0x60 > > > [<c01028f4>] sysenter_do_call+0x12/0x26 > > > ---[ end trace 1c2172bce3982a59 ]--- > > > > Right, so it's the suspend-must-disable-local-interrupts thing. Again. > > create_image()'s local_irq_disable(). > > > > It was wrong to call work_on_cpu() with lcoal interrupts disabled, and > > it's now wrong to call smp_call_function_single() with local interrupts > > disabled. It's just that smp_call_function_single() warns while > > work_on_cpu() didn't. > > > > That all explains the warning But afaik we still don't know why your > > machine actually failed. Perhaps it is a side-efect of emitting the > > warning when the console is in a weird state? > > > > So.. what to do? Possibly we could hack cpufreq to not use > > smp_call_function_single() if the call is to be done on the local CPU. > > But SMP might still be broken - if it really does want to do a cross-cpu > > call. > > We surely do not need cross CPU cal at this point as all secondary cpus > will be offline at this point. > > > Why does cpufreq need to do a cross-CPU get_cur_freq_on_cpu() call at > > suspend time _anyway_? Surely cpufreq knows the target CPU's frequency > > from its internal in-main-memory state? > > That was what I was wondering as well. Looks like this part of > cpufreq_suspend came from > > commit 42d4dc3f4e1ec1396371aac89d0dccfdd977191b > Author: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx> > Date: Fri Apr 29 07:40:12 2005 -0700 > > [PATCH] Add suspend method to cpufreq core > > In order to properly fix some issues with cpufreq vs. sleep on > PowerBooks, I had to add a suspend callback to the pmac_cpufreq > driver. > I must force a switch to full speed before sleep and I switch back > to > previous speed on resume. > > I also added a driver flag to disable the warnings in suspend/resume > since it is expected in this case to have different speed (and I > want it > to fixup the jiffies properly). > > Signed-off-by: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx> > Signed-off-by: Andrew Morton <akpm@xxxxxxxx> > Signed-off-by: Linus Torvalds <torvalds@xxxxxxxx> > > > > benh: Do you think we still need this cpufreq_driver->get() and return > error on (!cur_freq || !cpu_policy->cur) stuff? > May be we should all the checks only if CPUFREQ_PM_NO_WARN is set? In fact, we need to do this entire thing differently. The basic problem is that cpufreq_suspend() is a sysdev thing, so it will always be called with iterrupts off and *only* for CPU0. So, it looks like the majority of things we do there is just unnecessary (at least). Best, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
