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Message-ID: <20090119164440.GA20754@elte.hu>
Date:	Mon, 19 Jan 2009 17:44:40 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Dmitry Adamushko <dmitry.adamushko@...il.com>
Cc:	Zdenek Kabelac <zdenek.kabelac@...il.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Maciej Rutecki <maciej.rutecki@...il.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Henrique de Moraes Holschuh <hmh@....eng.br>,
	dbrownell@...rs.sourceforge.net
Subject: Re: 2.6.29-rc1 does not resume on Lenove T61


* Dmitry Adamushko <dmitry.adamushko@...il.com> wrote:

> 2009/1/19 Ingo Molnar <mingo@...e.hu>:
> >
> > * Dmitry Adamushko <dmitry.adamushko@...il.com> wrote:
> >
> >> 2009/1/19 Zdenek Kabelac <zdenek.kabelac@...il.com>:
> >> > 2009/1/13 Zdenek Kabelac <zdenek.kabelac@...il.com>:
> >> >> 2009/1/13 Zdenek Kabelac <zdenek.kabelac@...il.com>:
> >> >>> 2009/1/12 Rafael J. Wysocki <rjw@...k.pl>:
> >> >>>> On Monday 12 January 2009, Zdenek Kabelac wrote:
> >> >>>
> >> >>>> Sure, good idea.  I've been running with this reverted recently.
> >> >>>>
> >> >>>>> PS: I'll do the above 'echo' trace later (being busy right now).
> >> >>>>
> >> >>>> That shouldn't be necessary if you can suspend-resume with
> >> >>>> 7503bfbae89eba07b46441a5d1594647f6b8ab7d reverted and the USB controller
> >> >>>> modules unloaded.
> >> >>>>
> >> >>>> Instead, with 7503bfbae89eba07b46441a5d1594647f6b8ab7d reverted, please write
> >> >>>> 'disabled' to the /sys/devices/.../power/wakeup files of all USB controllers
> >> >>>> and see if suspend-resume works in this configuration.
> >> >>>>
> >> >>>
> >> >>> Hi
> >> >>>
> >> >>> So I've check some   find /sys/device | grep usb | grep power/wakeup
> >> >>> and there was no difference.
> >> >>> I've updated to latest git to be in sync
> >> >>> (e0b325d310a6b11f1538413fd557d2eb98f2fae5)
> >> >>> I'm still keeping reverted commit: 6fd9086a518d4f14213a32fe6c9ac17fabebbc1e.
> >> >>>
> >> >>> And I've figured out - the only  'modprobe -r ehci_hcd' is enough to
> >> >>> keep my suspend/resume sequence working. (Though I would have say,
> >> >>> that now it takes fairly noticable time to get keyboard and synaptics
> >> >>> usable - but it might be connected with my move to evdev and hal... :)
> >> >>> )
> >> >>>
> >> >>> So I'm adding cc: to David - maybe he has some suspected patches for
> >> >>> ehci_hcd ? (as doing a bisect in such a broken merge window is going
> >> >>> to give me probably a lot of unsable kernels nowdays....)
> >> >>>
> >> >>
> >> >> And I've forget to append trace from supend /resume with INFO trace:
> >> >> (which might be a part of problem??)
> >> >
> >> > Hi
> >> >
> >> >
> >> > Just an update for  2.6.29-rc2 (f3b8436ad9a8ad36b3c9fa1fe030c7f38e5d3d0b)
> >> >
> >> > With this kernel I still have to keep reverted patch commit:
> >> > 6fd9086a518d4f14213a32fe6c9ac17fabebbc1e.
> >> > (otherwise I see the auto-wake-up immediately after suspend)
> >> >
> >> > I also keep module ehci_hcd away from my kernel - so the
> >> > suspend-resume seems to be working.
> >> >
> >> > I've checked the ideas from thread: 2.6.29-rc1: [SOLVED] thinkpad
> >> > problems during resume
> >> > http://lkml.org/lkml/2009/1/17/181  and they seems to produce some
> >> > ugly Ooops with my configuration.
> >> > so for now I stay with my revert/ehci fix.
> >> >
> >> > Also I still get the INFO trace:
> >> > processor ACPI_CPU:01: legacy suspend
> >> > processor ACPI_CPU:00: legacy suspend
> >> > button LNXPWRBN:00: legacy suspend
> >> > acpi LNXSYSTM:00: legacy suspend
> >> > ACPI: Preparing to enter system sleep state S3
> >> > Disabling non-boot CPUs ...
> >> >
> >> > =======================================================
> >> > [ INFO: possible circular locking dependency detected ]
> >> > 2.6.29-rc2 #14
> >> > -------------------------------------------------------
> >> > pm-suspend/2873 is trying to acquire lock:
> >> >  (&per_cpu(cpu_policy_rwsem, cpu)){----}, at: [<ffffffff8049a27b>]
> >> > lock_policy_rwsem_write+0x4b/0x90
> >> >
> >> > but task is already holding lock:
> >> >  (&cpu_hotplug.lock){--..}, at: [<ffffffff80246832>] cpu_hotplug_begin+0x22/0x60
> >> >
> >> > which lock already depends on the new lock.
> >> >
> >> >
> >> > the existing dependency chain (in reverse order) is:
> >> >
> >> > -> #1 (&cpu_hotplug.lock){--..}:
> >> >       [<ffffffff80270ce6>] __lock_acquire+0x1416/0x1db0
> >> >       [<ffffffff80271711>] lock_acquire+0x91/0xc0
> >> >       [<ffffffff8053d99c>] mutex_lock_nested+0xec/0x360
> >> >       [<ffffffff80246a4a>] get_online_cpus+0x3a/0x50
> >> >       [<ffffffff802594b7>] work_on_cpu+0x67/0xb0
> >> >       [<ffffffff8021e85e>] get_measured_perf+0x1e/0xb0
> >>
> >>
> >> Ingo,
> >>
> >>
> >> it looks like e39ad415ac15116df213dfa2aa2a4f1b0857af9c should have
> >> been reverted together with 7503bfbae89eba07b46441a5d1594647f6b8ab7d.
> >>
> >> In general, perhaps all "set_cpus_allowed_ptr() -> work_on_cpu()"
> >> conversions - if they involve any cpu-hotplug callback paths - may
> >> lead to similar reports (and possible lockups).
> >
> > Guys, could you please try the patch below? It improves work_on_cpu() to
> > not be dependent on the kevent workqueue.
> 
> I guess, the following patch should also be applied (since
> get_online_cpus() is a culprit here):
> 
> [PATCH 1/3] work_on_cpu: dont try to get_online_cpus() in work_on_cpu
> 
> the patch is available here:
> 
> http://lkml.indiana.edu/hypermail/linux/kernel/0901.2/00375.html

yeah - also attached below.

	Ingo

>From 68564a46976017496c2227660930d81240f82355 Mon Sep 17 00:00:00 2001
From: Rusty Russell <rusty@...tcorp.com.au>
Date: Fri, 16 Jan 2009 15:31:15 -0800
Subject: [PATCH] work_on_cpu: don't try to get_online_cpus() in work_on_cpu.

Impact: remove potential circular lock dependency with cpu hotplug lock

This has caused more problems than it solved, with a pile of cpu
hotplug locking issues.

Followup patches will get_online_cpus() in callers that need it, but
if they don't do it they're no worse than before when they were using
set_cpus_allowed without locking.

Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
Signed-off-by: Mike Travis <travis@....com>
---
 kernel/workqueue.c |   14 ++++----------
 1 files changed, 4 insertions(+), 10 deletions(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 2f44583..a35afdb 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -991,8 +991,8 @@ static void do_work_for_cpu(struct work_struct *w)
  * @fn: the function to run
  * @arg: the function arg
  *
- * This will return -EINVAL in the cpu is not online, or the return value
- * of @fn otherwise.
+ * This will return the value @fn returns.
+ * It is up to the caller to ensure that the cpu doesn't go offline.
  */
 long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg)
 {
@@ -1001,14 +1001,8 @@ long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg)
 	INIT_WORK(&wfc.work, do_work_for_cpu);
 	wfc.fn = fn;
 	wfc.arg = arg;
-	get_online_cpus();
-	if (unlikely(!cpu_online(cpu)))
-		wfc.ret = -EINVAL;
-	else {
-		schedule_work_on(cpu, &wfc.work);
-		flush_work(&wfc.work);
-	}
-	put_online_cpus();
+	schedule_work_on(cpu, &wfc.work);
+	flush_work(&wfc.work);
 
 	return wfc.ret;
 }

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