From: "Rafael J. Wysocki" <rjw@sisk.pl>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Pierre Ossman <drzeus-mmc@drzeus.cx>,
Zdenek Kabelac <zdenek.kabelac@gmail.com>,
Kernel development list <linux-kernel@vger.kernel.org>
Subject: Re: [Bug 10030] Suspend doesn't work when SD card is inserted
Date: Thu, 21 Feb 2008 23:47:24 +0100 [thread overview]
Message-ID: <200802212347.25150.rjw@sisk.pl> (raw)
In-Reply-To: <Pine.LNX.4.44L0.0802211243240.5473-100000@iolanthe.rowland.org>
On Thursday, 21 of February 2008, Alan Stern wrote:
> On Thu, 21 Feb 2008, Rafael J. Wysocki wrote:
>
> > > > --- linux-2.6.orig/drivers/base/core.c
> > > > +++ linux-2.6/drivers/base/core.c
> > > > @@ -929,6 +929,11 @@ void device_del(struct device *dev)
> > > > struct device *parent = dev->parent;
> > > > struct class_interface *class_intf;
> > > >
> > > > + if (in_suspend_context()) {
> > > > + get_device(dev);
> > >
> > > Where is this get_device() undone? Shouldn't there be an extra
> > > put_device() added to unregister_dropped_devices()?
> >
> > No, I don't think so, because unregister_dropped_devices() calls
> > device_unregister() that does the put_device() eventually.
>
> Ah, yes.
>
> > If we are called by device_unregister(), the get_device() is needed to balance
> > the put_device() that will be called by device_unregister() after we return.
> >
> > OTOH, if we are called directly, then we need to balance the put_device()
> > that will be done by device_unregister() called from
> > unregister_dropped_devices().
> >
> > I hope I didn't miss anything.
>
> Okay, that sounds right.
>
> > > > + device_pm_schedule_removal(dev);
> > > > + return;
> > > > + }
> > > > device_pm_remove(dev);
> > > > if (parent)
> > > > klist_del(&dev->knode_parent);
> > >
> > > And now the change to device_destroy() isn't needed at all.
> >
> > No, it's not. Didn't I remove it? I thought I did.
>
> Oh yes, you did.
>
> I see a possible problem in device_resume(). My copy isn't fully
> up-to-date, but it looks like you call unregister_dropped_devices()
> before doing the up_write(&pm_sleep_rwsem). Won't this cause
> warnings in device_del() about a suspicious caller?
No, it won't, because the devices' semaphores are unlocked by
unregister_dropped_devices() before calling device_unregister().
BTW, below is a simplified version of the patch, without the mutex protecting
suspending_task. I'd like to push it upstream if it looks good.
Please also have a look at http://bugzilla.kernel.org/show_bug.cgi?id=10030.
There seems to be another issue related to us holding devices' semaphores.
Namely, it looks like, when the user removes the card, a concurrent thread
(from a workqueue) calls device_del() and blocks on the dev->sem held by
us and then something else deadlocks with this thread. I'll be looking into
this tomorrow.
Thanks,
Rafael
---
drivers/base/core.c | 5 +++++
drivers/base/power/main.c | 9 +++++++++
drivers/base/power/power.h | 5 +++++
3 files changed, 19 insertions(+)
Index: linux-2.6/drivers/base/power/main.c
===================================================================
--- linux-2.6.orig/drivers/base/power/main.c
+++ linux-2.6/drivers/base/power/main.c
@@ -59,6 +59,13 @@ static DECLARE_RWSEM(pm_sleep_rwsem);
int (*platform_enable_wakeup)(struct device *dev, int is_on);
+static struct task_struct *suspending_task;
+
+bool in_suspend_context(void)
+{
+ return (suspending_task == current);
+}
+
/**
* device_pm_add - add a device to the list of active devices
* @dev: Device to be added to the list
@@ -272,6 +279,7 @@ static void dpm_resume(void)
mutex_lock(&dpm_list_mtx);
}
mutex_unlock(&dpm_list_mtx);
+ suspending_task = NULL;
}
/**
@@ -460,6 +468,7 @@ static int dpm_suspend(pm_message_t stat
{
int error = 0;
+ suspending_task = current;
mutex_lock(&dpm_list_mtx);
while (!list_empty(&dpm_locked)) {
struct list_head *entry = dpm_locked.prev;
Index: linux-2.6/drivers/base/core.c
===================================================================
--- linux-2.6.orig/drivers/base/core.c
+++ linux-2.6/drivers/base/core.c
@@ -929,6 +929,11 @@ void device_del(struct device *dev)
struct device *parent = dev->parent;
struct class_interface *class_intf;
+ if (in_suspend_context()) {
+ get_device(dev);
+ device_pm_schedule_removal(dev);
+ return;
+ }
device_pm_remove(dev);
if (parent)
klist_del(&dev->knode_parent);
Index: linux-2.6/drivers/base/power/power.h
===================================================================
--- linux-2.6.orig/drivers/base/power/power.h
+++ linux-2.6/drivers/base/power/power.h
@@ -11,6 +11,7 @@ static inline struct device *to_device(s
return container_of(entry, struct device, power.entry);
}
+extern bool in_suspend_context(void);
extern void device_pm_add(struct device *);
extern void device_pm_remove(struct device *);
extern int pm_sleep_lock(void);
@@ -18,6 +19,10 @@ extern void pm_sleep_unlock(void);
#else /* CONFIG_PM_SLEEP */
+static inline bool in_suspend_context(void)
+{
+ return false;
+}
static inline void device_pm_add(struct device *dev)
{
next prev parent reply other threads:[~2008-02-21 22:49 UTC|newest]
Thread overview: 92+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20080219232338.E9A24108068@picon.linux-foundation.org>
2008-02-20 16:42 ` [Bug 10030] Suspend doesn't work when SD card is inserted Alan Stern
2008-02-20 17:30 ` Pierre Ossman
2008-02-20 19:26 ` Alan Stern
2008-02-20 20:51 ` Pierre Ossman
2008-02-20 20:58 ` Rafael J. Wysocki
2008-02-20 21:06 ` Alan Stern
2008-02-20 22:15 ` Rafael J. Wysocki
2008-02-20 22:24 ` Alan Stern
2008-02-20 22:41 ` Rafael J. Wysocki
2008-02-21 0:02 ` Rafael J. Wysocki
2008-02-21 16:27 ` Alan Stern
2008-02-21 16:38 ` Rafael J. Wysocki
2008-02-21 17:48 ` Alan Stern
2008-02-21 22:47 ` Rafael J. Wysocki [this message]
2008-02-21 23:05 ` Alan Stern
2008-02-23 1:30 ` Rafael J. Wysocki
2008-02-23 4:39 ` Alan Stern
2008-02-23 20:16 ` Rafael J. Wysocki
2008-02-23 23:29 ` Alan Stern
2008-02-24 0:19 ` Rafael J. Wysocki
2008-02-24 3:25 ` Alan Stern
2008-02-24 4:26 ` [linux-pm] " Alan Stern
2008-02-24 14:00 ` Rafael J. Wysocki
2008-02-24 15:33 ` Bugs in MMC [was: [Bug 10030] Suspend doesn't work when SD card is inserted] Alan Stern
2008-02-25 17:41 ` Pierre Ossman
2008-02-25 17:58 ` Alan Stern
2008-02-25 18:31 ` Pierre Ossman
2008-02-25 20:00 ` Alan Stern
2008-03-01 14:11 ` Pierre Ossman
2008-03-01 14:36 ` Alan Stern
2008-03-01 14:47 ` Pierre Ossman
2008-02-25 22:51 ` Felipe Balbi
2008-03-03 21:59 ` David Brownell
2008-03-04 6:03 ` Pierre Ossman
2008-03-04 9:44 ` David Brownell
2008-03-04 9:58 ` Pierre Ossman
2008-03-06 21:23 ` David Brownell
2008-03-04 17:53 ` Alan Stern
2008-03-04 18:53 ` David Brownell
2008-03-04 19:51 ` Alan Stern
2008-03-04 20:30 ` David Brownell
2008-03-04 21:00 ` Alan Stern
2008-03-06 15:55 ` Pavel Machek
2008-03-06 20:33 ` Alan Stern
2008-03-06 20:53 ` Zdenek Kabelac
2008-03-06 21:31 ` Rafael J. Wysocki
2008-03-04 17:50 ` Alan Stern
2008-02-24 13:33 ` [Bug 10030] Suspend doesn't work when SD card is inserted Rafael J. Wysocki
2008-02-24 20:25 ` Rafael J. Wysocki
2008-02-24 20:45 ` Alan Stern
2008-02-24 20:56 ` Rafael J. Wysocki
2008-02-24 21:11 ` Alan Stern
2008-02-24 22:18 ` Rafael J. Wysocki
2008-02-24 13:51 ` Rafael J. Wysocki
2008-02-24 19:27 ` Alan Stern
2008-02-24 19:42 ` Zdenek Kabelac
2008-02-24 20:09 ` Rafael J. Wysocki
2008-02-24 18:21 ` Pavel Machek
2008-02-24 19:03 ` Alan Stern
2008-02-24 20:11 ` Pavel Machek
2008-02-24 20:33 ` Alan Stern
2008-02-24 21:42 ` Pavel Machek
2008-02-24 22:21 ` Rafael J. Wysocki
2008-02-25 2:21 ` Alan Stern
2008-02-25 11:41 ` Rafael J. Wysocki
[not found] ` <c4e36d110802250402q7312a488idf752e07db7504e8@mail.gmail.com>
2008-02-25 12:31 ` Rafael J. Wysocki
2008-02-25 2:19 ` Alan Stern
2008-02-25 9:03 ` using long instead of atomic_t when only set/read is required (was Re: [Bug 10030] Suspend doesn't work when SD card is inserted) Pavel Machek
2008-02-25 14:46 ` Alan Stern
2008-03-03 12:08 ` [patch] Re: using long instead of atomic_t when only set/read is required Pavel Machek
2008-03-03 15:42 ` Alan Stern
2008-03-03 15:53 ` Alan Cox
2008-03-03 17:11 ` Alan Stern
2008-03-03 17:26 ` Linus Torvalds
2008-03-03 17:44 ` Pavel Machek
2008-03-03 19:27 ` Alan Stern
2008-03-06 15:58 ` Mark Lord
2008-03-06 16:11 ` Linus Torvalds
2008-03-06 16:27 ` Mark Lord
2008-03-03 17:16 ` Nick Piggin
2008-03-03 17:31 ` Paul E. McKenney
2008-03-03 17:33 ` Alan Cox
2008-03-03 17:22 ` Paul E. McKenney
2008-03-03 15:48 ` Alan Cox
2008-03-03 17:24 ` Pavel Machek
2008-03-03 20:27 ` Rafael J. Wysocki
2008-03-03 21:12 ` Paul E. McKenney
2008-03-03 22:23 ` Linus Torvalds
2008-03-04 23:32 ` Peter Hartley
2008-03-04 23:54 ` Rafael J. Wysocki
2008-03-05 0:26 ` Paul E. McKenney
2008-02-25 11:40 ` [Bug 10030] Suspend doesn't work when SD card is inserted Rafael J. Wysocki
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=200802212347.25150.rjw@sisk.pl \
--to=rjw@sisk.pl \
--cc=drzeus-mmc@drzeus.cx \
--cc=linux-kernel@vger.kernel.org \
--cc=stern@rowland.harvard.edu \
--cc=zdenek.kabelac@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).