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Message-ID: <tkrat.8b4396bb1aafd7a5@s5r6.in-berlin.de>
Date: Fri, 9 Jan 2009 23:28:38 +0100 (CET)
From: Stefan Richter <stefanr@...6.in-berlin.de>
To: Linus Torvalds <torvalds@...ux-foundation.org>,
Andrew Morton <akpm@...ux-foundation.org>
cc: Alan Cox <alan@...rguk.ukuu.org.uk>,
linux1394-devel@...ts.sourceforge.net,
Kay Sievers <kay.sievers@...y.org>,
linux-kernel@...r.kernel.org, Jay Fenlason <fenlason@...hat.com>,
Greg KH <gregkh@...e.de>
Subject: [git pull] FireWire fix
On 9 Jan, Greg KH wrote:
> On Fri, Jan 09, 2009 at 09:17:18PM +0000, Alan Cox wrote:
>> On Fri, 9 Jan 2009 20:49:37 +0100 (CET)
>> Stefan Richter <stefanr@...6.in-berlin.de> wrote:
>>
>> > Due to commit 2831fe6f9cc4e16c103504ee09a47a084297c0f3, "driver core:
>> > create a private portion of struct device", device_initialize() can no
>> > longer be called from atomic contexts.
>>
>> I don't see why this is neccessary or appropriate - the original commit
>> needs to be pulled and the private area allocation rethought.
>
> Ugh, I think you're right. I'll revert this (and all of the patches in
> the series that were needed to get this working properly), and redo the
> patch set, first making device_initialize() able to fail, and auditing
> all callers to make sure it's not being called in atomic context.
>
> At first glance, I think it's only firewire that is doing this in atomic
> context, so Stefan, I wouldn't mind seeing your patch go in as-is just
> to make things simpler overall.
>
> I'll go make up the patchset and send them to Linus...
Linus,
please pull from the for-linus branch at
git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6.git for-linus
to receive the following change --- as a hotfix for now, and to expand
Greg's options when he sorts device_initialize() out later.
Stefan Richter (1):
firewire: core: fix sleep in atomic context due to driver core change
drivers/firewire/fw-card.c | 13 +++++++------
drivers/firewire/fw-device.c | 23 +++++++++++++----------
2 files changed, 20 insertions(+), 16 deletions(-)
commit 6230582320b721e6cf2581d048cb688dca97f504
Author: Stefan Richter <stefanr@...6.in-berlin.de>
Date: Fri Jan 9 20:49:37 2009 +0100
firewire: core: fix sleep in atomic context due to driver core change
Due to commit 2831fe6f9cc4e16c103504ee09a47a084297c0f3, "driver core:
create a private portion of struct device", device_initialize() can no
longer be called from atomic contexts.
We now defer it until after config ROM probing. This requires changes
to the bus manager code because this may use a device before it was
probed.
Reported-by: Jay Fenlason <fenlason@...hat.com>
Signed-off-by: Stefan Richter <stefanr@...6.in-berlin.de>
diff --git a/drivers/firewire/fw-card.c b/drivers/firewire/fw-card.c
index 799f944..6bd91a1 100644
--- a/drivers/firewire/fw-card.c
+++ b/drivers/firewire/fw-card.c
@@ -209,6 +209,8 @@ fw_card_bm_work(struct work_struct *work)
unsigned long flags;
int root_id, new_root_id, irm_id, gap_count, generation, grace, rcode;
bool do_reset = false;
+ bool root_device_is_running;
+ bool root_device_is_cmc;
__be32 lock_data[2];
spin_lock_irqsave(&card->lock, flags);
@@ -224,8 +226,9 @@ fw_card_bm_work(struct work_struct *work)
generation = card->generation;
root_device = root_node->data;
- if (root_device)
- fw_device_get(root_device);
+ root_device_is_running = root_device &&
+ atomic_read(&root_device->state) == FW_DEVICE_RUNNING;
+ root_device_is_cmc = root_device && root_device->cmc;
root_id = root_node->node_id;
grace = time_after(jiffies, card->reset_jiffies + DIV_ROUND_UP(HZ, 10));
@@ -308,14 +311,14 @@ fw_card_bm_work(struct work_struct *work)
* config rom. In either case, pick another root.
*/
new_root_id = local_node->node_id;
- } else if (atomic_read(&root_device->state) != FW_DEVICE_RUNNING) {
+ } else if (!root_device_is_running) {
/*
* If we haven't probed this device yet, bail out now
* and let's try again once that's done.
*/
spin_unlock_irqrestore(&card->lock, flags);
goto out;
- } else if (root_device->cmc) {
+ } else if (root_device_is_cmc) {
/*
* FIXME: I suppose we should set the cmstr bit in the
* STATE_CLEAR register of this node, as described in
@@ -362,8 +365,6 @@ fw_card_bm_work(struct work_struct *work)
fw_core_initiate_bus_reset(card, 1);
}
out:
- if (root_device)
- fw_device_put(root_device);
fw_node_put(root_node);
fw_node_put(local_node);
out_put_card:
diff --git a/drivers/firewire/fw-device.c b/drivers/firewire/fw-device.c
index c173be3..2af5a8d 100644
--- a/drivers/firewire/fw-device.c
+++ b/drivers/firewire/fw-device.c
@@ -159,7 +159,8 @@ static void fw_device_release(struct device *dev)
/*
* Take the card lock so we don't set this to NULL while a
- * FW_NODE_UPDATED callback is being handled.
+ * FW_NODE_UPDATED callback is being handled or while the
+ * bus manager work looks at this node.
*/
spin_lock_irqsave(&card->lock, flags);
device->node->data = NULL;
@@ -695,12 +696,13 @@ static void fw_device_init(struct work_struct *work)
return;
}
- err = -ENOMEM;
+ device_initialize(&device->device);
fw_device_get(device);
down_write(&fw_device_rwsem);
- if (idr_pre_get(&fw_device_idr, GFP_KERNEL))
- err = idr_get_new(&fw_device_idr, device, &minor);
+ err = idr_pre_get(&fw_device_idr, GFP_KERNEL) ?
+ idr_get_new(&fw_device_idr, device, &minor) :
+ -ENOMEM;
up_write(&fw_device_rwsem);
if (err < 0)
@@ -911,13 +913,14 @@ void fw_node_event(struct fw_card *card, struct fw_node *node, int event)
/*
* Do minimal intialization of the device here, the
- * rest will happen in fw_device_init(). We need the
- * card and node so we can read the config rom and we
- * need to do device_initialize() now so
- * device_for_each_child() in FW_NODE_UPDATED is
- * doesn't freak out.
+ * rest will happen in fw_device_init().
+ *
+ * Attention: A lot of things, even fw_device_get(),
+ * cannot be done before fw_device_init() finished!
+ * You can basically just check device->state and
+ * schedule work until then, but only while holding
+ * card->lock.
*/
- device_initialize(&device->device);
atomic_set(&device->state, FW_DEVICE_INITIALIZING);
device->card = fw_card_get(card);
device->node = fw_node_get(node);
Thanks,
--
Stefan Richter
-=====-==--= ---= -=--=
http://arcgraph.de/sr/
--
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