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Date: Fri, 9 Jan 2009 20:49:37 +0100 (CET)
From: Stefan Richter <stefanr@...6.in-berlin.de>
To: linux1394-devel@...ts.sourceforge.net
cc: Kay Sievers <kay.sievers@...y.org>, linux-kernel@...r.kernel.org,
Jay Fenlason <fenlason@...hat.com>,
Greg Kroah-Hartman <gregkh@...e.de>
Subject: [PATCH post 2.6.28] 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>
---
This still needs a lot of testing since I may have easily missed
something. Even if it works, it complicates firewire-core's lifetime
rules.
Better would be to fix driver core to not sleep in device_initialize
(and besides, never fail in void device_initialize).
drivers/firewire/fw-card.c | 13 +++++++------
drivers/firewire/fw-device.c | 23 +++++++++++++----------
2 files changed, 20 insertions(+), 16 deletions(-)
Index: linux/drivers/firewire/fw-device.c
===================================================================
--- linux.orig/drivers/firewire/fw-device.c
+++ linux/drivers/firewire/fw-device.c
@@ -160,7 +160,8 @@ static void fw_device_release(struct 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;
@@ -693,12 +694,13 @@ static void fw_device_init(struct work_s
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)
@@ -909,13 +911,14 @@ void fw_node_event(struct fw_card *card,
/*
* 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);
Index: linux/drivers/firewire/fw-card.c
===================================================================
--- linux.orig/drivers/firewire/fw-card.c
+++ linux/drivers/firewire/fw-card.c
@@ -203,6 +203,8 @@ static void fw_card_bm_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);
@@ -218,8 +220,9 @@ static void fw_card_bm_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));
@@ -302,14 +305,14 @@ static void fw_card_bm_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
@@ -356,8 +359,6 @@ static void fw_card_bm_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:
--
Stefan Richter
-=====-==--= ---= -=--=
http://arcgraph.de/sr/
--
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