firewire: keep highlevel drivers attached during brief connection loss
There are situations when nodes vanish from the bus and come back
quickly thereafter:
- When certain bus-powered hubs are plugged in,
- when certain devices are plugged into 6-port hubs,
- when certain disk enclosures are switched from self-power to bus
power or vice versa and break the daisy chain during the transition,
- when the user plugs a cable out and quickly plugs it back in, e.g.
to reorder a daisy chain (works on Mac OS X if done quickly enough),
- when certain hubs temporarily malfunction during high bus traffic.
Until now, firewire-core reported affected nodes as lost to the
highlevel drivers (firewire-sbp2 and userspace drivers). We now delay
the destruction of device representations until after at least two
seconds after the last bus reset. If a "new" device is detected in this
period whose bus information block and root directory header match that
of a device which is pending for deletion, we resurrect that device and
send update calls to highlevel drivers.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
diff --git a/drivers/firewire/fw-device.c b/drivers/firewire/fw-device.c
index 2af5a8d..0925d91 100644
--- a/drivers/firewire/fw-device.c
+++ b/drivers/firewire/fw-device.c
@@ -25,6 +25,7 @@
#include <linux/device.h>
#include <linux/delay.h>
#include <linux/idr.h>
+#include <linux/jiffies.h>
#include <linux/string.h>
#include <linux/rwsem.h>
#include <linux/semaphore.h>
@@ -634,26 +635,6 @@
return device;
}
-static void fw_device_shutdown(struct work_struct *work)
-{
- struct fw_device *device =
- container_of(work, struct fw_device, work.work);
- int minor = MINOR(device->device.devt);
-
- fw_device_cdev_remove(device);
- device_for_each_child(&device->device, NULL, shutdown_unit);
- device_unregister(&device->device);
-
- down_write(&fw_device_rwsem);
- idr_remove(&fw_device_idr, minor);
- up_write(&fw_device_rwsem);
- fw_device_put(device);
-}
-
-static struct device_type fw_device_type = {
- .release = fw_device_release,
-};
-
/*
* These defines control the retry behavior for reading the config
* rom. It shouldn't be necessary to tweak these; if the device
@@ -668,11 +649,96 @@
#define MAX_RETRIES 10
#define RETRY_DELAY (3 * HZ)
#define INITIAL_DELAY (HZ / 2)
+#define SHUTDOWN_DELAY (2 * HZ)
+
+static void fw_device_shutdown(struct work_struct *work)
+{
+ struct fw_device *device =
+ container_of(work, struct fw_device, work.work);
+ int minor = MINOR(device->device.devt);
+
+ if (time_is_after_jiffies(device->card->reset_jiffies + SHUTDOWN_DELAY)) {
+ schedule_delayed_work(&device->work, SHUTDOWN_DELAY);
+ return;
+ }
+
+ if (atomic_cmpxchg(&device->state,
+ FW_DEVICE_GONE,
+ FW_DEVICE_SHUTDOWN) != FW_DEVICE_GONE)
+ return;
+
+ fw_device_cdev_remove(device);
+ device_for_each_child(&device->device, NULL, shutdown_unit);
+ device_unregister(&device->device);
+
+ down_write(&fw_device_rwsem);
+ idr_remove(&fw_device_idr, minor);
+ up_write(&fw_device_rwsem);
+
+ fw_device_put(device);
+}
+
+static struct device_type fw_device_type = {
+ .release = fw_device_release,
+};
+
+static void fw_device_update(struct work_struct *work);
+
+/*
+ * If a device was pending for deletion because its node went away but its
+ * bus info block and root directory header matches that of a newly discovered
+ * device, revive the existing fw_device.
+ * The newly allocated fw_device becomes obsolete instead.
+ */
+static int lookup_existing_device(struct device *dev, void *data)
+{
+ struct fw_device *old = fw_device(dev);
+ struct fw_device *new = data;
+ struct fw_card *card = new->card;
+ int match = 0;
+
+ down_read(&fw_device_rwsem); /* serialize config_rom access */
+ spin_lock_irq(&card->lock); /* serialize node access */
+
+ if (memcmp(old->config_rom, new->config_rom, 6 * 4) == 0 &&
+ atomic_cmpxchg(&old->state,
+ FW_DEVICE_GONE,
+ FW_DEVICE_RUNNING) == FW_DEVICE_GONE) {
+ struct fw_node *current_node = new->node;
+ struct fw_node *obsolete_node = old->node;
+
+ new->node = obsolete_node;
+ new->node->data = new;
+ old->node = current_node;
+ old->node->data = old;
+
+ old->max_speed = new->max_speed;
+ old->node_id = current_node->node_id;
+ smp_wmb(); /* update node_id before generation */
+ old->generation = card->generation;
+ old->config_rom_retries = 0;
+ fw_notify("rediscovered device %s\n", dev_name(dev));
+
+ PREPARE_DELAYED_WORK(&old->work, fw_device_update);
+ schedule_delayed_work(&old->work, 0);
+
+ if (current_node == card->root_node)
+ fw_schedule_bm_work(card, 0);
+
+ match = 1;
+ }
+
+ spin_unlock_irq(&card->lock);
+ up_read(&fw_device_rwsem);
+
+ return match;
+}
static void fw_device_init(struct work_struct *work)
{
struct fw_device *device =
container_of(work, struct fw_device, work.work);
+ struct device *revived_dev;
int minor, err;
/*
@@ -696,6 +762,15 @@
return;
}
+ revived_dev = device_find_child(device->card->device,
+ device, lookup_existing_device);
+ if (revived_dev) {
+ put_device(revived_dev);
+ fw_device_release(&device->device);
+
+ return;
+ }
+
device_initialize(&device->device);
fw_device_get(device);
@@ -734,9 +809,10 @@
* fw_node_event().
*/
if (atomic_cmpxchg(&device->state,
- FW_DEVICE_INITIALIZING,
- FW_DEVICE_RUNNING) == FW_DEVICE_SHUTDOWN) {
- fw_device_shutdown(work);
+ FW_DEVICE_INITIALIZING,
+ FW_DEVICE_RUNNING) == FW_DEVICE_GONE) {
+ PREPARE_DELAYED_WORK(&device->work, fw_device_shutdown);
+ schedule_delayed_work(&device->work, SHUTDOWN_DELAY);
} else {
if (device->config_rom_retries)
fw_notify("created device %s: GUID %08x%08x, S%d00, "
@@ -847,8 +923,8 @@
case REREAD_BIB_UNCHANGED:
if (atomic_cmpxchg(&device->state,
- FW_DEVICE_INITIALIZING,
- FW_DEVICE_RUNNING) == FW_DEVICE_SHUTDOWN)
+ FW_DEVICE_INITIALIZING,
+ FW_DEVICE_RUNNING) == FW_DEVICE_GONE)
goto gone;
fw_device_update(work);
@@ -879,8 +955,8 @@
create_units(device);
if (atomic_cmpxchg(&device->state,
- FW_DEVICE_INITIALIZING,
- FW_DEVICE_RUNNING) == FW_DEVICE_SHUTDOWN)
+ FW_DEVICE_INITIALIZING,
+ FW_DEVICE_RUNNING) == FW_DEVICE_GONE)
goto gone;
fw_notify("refreshed device %s\n", dev_name(&device->device));
@@ -890,8 +966,9 @@
give_up:
fw_notify("giving up on refresh of device %s\n", dev_name(&device->device));
gone:
- atomic_set(&device->state, FW_DEVICE_SHUTDOWN);
- fw_device_shutdown(work);
+ atomic_set(&device->state, FW_DEVICE_GONE);
+ PREPARE_DELAYED_WORK(&device->work, fw_device_shutdown);
+ schedule_delayed_work(&device->work, SHUTDOWN_DELAY);
out:
if (node_id == card->root_node->node_id)
fw_schedule_bm_work(card, 0);
@@ -995,9 +1072,9 @@
*/
device = node->data;
if (atomic_xchg(&device->state,
- FW_DEVICE_SHUTDOWN) == FW_DEVICE_RUNNING) {
+ FW_DEVICE_GONE) == FW_DEVICE_RUNNING) {
PREPARE_DELAYED_WORK(&device->work, fw_device_shutdown);
- schedule_delayed_work(&device->work, 0);
+ schedule_delayed_work(&device->work, SHUTDOWN_DELAY);
}
break;
}