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firewire: core: update fw_device outside of device_find_child()

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When detecting updates of bus topology, the data of fw_device is newly
allocated and caches the content of configuration ROM from the
corresponding node. Then, the tree of device is sought to find the
previous data of fw_device corresponding to the node. If found, the
previous data is updated and reused and the data of fw_device newly
allocated is going to be released.

The above procedure is done in the call of device_find_child(), however it
is a bit abusing against the intention of the helper function, since it is
preferable to find only without updating.

This commit splits the update outside of the call.

Cc: Zijun Hu <zijun_hu@icloud.com>
Link: https://lore.kernel.org/r/20240820132132.28839-1-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
This commit is contained in:
Takashi Sakamoto 2024-08-20 22:21:32 +09:00
parent 52f9fcbc7b
commit e2c87f4841
1 changed files with 59 additions and 57 deletions
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116
drivers/firewire/core-device.c
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@ -928,56 +928,6 @@ static void fw_device_update(struct work_struct *work)
device_for_each_child(&device->device, NULL, update_unit);
}
/*
* 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;
if (!is_fw_device(dev))
return 0;
guard(rwsem_read)(&fw_device_rwsem); // serialize config_rom access
guard(spinlock_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_notice(card, "rediscovered device %s\n", dev_name(dev));
old->workfn = fw_device_update;
fw_schedule_device_work(old, 0);
if (current_node == card->root_node)
fw_schedule_bm_work(card, 0);
match = 1;
}
return match;
}
enum { BC_UNKNOWN = 0, BC_UNIMPLEMENTED, BC_IMPLEMENTED, };
static void set_broadcast_channel(struct fw_device *device, int generation)
@ -1038,12 +988,24 @@ int fw_device_set_broadcast_channel(struct device *dev, void *gen)
return 0;
}
static int compare_configuration_rom(struct device *dev, void *data)
{
const struct fw_device *old = fw_device(dev);
const u32 *config_rom = data;
if (!is_fw_device(dev))
return 0;
// Compare the bus information block and root_length/root_crc.
return !memcmp(old->config_rom, config_rom, 6 * 4);
}
static void fw_device_init(struct work_struct *work)
{
struct fw_device *device =
container_of(work, struct fw_device, work.work);
struct fw_card *card = device->card;
struct device *revived_dev;
struct device *found;
u32 minor;
int ret;
@ -1071,13 +1033,53 @@ static void fw_device_init(struct work_struct *work)
return;
}
revived_dev = device_find_child(card->device,
device, lookup_existing_device);
if (revived_dev) {
put_device(revived_dev);
fw_device_release(&device->device);
// 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.
//
// serialize config_rom access.
scoped_guard(rwsem_read, &fw_device_rwsem) {
found = device_find_child(card->device, (void *)device->config_rom,
compare_configuration_rom);
}
if (found) {
struct fw_device *reused = fw_device(found);
return;
if (atomic_cmpxchg(&reused->state,
FW_DEVICE_GONE,
FW_DEVICE_RUNNING) == FW_DEVICE_GONE) {
// serialize node access
scoped_guard(spinlock_irq, &card->lock) {
struct fw_node *current_node = device->node;
struct fw_node *obsolete_node = reused->node;
device->node = obsolete_node;
device->node->data = device;
reused->node = current_node;
reused->node->data = reused;
reused->max_speed = device->max_speed;
reused->node_id = current_node->node_id;
smp_wmb(); /* update node_id before generation */
reused->generation = card->generation;
reused->config_rom_retries = 0;
fw_notice(card, "rediscovered device %s\n",
dev_name(found));
reused->workfn = fw_device_update;
fw_schedule_device_work(reused, 0);
if (current_node == card->root_node)
fw_schedule_bm_work(card, 0);
}
put_device(found);
fw_device_release(&device->device);
return;
}
put_device(found);
}
device_initialize(&device->device);