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firewire: core: code refactoring to split contention procedure for bus manager

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The precedure to contend for bus manager has much code. It is better to
split it into a helper function.

This commit refactors in the point.

Link: https://lore.kernel.org/r/20250918235448.129705-5-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
This commit is contained in:
Takashi Sakamoto
2025-09-19 08:54:46 +09:00
parent e31b990caf
commit 4ff62194d3
1 changed files with 127 additions and 96 deletions
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223
drivers/firewire/core-card.c
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@@ -279,6 +279,102 @@ void fw_schedule_bm_work(struct fw_card *card, unsigned long delay)
fw_card_put(card);
}
enum bm_contention_outcome {
// The bus management contention window is not expired.
BM_CONTENTION_OUTCOME_WITHIN_WINDOW = 0,
// The IRM node has link off.
BM_CONTENTION_OUTCOME_IRM_HAS_LINK_OFF,
// The IRM node complies IEEE 1394:1994 only.
BM_CONTENTION_OUTCOME_IRM_COMPLIES_1394_1995_ONLY,
// Another bus reset, BM work has been rescheduled.
BM_CONTENTION_OUTCOME_AT_NEW_GENERATION,
// We have been unable to send the lock request to IRM node due to some local problem.
BM_CONTENTION_OUTCOME_LOCAL_PROBLEM_AT_TRANSACTION,
// The lock request failed, maybe the IRM isn't really IRM capable after all.
BM_CONTENTION_OUTCOME_IRM_IS_NOT_CAPABLE_FOR_IRM,
// Somebody else is BM.
BM_CONTENTION_OUTCOME_IRM_HOLDS_ANOTHER_NODE_AS_BM,
// The local node succeeds after contending for bus manager.
BM_CONTENTION_OUTCOME_IRM_HOLDS_LOCAL_NODE_AS_BM,
};
static enum bm_contention_outcome contend_for_bm(struct fw_card *card)
{
int generation = card->generation;
int local_id = card->local_node->node_id;
__be32 data[2] = {
cpu_to_be32(BUS_MANAGER_ID_NOT_REGISTERED),
cpu_to_be32(local_id),
};
bool grace = time_is_before_jiffies64(card->reset_jiffies + msecs_to_jiffies(125));
bool irm_is_1394_1995_only = false;
bool keep_this_irm = false;
struct fw_node *irm_node;
struct fw_device *irm_device;
int rcode;
if (!grace) {
if (!is_next_generation(generation, card->bm_generation) || card->bm_abdicate)
return BM_CONTENTION_OUTCOME_WITHIN_WINDOW;
}
irm_node = card->irm_node;
if (!irm_node->link_on) {
fw_notice(card, "IRM has link off, making local node (%02x) root\n", local_id);
return BM_CONTENTION_OUTCOME_IRM_HAS_LINK_OFF;
}
irm_device = fw_node_get_device(irm_node);
if (irm_device && irm_device->config_rom) {
irm_is_1394_1995_only = (irm_device->config_rom[2] & 0x000000f0) == 0;
// Canon MV5i works unreliably if it is not root node.
keep_this_irm = irm_device->config_rom[3] >> 8 == CANON_OUI;
}
if (irm_is_1394_1995_only && !keep_this_irm) {
fw_notice(card, "IRM is not 1394a compliant, making local node (%02x) root\n",
local_id);
return BM_CONTENTION_OUTCOME_IRM_COMPLIES_1394_1995_ONLY;
}
rcode = fw_run_transaction(card, TCODE_LOCK_COMPARE_SWAP, irm_node->node_id, generation,
SCODE_100, CSR_REGISTER_BASE + CSR_BUS_MANAGER_ID, data,
sizeof(data));
switch (rcode) {
case RCODE_GENERATION:
return BM_CONTENTION_OUTCOME_AT_NEW_GENERATION;
case RCODE_SEND_ERROR:
return BM_CONTENTION_OUTCOME_LOCAL_PROBLEM_AT_TRANSACTION;
case RCODE_COMPLETE:
{
int bm_id = be32_to_cpu(data[0]);
// Used by cdev layer for "struct fw_cdev_event_bus_reset".
scoped_guard(spinlock, &card->lock) {
if (bm_id != BUS_MANAGER_ID_NOT_REGISTERED)
card->bm_node_id = 0xffc0 & bm_id;
else
card->bm_node_id = local_id;
}
if (bm_id != BUS_MANAGER_ID_NOT_REGISTERED)
return BM_CONTENTION_OUTCOME_IRM_HOLDS_ANOTHER_NODE_AS_BM;
else
return BM_CONTENTION_OUTCOME_IRM_HOLDS_LOCAL_NODE_AS_BM;
}
default:
if (!keep_this_irm) {
fw_notice(card, "BM lock failed (%s), making local node (%02x) root\n",
fw_rcode_string(rcode), local_id);
return BM_CONTENTION_OUTCOME_IRM_COMPLIES_1394_1995_ONLY;
} else {
return BM_CONTENTION_OUTCOME_IRM_IS_NOT_CAPABLE_FOR_IRM;
}
}
}
DEFINE_FREE(node_unref, struct fw_node *, if (_T) fw_node_put(_T))
DEFINE_FREE(card_unref, struct fw_card *, if (_T) fw_card_put(_T))
@@ -305,105 +401,40 @@ static void bm_work(struct work_struct *work)
local_id = card->local_node->node_id;
if (card->bm_generation != generation) {
bool grace = time_is_before_jiffies64(card->reset_jiffies + msecs_to_jiffies(125));
enum bm_contention_outcome result = contend_for_bm(card);
if (grace ||
(is_next_generation(generation, card->bm_generation) && !card->bm_abdicate)) {
// This first step is to figure out who is IRM and
// then try to become bus manager. If the IRM is not
// well defined (e.g. does not have an active link
// layer or does not responds to our lock request, we
// will have to do a little vigilante bus management.
// In that case, we do a goto into the gap count logic
// so that when we do the reset, we still optimize the
// gap count. That could well save a reset in the
// next generation.
__be32 data[2] = {
cpu_to_be32(BUS_MANAGER_ID_NOT_REGISTERED),
cpu_to_be32(local_id),
};
struct fw_device *irm_device = fw_node_get_device(card->irm_node);
bool irm_is_1394_1995_only = false;
bool keep_this_irm = false;
int rcode;
if (!card->irm_node->link_on) {
new_root_id = local_id;
fw_notice(card, "%s, making local node (%02x) root\n",
"IRM has link off", new_root_id);
goto pick_me;
}
if (irm_device && irm_device->config_rom) {
irm_is_1394_1995_only = (irm_device->config_rom[2] & 0x000000f0) == 0;
// Canon MV5i works unreliably if it is not root node.
keep_this_irm = irm_device->config_rom[3] >> 8 == CANON_OUI;
}
if (irm_is_1394_1995_only && !keep_this_irm) {
new_root_id = local_id;
fw_notice(card, "%s, making local node (%02x) root\n",
"IRM is not 1394a compliant", new_root_id);
goto pick_me;
}
rcode = fw_run_transaction(card, TCODE_LOCK_COMPARE_SWAP,
irm_id, generation, SCODE_100,
CSR_REGISTER_BASE + CSR_BUS_MANAGER_ID,
data, sizeof(data));
switch (rcode) {
case RCODE_GENERATION:
// Another bus reset, BM work has been rescheduled.
return;
case RCODE_SEND_ERROR:
// We have been unable to send the lock request due to
// some local problem. Let's try again later and hope
// that the problem has gone away by then.
fw_schedule_bm_work(card, msecs_to_jiffies(125));
return;
case RCODE_COMPLETE:
{
int bm_id = be32_to_cpu(data[0]);
// Used by cdev layer for "struct fw_cdev_event_bus_reset".
scoped_guard(spinlock, &card->lock) {
if (bm_id != BUS_MANAGER_ID_NOT_REGISTERED)
card->bm_node_id = 0xffc0 & bm_id;
else
card->bm_node_id = local_id;
}
if (bm_id != BUS_MANAGER_ID_NOT_REGISTERED) {
// Somebody else is BM. Only act as IRM.
if (local_id == irm_id)
allocate_broadcast_channel(card, generation);
return;
}
break;
}
default:
if (!keep_this_irm) {
// The lock request failed, maybe the IRM
// isn't really IRM capable after all. Let's
// do a bus reset and pick the local node as
// root, and thus, IRM.
new_root_id = local_id;
fw_notice(card, "BM lock failed (%s), making local node (%02x) root\n",
fw_rcode_string(rcode), new_root_id);
goto pick_me;
}
break;
}
// A node contends for bus manager in this generation.
card->bm_generation = generation;
} else {
// We weren't BM in the last generation, and the last
// bus reset is less than 125ms ago. Reschedule this job.
switch (result) {
case BM_CONTENTION_OUTCOME_WITHIN_WINDOW:
fw_schedule_bm_work(card, msecs_to_jiffies(125));
return;
case BM_CONTENTION_OUTCOME_IRM_HAS_LINK_OFF:
new_root_id = local_id;
goto pick_me;
case BM_CONTENTION_OUTCOME_IRM_COMPLIES_1394_1995_ONLY:
new_root_id = local_id;
goto pick_me;
case BM_CONTENTION_OUTCOME_AT_NEW_GENERATION:
// BM work has been rescheduled.
return;
case BM_CONTENTION_OUTCOME_LOCAL_PROBLEM_AT_TRANSACTION:
// Let's try again later and hope that the local problem has gone away by
// then.
fw_schedule_bm_work(card, msecs_to_jiffies(125));
return;
case BM_CONTENTION_OUTCOME_IRM_IS_NOT_CAPABLE_FOR_IRM:
// Let's do a bus reset and pick the local node as root, and thus, IRM.
new_root_id = local_id;
goto pick_me;
case BM_CONTENTION_OUTCOME_IRM_HOLDS_ANOTHER_NODE_AS_BM:
if (local_id == irm_id) {
// Only acts as IRM.
allocate_broadcast_channel(card, generation);
}
fallthrough;
case BM_CONTENTION_OUTCOME_IRM_HOLDS_LOCAL_NODE_AS_BM:
default:
card->bm_generation = generation;
break;
}
}