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Message-ID: <20250924131823.262136-2-o-takashi@sakamocchi.jp>
Date: Wed, 24 Sep 2025 22:18:22 +0900
From: Takashi Sakamoto <o-takashi@...amocchi.jp>
To: linux1394-devel@...ts.sourceforge.net
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH v2 1/2] Revert "firewire: core: shrink critical section of fw_card spinlock in bm_work"
This reverts commit 582310376d6e9a8d261b682178713cdc4b251af6.
The bus manager work has the race condition against fw_destroy_nodes()
called by fw_core_remove_card(). The acquition of spin lock of fw_card
is left as is again.
Signed-off-by: Takashi Sakamoto <o-takashi@...amocchi.jp>
---
drivers/firewire/core-card.c | 38 ++++++++++++++++++++++++++++--------
1 file changed, 30 insertions(+), 8 deletions(-)
diff --git a/drivers/firewire/core-card.c b/drivers/firewire/core-card.c
index 4a5459696093..e5e0174a0335 100644
--- a/drivers/firewire/core-card.c
+++ b/drivers/firewire/core-card.c
@@ -299,6 +299,7 @@ enum bm_contention_outcome {
};
static enum bm_contention_outcome contend_for_bm(struct fw_card *card)
+__must_hold(&card->lock)
{
int generation = card->generation;
int local_id = card->local_node->node_id;
@@ -311,8 +312,11 @@ static enum bm_contention_outcome contend_for_bm(struct fw_card *card)
bool keep_this_irm = false;
struct fw_node *irm_node;
struct fw_device *irm_device;
+ int irm_node_id;
int rcode;
+ lockdep_assert_held(&card->lock);
+
if (!grace) {
if (!is_next_generation(generation, card->bm_generation) || card->bm_abdicate)
return BM_CONTENTION_OUTCOME_WITHIN_WINDOW;
@@ -338,10 +342,16 @@ static enum bm_contention_outcome contend_for_bm(struct fw_card *card)
return BM_CONTENTION_OUTCOME_IRM_COMPLIES_1394_1995_ONLY;
}
- rcode = fw_run_transaction(card, TCODE_LOCK_COMPARE_SWAP, irm_node->node_id, generation,
+ irm_node_id = irm_node->node_id;
+
+ spin_unlock_irq(&card->lock);
+
+ rcode = fw_run_transaction(card, TCODE_LOCK_COMPARE_SWAP, irm_node_id, generation,
SCODE_100, CSR_REGISTER_BASE + CSR_BUS_MANAGER_ID, data,
sizeof(data));
+ spin_lock_irq(&card->lock);
+
switch (rcode) {
case RCODE_GENERATION:
return BM_CONTENTION_OUTCOME_AT_NEW_GENERATION;
@@ -352,12 +362,10 @@ static enum bm_contention_outcome contend_for_bm(struct fw_card *card)
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)
+ 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;
@@ -389,8 +397,12 @@ static void bm_work(struct work_struct *work)
int expected_gap_count, generation;
bool stand_for_root = false;
- if (card->local_node == NULL)
+ spin_lock_irq(&card->lock);
+
+ if (card->local_node == NULL) {
+ spin_unlock_irq(&card->lock);
return;
+ }
generation = card->generation;
@@ -405,6 +417,7 @@ static void bm_work(struct work_struct *work)
switch (result) {
case BM_CONTENTION_OUTCOME_WITHIN_WINDOW:
+ spin_unlock_irq(&card->lock);
fw_schedule_bm_work(card, msecs_to_jiffies(125));
return;
case BM_CONTENTION_OUTCOME_IRM_HAS_LINK_OFF:
@@ -415,10 +428,12 @@ static void bm_work(struct work_struct *work)
break;
case BM_CONTENTION_OUTCOME_AT_NEW_GENERATION:
// BM work has been rescheduled.
+ spin_unlock_irq(&card->lock);
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.
+ spin_unlock_irq(&card->lock);
fw_schedule_bm_work(card, msecs_to_jiffies(125));
return;
case BM_CONTENTION_OUTCOME_IRM_IS_NOT_CAPABLE_FOR_IRM:
@@ -428,7 +443,9 @@ static void bm_work(struct work_struct *work)
case BM_CONTENTION_OUTCOME_IRM_HOLDS_ANOTHER_NODE_AS_BM:
if (local_id == irm_id) {
// Only acts as IRM.
+ spin_unlock_irq(&card->lock);
allocate_broadcast_channel(card, generation);
+ spin_lock_irq(&card->lock);
}
fallthrough;
case BM_CONTENTION_OUTCOME_IRM_HOLDS_LOCAL_NODE_AS_BM:
@@ -469,6 +486,7 @@ static void bm_work(struct work_struct *work)
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_irq(&card->lock);
return;
} else if (!root_device->cmc) {
// Current root has an active link layer and we
@@ -504,6 +522,8 @@ static void bm_work(struct work_struct *work)
if (card->bm_retries++ < 5 && (card->gap_count != expected_gap_count || new_root_id != root_id)) {
int card_gap_count = card->gap_count;
+ spin_unlock_irq(&card->lock);
+
fw_notice(card, "phy config: new root=%x, gap_count=%d\n",
new_root_id, expected_gap_count);
fw_send_phy_config(card, new_root_id, generation, expected_gap_count);
@@ -524,6 +544,8 @@ static void bm_work(struct work_struct *work)
} else {
struct fw_device *root_device = fw_node_get_device(root_node);
+ spin_unlock_irq(&card->lock);
+
if (root_device && root_device->cmc) {
// Make sure that the cycle master sends cycle start packets.
__be32 data = cpu_to_be32(CSR_STATE_BIT_CMSTR);
--
2.48.1
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