firewire: core: use context analysis annotations and lockdep checks for transactions lock

The transaction lock protects the list of pending transactions and the
transaction label.

Add context analysis annotations for the transaction lock. Compiler-based
context analysis has difficulty tracking the locking scope when the lock
is accessed through an indirect reference (e.g. t->card->lock), making
some functions difficult to annotate. Use lockdep assertions to cover
these cases.

Link: https://lore.kernel.org/r/20261011063146.497455-4-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>

drivers/firewire/core-transaction.c

@@ -36,18 +36,24 @@
 #define HEADER_DESTINATION_IS_BROADCAST(header) \
 	((async_header_get_destination(header) & 0x3f) == 0x3f)
 
-/* returns 0 if the split timeout handler is already running */
+// Returns 0 if the split timeout handler is already running.
+//
+// card->transactions.lock must be acquired in advance.
 static int try_cancel_split_timeout(struct fw_transaction *t)
 {
+	lockdep_assert_held(&t->card->transactions.lock);
+
 	if (t->is_split_transaction)
 		return timer_delete(&t->split_timeout_timer) || disable_work(&t->error_work);
 	else
 		return 1;
 }
 
-// card->transactions.lock must be acquired in advance.
 static void remove_transaction_entry(struct fw_card *card, struct fw_transaction *entry)
+__must_hold(&card->transactions.lock)
 {
+	lockdep_assert_held(&card->transactions.lock);
+
 	list_del_init(&entry->link);
 	card->transactions.tlabel_mask &= ~(1ULL << entry->tlabel);
 }
@@ -65,10 +71,13 @@ static void invoke_callback(struct fw_transaction *t, int rcode, u32 response_ts
 
 // Must be called without holding card->transactions.lock.
 void fw_cancel_pending_transactions(struct fw_card *card)
+__must_not_hold(&card->transactions.lock)
 {
 	struct fw_transaction *t, *tmp;
 	LIST_HEAD(pending_list);
 
+	lockdep_assert_not_held(&card->transactions.lock);
+
 	// NOTE: This can be without irqsave when we can guarantee that __fw_send_request() for
 	// local destination never runs in any type of IRQ context.
 	scoped_guard(spinlock_irqsave, &card->transactions.lock) {
@@ -117,7 +126,10 @@ void fw_cancel_pending_transactions(struct fw_card *card)
  * pending transaction.
  */
 int fw_cancel_transaction(struct fw_card *card, struct fw_transaction *transaction)
+__must_not_hold(&card->transactions.lock)
 {
+	lockdep_assert_not_held(&card->transactions.lock);
+
 	// Allow the call of struct fw_card_driver.cancel_packet() to wait for any event.
 	might_sleep();
 
@@ -164,11 +176,14 @@ static void schedule_error_callback(struct fw_transaction *t, int rcode, u32 res
 	queue_work(t->card->async_wq, &t->error_work);
 }
 
+// card->transactions.lock must be released in advance.
 static void split_transaction_timeout_callback(struct timer_list *timer)
 {
 	struct fw_transaction *t = timer_container_of(t, timer, split_timeout_timer);
 	struct fw_card *card = t->card;
 
+	lockdep_assert_not_held(&card->transactions.lock);
+
 	scoped_guard(spinlock_irqsave, &card->transactions.lock) {
 		if (list_empty(&t->link))
 			return;
@@ -181,6 +196,8 @@ static void split_transaction_timeout_callback(struct timer_list *timer)
 // card->transactions.lock should be acquired in advance for the linked list.
 static void start_split_transaction_timeout(struct fw_transaction *t, unsigned int delta)
 {
+	lockdep_assert_held(&t->card->transactions.lock);
+
 	if (list_empty(&t->link) || WARN_ON(t->is_split_transaction))
 		return;
 
@@ -193,10 +210,13 @@ static u32 compute_split_timeout_timestamp(struct fw_card *card, u32 request_tim
 
 static void transmit_complete_callback(struct fw_packet *packet,
 				       struct fw_card *card, int status)
+__must_not_hold(&card->transactions.lock)
 {
 	struct fw_transaction *t =
 	    container_of(packet, struct fw_transaction, packet);
 
+	lockdep_assert_not_held(&card->transactions.lock);
+
 	trace_async_request_outbound_complete((uintptr_t)t, card->index, packet->generation,
 					      packet->speed, status, packet->timestamp);
 
@@ -392,9 +412,12 @@ void __fw_send_request(struct fw_card *card, struct fw_transaction *t, int tcode
 		int destination_id, int generation, int speed, unsigned long long offset,
 		void *payload, size_t length, union fw_transaction_callback callback,
 		bool with_tstamp, void *callback_data)
+__must_not_hold(&card->transactions.lock)
 {
 	int tlabel;
 
+	lockdep_assert_not_held(&card->transactions.lock);
+
 	t->card = card;
 	t->callback = callback;
 	t->with_tstamp = with_tstamp;
@@ -1156,12 +1179,15 @@ void fw_core_handle_request(struct fw_card *card, struct fw_packet *p)
 EXPORT_SYMBOL(fw_core_handle_request);
 
 void fw_core_handle_response(struct fw_card *card, struct fw_packet *p)
+__must_not_hold(&card->transactions.lock)
 {
 	struct fw_transaction *t = NULL;
 	u32 *data;
 	size_t data_length;
 	int tcode, tlabel, source, rcode;
 
+	lockdep_assert_not_held(&card->transactions.lock);
+
 	// Allow the call of struct fw_card_driver.cancel_packet() to wait for any event.
 	might_sleep();
 

include/linux/firewire.h

@@ -92,9 +92,9 @@ struct fw_card {
 	u64 reset_jiffies;
 
 	struct {
-		int current_tlabel;
-		u64 tlabel_mask;
-		struct list_head list;
+		int current_tlabel __guarded_by(&lock);
+		u64 tlabel_mask __guarded_by(&lock);
+		struct list_head list __guarded_by(&lock);
 		spinlock_t lock;
 	} transactions;