firewire: core: code refactoring to evaluate transaction result to CSR_BUS_MANAGER_ID

The call of bm_work should be done after acquiring spin lock of fw_card.
For asynchronous transaction, the lock should be released temporarily
due to event waiting.

A commit 27310d561622 ("firewire: core: use guard macro to maintain
properties of fw_card") applied scoped_guard() to the bm_work function,
however it looks hard to follow to the control flow.

This commit refactors the spin lock acquisition after the transaction.

Link: https://lore.kernel.org/r/20250908012108.514698-8-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>

diff --git a/drivers/firewire/core-card.c b/drivers/firewire/core-card.c
index b98797e..e1a7a15 100644 (file)
--- a/drivers/firewire/core-card.c
+++ b/drivers/firewire/core-card.c
@@ -291,7 +291,7 @@ static void bm_work(struct work_struct *work)
        struct fw_card *card __free(card_unref) = from_work(card, work, bm_work.work);
        struct fw_device *root_device, *irm_device;
        struct fw_node *root_node __free(node_unref) = NULL;
-       int root_id, new_root_id, irm_id, bm_id, local_id;
+       int root_id, new_root_id, irm_id, local_id;
        int gap_count, generation, grace;
        bool do_reset = false;
        bool root_device_is_running;
@@ -376,19 +376,22 @@ static void bm_work(struct work_struct *work)
                if (rcode == RCODE_GENERATION)
                        return;
 
-               bm_id = be32_to_cpu(data[0]);
+               spin_lock_irq(&card->lock);
 
-               scoped_guard(spinlock_irq, &card->lock) {
-                       if (rcode == RCODE_COMPLETE && generation == card->generation)
-                               card->bm_node_id =
-                                   bm_id == 0x3f ? local_id : 0xffc0 | bm_id;
-               }
+               if (rcode == RCODE_COMPLETE) {
+                       int bm_id = be32_to_cpu(data[0]);
 
-               if (rcode == RCODE_COMPLETE && bm_id != 0x3f) {
-                       /* Somebody else is BM.  Only act as IRM. */
-                       if (local_id == irm_id)
-                               allocate_broadcast_channel(card, generation);
-                       return;
+                       if (generation == card->generation)
+                               card->bm_node_id = bm_id == 0x3f ? local_id : 0xffc0 | bm_id;
+
+                       if (bm_id != 0x3f) {
+                               spin_unlock_irq(&card->lock);
+
+                               // Somebody else is BM.  Only act as IRM.
+                               if (local_id == irm_id)
+                                       allocate_broadcast_channel(card, generation);
+                               return;
+                       }
                }
 
                if (rcode == RCODE_SEND_ERROR) {
@@ -397,12 +400,11 @@ static void bm_work(struct work_struct *work)
                         * some local problem.  Let's try again later and hope
                         * that the problem has gone away by then.
                         */
+                       spin_unlock_irq(&card->lock);
                        fw_schedule_bm_work(card, DIV_ROUND_UP(HZ, 8));
                        return;
                }
 
-               spin_lock_irq(&card->lock);
-
                if (rcode != RCODE_COMPLETE && !keep_this_irm) {
                        /*
                         * The lock request failed, maybe the IRM