linux-kernel - [PATCH 2/6] firewire: core: maintain phy packet receivers locally in cdev layer

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Message-ID: <20250915234747.915922-3-o-takashi@sakamocchi.jp>
Date: Tue, 16 Sep 2025 08:47:43 +0900
From: Takashi Sakamoto <o-takashi@...amocchi.jp>
To: linux1394-devel@...ts.sourceforge.net
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH 2/6] firewire: core: maintain phy packet receivers locally in cdev layer

The list of receivers for phy packet is used only by cdev layer, while it
is maintained as a member of fw_card structure.

This commit maintains the list locally in cdev layer.

Signed-off-by: Takashi Sakamoto <o-takashi@...amocchi.jp>
---
 drivers/firewire/core-card.c |  1 -
 drivers/firewire/core-cdev.c | 27 ++++++++++++++++++++-------
 include/linux/firewire.h     |  2 --
 3 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/drivers/firewire/core-card.c b/drivers/firewire/core-card.c
index b5e01a711145..616abb836ef3 100644
--- a/drivers/firewire/core-card.c
+++ b/drivers/firewire/core-card.c
@@ -556,7 +556,6 @@ void fw_card_initialize(struct fw_card *card,
 	kref_init(&card->kref);
 	init_completion(&card->done);
 	INIT_LIST_HEAD(&card->transaction_list);
-	INIT_LIST_HEAD(&card->phy_receiver_list);
 	spin_lock_init(&card->lock);
 
 	card->local_node = NULL;
diff --git a/drivers/firewire/core-cdev.c b/drivers/firewire/core-cdev.c
index 1be8f5eb3e17..112b33099610 100644
--- a/drivers/firewire/core-cdev.c
+++ b/drivers/firewire/core-cdev.c
@@ -47,6 +47,9 @@
 #define FW_CDEV_VERSION_AUTO_FLUSH_ISO_OVERFLOW	5
 #define FW_CDEV_VERSION_EVENT_ASYNC_TSTAMP	6
 
+static DEFINE_SPINLOCK(phy_receiver_list_lock);
+static LIST_HEAD(phy_receiver_list);
+
 struct client {
 	u32 version;
 	struct fw_device *device;
@@ -1669,15 +1672,16 @@ static int ioctl_send_phy_packet(struct client *client, union ioctl_arg *arg)
 static int ioctl_receive_phy_packets(struct client *client, union ioctl_arg *arg)
 {
 	struct fw_cdev_receive_phy_packets *a = &arg->receive_phy_packets;
-	struct fw_card *card = client->device->card;
 
 	/* Access policy: Allow this ioctl only on local nodes' device files. */
 	if (!client->device->is_local)
 		return -ENOSYS;
 
-	guard(spinlock_irq)(&card->lock);
+	// NOTE: This can be without irq when we can guarantee that __fw_send_request() for local
+	// destination never runs in any type of IRQ context.
+	scoped_guard(spinlock_irq, &phy_receiver_list_lock)
+		list_move_tail(&client->phy_receiver_link, &phy_receiver_list);
 
-	list_move_tail(&client->phy_receiver_link, &card->phy_receiver_list);
 	client->phy_receiver_closure = a->closure;
 
 	return 0;
@@ -1687,10 +1691,17 @@ void fw_cdev_handle_phy_packet(struct fw_card *card, struct fw_packet *p)
 {
 	struct client *client;
 
-	guard(spinlock_irqsave)(&card->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.
+	guard(spinlock_irqsave)(&phy_receiver_list_lock);
+
+	list_for_each_entry(client, &phy_receiver_list, phy_receiver_link) {
+		struct inbound_phy_packet_event *e;
+
+		if (client->device->card != card)
+			continue;
 
-	list_for_each_entry(client, &card->phy_receiver_list, phy_receiver_link) {
-		struct inbound_phy_packet_event *e = kmalloc(sizeof(*e) + 8, GFP_ATOMIC);
+		e = kmalloc(sizeof(*e) + 8, GFP_ATOMIC);
 		if (e == NULL)
 			break;
 
@@ -1857,7 +1868,9 @@ static int fw_device_op_release(struct inode *inode, struct file *file)
 	struct client_resource *resource;
 	unsigned long index;
 
-	scoped_guard(spinlock_irq, &client->device->card->lock)
+	// NOTE: This can be without irq when we can guarantee that __fw_send_request() for local
+	// destination never runs in any type of IRQ context.
+	scoped_guard(spinlock_irq, &phy_receiver_list_lock)
 		list_del(&client->phy_receiver_link);
 
 	scoped_guard(mutex, &client->device->client_list_mutex)
diff --git a/include/linux/firewire.h b/include/linux/firewire.h
index d38c6e538e5c..f3260aacf730 100644
--- a/include/linux/firewire.h
+++ b/include/linux/firewire.h
@@ -115,8 +115,6 @@ struct fw_card {
 	int index;
 	struct list_head link;
 
-	struct list_head phy_receiver_list;
-
 	struct delayed_work br_work; /* bus reset job */
 	bool br_short;
 
-- 
2.48.1