Commit 7d138cb2 authored by Takashi Sakamoto's avatar Takashi Sakamoto
Browse files

firewire: core: use spin lock specific to topology map 

At present, the operation for read transaction to topology map register is
not protected by any kind of lock primitives. This causes a potential
problem to result in the mixed content of topology map.

This commit adds and uses spin lock specific to topology map.

Link: https://lore.kernel.org/r/20250915234747.915922-4-o-takashi@sakamocchi.jp


Signed-off-by: default avatarTakashi Sakamoto <o-takashi@sakamocchi.jp>
parent 07c446e3

drivers/firewire/core-topology.c

+14 −8
Original line number Diff line number Diff line
@@ -435,20 +435,22 @@ static void update_tree(struct fw_card *card, struct fw_node *root) 
	}

}



static void update_topology_map(struct fw_card *card,

				u32 *self_ids, int self_id_count)

static void update_topology_map(__be32 *buffer, size_t buffer_size, int root_node_id,

				const u32 *self_ids, int self_id_count)

{

	int node_count = (card->root_node->node_id & 0x3f) + 1;

	__be32 *map = card->topology_map;

	__be32 *map = buffer;

	int node_count = (root_node_id & 0x3f) + 1;



	memset(map, 0, buffer_size);



	*map++ = cpu_to_be32((self_id_count + 2) << 16);

	*map++ = cpu_to_be32(be32_to_cpu(card->topology_map[1]) + 1);

	*map++ = cpu_to_be32(be32_to_cpu(buffer[1]) + 1);

	*map++ = cpu_to_be32((node_count << 16) | self_id_count);



	while (self_id_count--)

		*map++ = cpu_to_be32p(self_ids++);



	fw_compute_block_crc(card->topology_map);

	fw_compute_block_crc(buffer);

}



void fw_core_handle_bus_reset(struct fw_card *card, int node_id, int generation,
@@ -479,8 +481,6 @@ void fw_core_handle_bus_reset(struct fw_card *card, int node_id, int generation, 


		local_node = build_tree(card, self_ids, self_id_count, generation);



		update_topology_map(card, self_ids, self_id_count);



		card->color++;



		if (local_node == NULL) {
@@ -493,5 +493,11 @@ void fw_core_handle_bus_reset(struct fw_card *card, int node_id, int generation, 
			update_tree(card, local_node);

		}

	}



	// Just used by transaction layer.

	scoped_guard(spinlock, &card->topology_map.lock) {

		update_topology_map(card->topology_map.buffer, sizeof(card->topology_map.buffer),

				    card->root_node->node_id, self_ids, self_id_count);

	}

}

EXPORT_SYMBOL(fw_core_handle_bus_reset);

drivers/firewire/core-transaction.c

+5 −1
Original line number Diff line number Diff line
@@ -1196,7 +1196,11 @@ static void handle_topology_map(struct fw_card *card, struct fw_request *request 
	}



	start = (offset - topology_map_region.start) / 4;

	memcpy(payload, &card->topology_map[start], length);



	// 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->topology_map.lock)

		memcpy(payload, &card->topology_map.buffer[start], length);



	fw_send_response(card, request, RCODE_COMPLETE);

}

include/linux/firewire.h

+5 −1
Original line number Diff line number Diff line
@@ -129,7 +129,11 @@ struct fw_card { 


	bool broadcast_channel_allocated;

	u32 broadcast_channel;

	__be32 topology_map[(CSR_TOPOLOGY_MAP_END - CSR_TOPOLOGY_MAP) / 4];



	struct {

		__be32 buffer[(CSR_TOPOLOGY_MAP_END - CSR_TOPOLOGY_MAP) / 4];

		spinlock_t lock;

	} topology_map;



	__be32 maint_utility_register;