Date: Wed, 14 Oct 2009 20:40:10 +0200 (CEST) From: Stefan Richter Subject: firewire: ohci: 0 may be a valid DMA address I was told that there are obscure architectures with non-coherent DMA which may DMA-map to bus address 0. We shall not use 0 as a magic number of uninitialized bus address variables. The packet->payload_length > 0 test cannot be used either (except in at_context_queue_packet) because local requests are not DMA-mapped regardless of payload_length. Hence add a state flag to struct fw_packet. Signed-off-by: Stefan Richter --- drivers/firewire/core-transaction.c | 4 ++-- drivers/firewire/ohci.c | 9 +++++---- include/linux/firewire.h | 1 + 3 files changed, 8 insertions(+), 6 deletions(-) Index: linux-2.6.31/drivers/firewire/ohci.c =================================================================== --- linux-2.6.31.orig/drivers/firewire/ohci.c +++ linux-2.6.31/drivers/firewire/ohci.c @@ -995,7 +995,8 @@ static int at_context_queue_packet(struc packet->ack = RCODE_SEND_ERROR; return -1; } - packet->payload_bus = payload_bus; + packet->payload_bus = payload_bus; + packet->payload_mapped = true; d[2].req_count = cpu_to_le16(packet->payload_length); d[2].data_address = cpu_to_le32(payload_bus); @@ -1023,7 +1024,7 @@ static int at_context_queue_packet(struc */ if (ohci->generation != packet->generation || reg_read(ohci, OHCI1394_IntEventSet) & OHCI1394_busReset) { - if (packet->payload_length > 0) + if (packet->payload_mapped) dma_unmap_single(ohci->card.device, payload_bus, packet->payload_length, DMA_TO_DEVICE); packet->ack = RCODE_GENERATION; @@ -1059,7 +1060,7 @@ static int handle_at_packet(struct conte /* This packet was cancelled, just continue. */ return 1; - if (packet->payload_bus) + if (packet->payload_mapped) dma_unmap_single(ohci->card.device, packet->payload_bus, packet->payload_length, DMA_TO_DEVICE); @@ -1723,7 +1724,7 @@ static int ohci_cancel_packet(struct fw_ if (packet->ack != 0) goto out; - if (packet->payload_bus) + if (packet->payload_mapped) dma_unmap_single(ohci->card.device, packet->payload_bus, packet->payload_length, DMA_TO_DEVICE); Index: linux-2.6.31/drivers/firewire/core-transaction.c =================================================================== --- linux-2.6.31.orig/drivers/firewire/core-transaction.c +++ linux-2.6.31/drivers/firewire/core-transaction.c @@ -226,7 +226,7 @@ static void fw_fill_request(struct fw_pa packet->speed = speed; packet->generation = generation; packet->ack = 0; - packet->payload_bus = 0; + packet->payload_mapped = false; } /** @@ -601,7 +601,7 @@ void fw_fill_response(struct fw_packet * WARN(1, KERN_ERR "wrong tcode %d", tcode); } - response->payload_bus = 0; + response->payload_mapped = false; } EXPORT_SYMBOL(fw_fill_response); Index: linux-2.6.31/include/linux/firewire.h =================================================================== --- linux-2.6.31.orig/include/linux/firewire.h +++ linux-2.6.31/include/linux/firewire.h @@ -267,6 +267,7 @@ struct fw_packet { void *payload; size_t payload_length; dma_addr_t payload_bus; + bool payload_mapped; u32 timestamp; /*