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 <stefanr@s5r6.in-berlin.de>

diff --git a/drivers/firewire/core-transaction.c b/drivers/firewire/core-transaction.c
index 66789c3..842739d 100644 (file)
--- a/drivers/firewire/core-transaction.c
+++ b/drivers/firewire/core-transaction.c
@@ -226,7 +226,7 @@ static void fw_fill_request(struct fw_packet *packet, int tcode, int tlabel,
        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 *response, u32 *request_header,
                WARN(1, KERN_ERR "wrong tcode %d", tcode);
        }
 
-       response->payload_bus = 0;
+       response->payload_mapped = false;
 }
 EXPORT_SYMBOL(fw_fill_response);
 

diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c
index 4184155..a714775 100644 (file)
--- a/drivers/firewire/ohci.c
+++ b/drivers/firewire/ohci.c
@@ -995,7 +995,8 @@ static int at_context_queue_packet(struct context *ctx,
                        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(struct context *ctx,
         */
        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 context *context,
                /* 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_card *card, struct fw_packet *packet)
        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);
 

diff --git a/include/linux/firewire.h b/include/linux/firewire.h
index 211a5d7..9416a46 100644 (file)
--- a/include/linux/firewire.h
+++ b/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;
 
        /*