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Subject[PATCH] firewire: fw-ohci: fix possible IOMMU resource exhaustion
There is a DMA map/ unmap imbalance whenever a block write request
packet is sent and then dequeued with ohci_cancel_packet. The latter
may happen frequently if the AR resp tasklet is executed before the AT
req tasklet for the same transaction.

Add the missing dma_unmap_single.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
---

This was spotted due to https://bugzilla.redhat.com/show_bug.cgi?id=475156,
but whether the patch already fixes bug 475156 has yet to be tested.

drivers/firewire/fw-ohci.c | 11 +++++++----
drivers/firewire/fw-transaction.c | 3 +++
drivers/firewire/fw-transaction.h | 2 ++
3 files changed, 12 insertions(+), 4 deletions(-)

Index: linux/drivers/firewire/fw-ohci.c
===================================================================
--- linux.orig/drivers/firewire/fw-ohci.c
+++ linux/drivers/firewire/fw-ohci.c
@@ -974,6 +974,7 @@ at_context_queue_packet(struct context *
packet->ack = RCODE_SEND_ERROR;
return -1;
}
+ packet->payload_bus = payload_bus;

d[2].req_count = cpu_to_le16(packet->payload_length);
d[2].data_address = cpu_to_le32(payload_bus);
@@ -1025,7 +1026,6 @@ static int handle_at_packet(struct conte
struct driver_data *driver_data;
struct fw_packet *packet;
struct fw_ohci *ohci = context->ohci;
- dma_addr_t payload_bus;
int evt;

if (last->transfer_status == 0)
@@ -1038,9 +1038,8 @@ static int handle_at_packet(struct conte
/* This packet was cancelled, just continue. */
return 1;

- payload_bus = le32_to_cpu(last->data_address);
- if (payload_bus != 0)
- dma_unmap_single(ohci->card.device, payload_bus,
+ if (packet->payload_bus)
+ dma_unmap_single(ohci->card.device, packet->payload_bus,
packet->payload_length, DMA_TO_DEVICE);

evt = le16_to_cpu(last->transfer_status) & 0x1f;
@@ -1697,6 +1696,10 @@ static int ohci_cancel_packet(struct fw_
if (packet->ack != 0)
goto out;

+ if (packet->payload_bus)
+ dma_unmap_single(ohci->card.device, packet->payload_bus,
+ packet->payload_length, DMA_TO_DEVICE);
+
log_ar_at_event('T', packet->speed, packet->header, 0x20);
driver_data->packet = NULL;
packet->ack = RCODE_CANCELLED;
Index: linux/drivers/firewire/fw-transaction.c
===================================================================
--- linux.orig/drivers/firewire/fw-transaction.c
+++ linux/drivers/firewire/fw-transaction.c
@@ -208,6 +208,7 @@ fw_fill_request(struct fw_packet *packet
packet->speed = speed;
packet->generation = generation;
packet->ack = 0;
+ packet->payload_bus = 0;
}

/**
@@ -582,6 +583,8 @@ fw_fill_response(struct fw_packet *respo
BUG();
return;
}
+
+ response->payload_bus = 0;
}
EXPORT_SYMBOL(fw_fill_response);

Index: linux/drivers/firewire/fw-transaction.h
===================================================================
--- linux.orig/drivers/firewire/fw-transaction.h
+++ linux/drivers/firewire/fw-transaction.h
@@ -27,6 +27,7 @@
#include <linux/list.h>
#include <linux/spinlock_types.h>
#include <linux/timer.h>
+#include <linux/types.h>
#include <linux/workqueue.h>

#define TCODE_IS_READ_REQUEST(tcode) (((tcode) & ~1) == 4)
@@ -153,6 +154,7 @@ struct fw_packet {
size_t header_length;
void *payload;
size_t payload_length;
+ dma_addr_t payload_bus;
u32 timestamp;

/*
--
Stefan Richter
-=====-==--- ==-- -=-=-
http://arcgraph.de/sr/


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