From 8c0c0cc2d9f4c523fde04bdfe41e4380dec8ee54 Mon Sep 17 00:00:00 2001
From: Jay Fenlason <fenlason@redhat.com>
Date: Fri, 11 Dec 2009 14:23:58 -0500
Subject: [PATCH] firewire: ohci: handle receive packets with a data length of
zero
Queueing to receive an ISO packet with a payload length of zero
silently does nothing in dualbuffer mode, and crashes the kernel in
packet-per-buffer mode. Return an error in dualbuffer mode, because
the DMA controller won't let us do what we want, and work correctly in
packet-per-buffer mode.
Signed-off-by: Jay Fenlason <fenlason@redhat.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Cc: stable@kernel.org
---
drivers/firewire/ohci.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c
index a71477541dc7e..553c74e1e4e3f 100644
--- a/drivers/firewire/ohci.c
+++ b/drivers/firewire/ohci.c
@@ -2189,6 +2189,13 @@ static int ohci_queue_iso_receive_dualbuffer(struct fw_iso_context *base,
page = payload >> PAGE_SHIFT;
offset = payload & ~PAGE_MASK;
rest = p->payload_length;
+ /*
+ * The controllers I've tested have not worked correctly when
+ * second_req_count is zero. Rather than do something we know won't
+ * work, return an error
+ */
+ if (rest == 0)
+ return -EINVAL;
/* FIXME: make packet-per-buffer/dual-buffer a context option */
while (rest > 0) {
@@ -2242,7 +2249,7 @@ static int ohci_queue_iso_receive_packet_per_buffer(struct fw_iso_context *base,
unsigned long payload)
{
struct iso_context *ctx = container_of(base, struct iso_context, base);
- struct descriptor *d = NULL, *pd = NULL;
+ struct descriptor *d, *pd;
struct fw_iso_packet *p = packet;
dma_addr_t d_bus, page_bus;
u32 z, header_z, rest;
@@ -2280,8 +2287,9 @@ static int ohci_queue_iso_receive_packet_per_buffer(struct fw_iso_context *base,
d->data_address = cpu_to_le32(d_bus + (z * sizeof(*d)));
rest = payload_per_buffer;
+ pd = d;
for (j = 1; j < z; j++) {
- pd = d + j;
+ pd++;
pd->control = cpu_to_le16(DESCRIPTOR_STATUS |
DESCRIPTOR_INPUT_MORE);
--
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