firewire: octlet AT payloads can be stack-allocated
We do not need slab allocations anymore in order to satisfy
streaming DMA mapping constraints, thanks to commit da28947e7e36
"firewire: ohci: avoid separate DMA mapping for small AT payloads".
(Besides, the slab-allocated buffers that firewire-core, firewire-sbp2,
and firedtv used to provide for 8-byte write and lock requests were
still not fully portable since they crossed cacheline boundaries or
shared a cacheline with unrelated CPU-accessed data. snd-firewire-lib
got this aspect right by using an extra kmalloc/ kfree just for the
8-byte transaction buffer.)
This change replaces kmalloc'ed lock transaction scratch buffers in
firewire-core, firedtv, and snd-firewire-lib by local stack allocations.
Perhaps the most notable result of the change is simpler locking because
there is no need to serialize usages of preallocated per-device buffers
anymore. Also, allocations and deallocations are simpler.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Acked-by: Clemens Ladisch <clemens@ladisch.de>
diff --git a/drivers/firewire/core-iso.c b/drivers/firewire/core-iso.c
index 481056d..f872ede 100644
--- a/drivers/firewire/core-iso.c
+++ b/drivers/firewire/core-iso.c
@@ -196,9 +196,10 @@
*/
static int manage_bandwidth(struct fw_card *card, int irm_id, int generation,
- int bandwidth, bool allocate, __be32 data[2])
+ int bandwidth, bool allocate)
{
int try, new, old = allocate ? BANDWIDTH_AVAILABLE_INITIAL : 0;
+ __be32 data[2];
/*
* On a 1394a IRM with low contention, try < 1 is enough.
@@ -233,9 +234,10 @@
}
static int manage_channel(struct fw_card *card, int irm_id, int generation,
- u32 channels_mask, u64 offset, bool allocate, __be32 data[2])
+ u32 channels_mask, u64 offset, bool allocate)
{
__be32 bit, all, old;
+ __be32 data[2];
int channel, ret = -EIO, retry = 5;
old = all = allocate ? cpu_to_be32(~0) : 0;
@@ -284,7 +286,7 @@
}
static void deallocate_channel(struct fw_card *card, int irm_id,
- int generation, int channel, __be32 buffer[2])
+ int generation, int channel)
{
u32 mask;
u64 offset;
@@ -293,7 +295,7 @@
offset = channel < 32 ? CSR_REGISTER_BASE + CSR_CHANNELS_AVAILABLE_HI :
CSR_REGISTER_BASE + CSR_CHANNELS_AVAILABLE_LO;
- manage_channel(card, irm_id, generation, mask, offset, false, buffer);
+ manage_channel(card, irm_id, generation, mask, offset, false);
}
/**
@@ -322,7 +324,7 @@
*/
void fw_iso_resource_manage(struct fw_card *card, int generation,
u64 channels_mask, int *channel, int *bandwidth,
- bool allocate, __be32 buffer[2])
+ bool allocate)
{
u32 channels_hi = channels_mask; /* channels 31...0 */
u32 channels_lo = channels_mask >> 32; /* channels 63...32 */
@@ -335,11 +337,11 @@
if (channels_hi)
c = manage_channel(card, irm_id, generation, channels_hi,
CSR_REGISTER_BASE + CSR_CHANNELS_AVAILABLE_HI,
- allocate, buffer);
+ allocate);
if (channels_lo && c < 0) {
c = manage_channel(card, irm_id, generation, channels_lo,
CSR_REGISTER_BASE + CSR_CHANNELS_AVAILABLE_LO,
- allocate, buffer);
+ allocate);
if (c >= 0)
c += 32;
}
@@ -351,14 +353,13 @@
if (*bandwidth == 0)
return;
- ret = manage_bandwidth(card, irm_id, generation, *bandwidth,
- allocate, buffer);
+ ret = manage_bandwidth(card, irm_id, generation, *bandwidth, allocate);
if (ret < 0)
*bandwidth = 0;
if (allocate && ret < 0) {
if (c >= 0)
- deallocate_channel(card, irm_id, generation, c, buffer);
+ deallocate_channel(card, irm_id, generation, c);
*channel = ret;
}
}