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firewire: octlet AT payloads can be stack-allocated

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We do not need slab allocations anymore in order to satisfy
streaming DMA mapping constraints, thanks to commit da28947e7e
"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>
This commit is contained in:
Stefan Richter
2011-04-22 15:13:54 +02:00
parent 020abf03cd
commit f30e6d3e41
9 changed files with 30 additions and 52 deletions
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3
sound/firewire/cmp.c
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@@ -49,10 +49,9 @@ static int pcr_modify(struct cmp_connection *c,
enum bus_reset_handling bus_reset_handling)
{
struct fw_device *device = fw_parent_device(c->resources.unit);
__be32 *buffer = c->resources.buffer;
int generation = c->resources.generation;
int rcode, errors = 0;
__be32 old_arg;
__be32 old_arg, buffer[2];
int err;
buffer[0] = c->last_pcr_value;