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>

1 files changed, 1 insertions, 2 deletions

diff --git a/include/linux/firewire.h b/include/linux/firewire.h
index c64f3680d4f1..de90e1ff8488 100644
--- a/include/linux/firewire.h
+++ b/include/linux/firewire.h
@@ -125,7 +125,6 @@ struct fw_card {
         struct delayed_work bm_work; /* bus manager job */
         int bm_retries;
         int bm_generation;
-        __be32 bm_transaction_data[2];
         int bm_node_id;
         bool bm_abdicate;
 
@@ -447,6 +446,6 @@ int fw_iso_context_stop(struct fw_iso_context *ctx);
 void fw_iso_context_destroy(struct fw_iso_context *ctx);
 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);
 
 #endif /* _LINUX_FIREWIRE_H */