Stefan Richter wrote: > ...provided that the allocation persists until the packet was sent out > to the bus. But 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. > The lifetime requirement of these allocations is fulfilled because the > call sites use the blocking fw_run_transaction API. > > 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. > > firewire-sbp2's struct sbp2_orb.pointer buffer for 8-byte block write > requests on the other hand needs to remain slab-allocated in order to > keep the allocation around until end of AT DMA. > > Signed-off-by: Stefan Richter <stefanr@xxxxxxxxxxxxxxxxx> Acked-by: Clemens Ladisch <clemens@xxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
