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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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16
drivers/firewire/core-card.c
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@@ -258,8 +258,7 @@ static void allocate_broadcast_channel(struct fw_card *card, int generation)
if (!card->broadcast_channel_allocated) {
fw_iso_resource_manage(card, generation, 1ULL << 31,
&channel, &bandwidth, true,
card->bm_transaction_data);
&channel, &bandwidth, true);
if (channel != 31) {
fw_notify("failed to allocate broadcast channel\n");
return;
@@ -294,6 +293,7 @@ static void bm_work(struct work_struct *work)
bool root_device_is_cmc;
bool irm_is_1394_1995_only;
bool keep_this_irm;
__be32 transaction_data[2];
spin_lock_irq(&card->lock);
@@ -355,21 +355,21 @@ static void bm_work(struct work_struct *work)
goto pick_me;
}
card->bm_transaction_data[0] = cpu_to_be32(0x3f);
card->bm_transaction_data[1] = cpu_to_be32(local_id);
transaction_data[0] = cpu_to_be32(0x3f);
transaction_data[1] = cpu_to_be32(local_id);
spin_unlock_irq(&card->lock);
rcode = fw_run_transaction(card, TCODE_LOCK_COMPARE_SWAP,
irm_id, generation, SCODE_100,
CSR_REGISTER_BASE + CSR_BUS_MANAGER_ID,
card->bm_transaction_data, 8);
transaction_data, 8);
if (rcode == RCODE_GENERATION)
/* Another bus reset, BM work has been rescheduled. */
goto out;
bm_id = be32_to_cpu(card->bm_transaction_data[0]);
bm_id = be32_to_cpu(transaction_data[0]);
spin_lock_irq(&card->lock);
if (rcode == RCODE_COMPLETE && generation == card->generation)
@@ -490,11 +490,11 @@ static void bm_work(struct work_struct *work)
/*
* Make sure that the cycle master sends cycle start packets.
*/
card->bm_transaction_data[0] = cpu_to_be32(CSR_STATE_BIT_CMSTR);
transaction_data[0] = cpu_to_be32(CSR_STATE_BIT_CMSTR);
rcode = fw_run_transaction(card, TCODE_WRITE_QUADLET_REQUEST,
root_id, generation, SCODE_100,
CSR_REGISTER_BASE + CSR_STATE_SET,
card->bm_transaction_data, 4);
transaction_data, 4);
if (rcode == RCODE_GENERATION)
goto out;
}