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-card.c b/drivers/firewire/core-card.c
index 3c44fbc8..e119f1e 100644
--- a/drivers/firewire/core-card.c
+++ b/drivers/firewire/core-card.c
@@ -258,8 +258,7 @@
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 @@
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 @@
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 @@
/*
* 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;
}
diff --git a/drivers/firewire/core-cdev.c b/drivers/firewire/core-cdev.c
index 62ac111..2a3f1c4 100644
--- a/drivers/firewire/core-cdev.c
+++ b/drivers/firewire/core-cdev.c
@@ -141,7 +141,6 @@
int generation;
u64 channels;
s32 bandwidth;
- __be32 transaction_data[2];
struct iso_resource_event *e_alloc, *e_dealloc;
};
@@ -1229,8 +1228,7 @@
r->channels, &channel, &bandwidth,
todo == ISO_RES_ALLOC ||
todo == ISO_RES_REALLOC ||
- todo == ISO_RES_ALLOC_ONCE,
- r->transaction_data);
+ todo == ISO_RES_ALLOC_ONCE);
/*
* Is this generation outdated already? As long as this resource sticks
* in the idr, it will be scheduled again for a newer generation or at
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;
}
}
diff --git a/drivers/firewire/core-transaction.c b/drivers/firewire/core-transaction.c
index d00f8ce..77275fd 100644
--- a/drivers/firewire/core-transaction.c
+++ b/drivers/firewire/core-transaction.c
@@ -326,8 +326,8 @@
* It will contain tag, channel, and sy data instead of a node ID then.
*
* The payload buffer at @data is going to be DMA-mapped except in case of
- * quadlet-sized payload or of local (loopback) requests. Hence make sure that
- * the buffer complies with the restrictions for DMA-mapped memory. The
+ * @length <= 8 or of local (loopback) requests. Hence make sure that the
+ * buffer complies with the restrictions of the streaming DMA mapping API.
* @payload must not be freed before the @callback is called.
*
* In case of request types without payload, @data is NULL and @length is 0.
@@ -411,7 +411,8 @@
*
* Returns the RCODE. See fw_send_request() for parameter documentation.
* Unlike fw_send_request(), @data points to the payload of the request or/and
- * to the payload of the response.
+ * to the payload of the response. DMA mapping restrictions apply to outbound
+ * request payloads of >= 8 bytes but not to inbound response payloads.
*/
int fw_run_transaction(struct fw_card *card, int tcode, int destination_id,
int generation, int speed, unsigned long long offset,
diff --git a/drivers/media/dvb/firewire/firedtv-avc.c b/drivers/media/dvb/firewire/firedtv-avc.c
index fc5ccd8..21c52e3 100644
--- a/drivers/media/dvb/firewire/firedtv-avc.c
+++ b/drivers/media/dvb/firewire/firedtv-avc.c
@@ -1320,14 +1320,10 @@
{
int ret;
- mutex_lock(&fdtv->avc_mutex);
-
ret = fdtv_read(fdtv, addr, data);
if (ret < 0)
dev_err(fdtv->device, "CMP: read I/O error\n");
- mutex_unlock(&fdtv->avc_mutex);
-
return ret;
}
@@ -1335,18 +1331,9 @@
{
int ret;
- mutex_lock(&fdtv->avc_mutex);
-
- /* data[] is stack-allocated and should not be DMA-mapped. */
- memcpy(fdtv->avc_data, data, 8);
-
- ret = fdtv_lock(fdtv, addr, fdtv->avc_data);
+ ret = fdtv_lock(fdtv, addr, data);
if (ret < 0)
dev_err(fdtv->device, "CMP: lock I/O error\n");
- else
- memcpy(data, fdtv->avc_data, 8);
-
- mutex_unlock(&fdtv->avc_mutex);
return ret;
}