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Commit f30e6d3e authored by Stefan Richter's avatar Stefan Richter
Browse files

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 da28947e
"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: default avatarStefan Richter <stefanr@s5r6.in-berlin.de>
Acked-by: default avatarClemens Ladisch <clemens@ladisch.de>
parent 020abf03

drivers/firewire/core-card.c

+8 −8
Original line number Diff line number Diff line
@@ -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;

	}

drivers/firewire/core-cdev.c

+1 −3
Original line number Diff line number Diff line
@@ -141,7 +141,6 @@ struct iso_resource { 
	int generation;

	u64 channels;

	s32 bandwidth;

	__be32 transaction_data[2];

	struct iso_resource_event *e_alloc, *e_dealloc;

};
@@ -1229,8 +1228,7 @@ static void iso_resource_work(struct work_struct *work) 
			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

drivers/firewire/core-iso.c

+11 −10
Original line number Diff line number Diff line
@@ -196,9 +196,10 @@ EXPORT_SYMBOL(fw_iso_context_stop); 
 */



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_bandwidth(struct fw_card *card, int irm_id, int generation, 
}



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 int manage_channel(struct fw_card *card, int irm_id, int generation, 
}



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 @@ static void deallocate_channel(struct fw_card *card, int irm_id, 
	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 @@ static void deallocate_channel(struct fw_card *card, int irm_id, 
 */

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 @@ void fw_iso_resource_manage(struct fw_card *card, int generation, 
	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 @@ void fw_iso_resource_manage(struct fw_card *card, int generation, 
	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;

	}

}

drivers/firewire/core-transaction.c

+4 −3
Original line number Diff line number Diff line
@@ -326,8 +326,8 @@ static int allocate_tlabel(struct fw_card *card) 
 * 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 @@ static void transaction_callback(struct fw_card *card, int rcode, 
 *

 * 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,

drivers/media/dvb/firewire/firedtv-avc.c

+1 −14
Original line number Diff line number Diff line
@@ -1320,14 +1320,10 @@ static int cmp_read(struct firedtv *fdtv, u64 addr, __be32 *data) 
{

	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 @@ static int cmp_lock(struct firedtv *fdtv, u64 addr, __be32 data[]) 
{

	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;

}