Commit f877f1d8 authored by Takashi Sakamoto's avatar Takashi Sakamoto
Browse files

firewire: core: use mutex to coordinate concurrent calls to flush completions 

In current implementation, test_and_set_bit_lock() is used to mediate
concurrent calls of ohci_flush_iso_completions(). However, the ad-hoc
usage of atomic operations is not preferable.

This commit uses mutex_trylock() as the similar operations. The core
function is responsible for the mediation, instead of 1394 OHCI driver.

Link: https://lore.kernel.org/r/20240909140018.65289-3-o-takashi@sakamocchi.jp


Signed-off-by: default avatarTakashi Sakamoto <o-takashi@sakamocchi.jp>
parent e97fb38f

drivers/firewire/core-iso.c

+9 −2
Original line number Diff line number Diff line
@@ -157,6 +157,7 @@ struct fw_iso_context *fw_iso_context_create(struct fw_card *card, 
	ctx->callback.sc = callback;

	ctx->callback_data = callback_data;

	INIT_WORK(&ctx->work, flush_completions_work);

	mutex_init(&ctx->flushing_completions_mutex);



	trace_isoc_outbound_allocate(ctx, channel, speed);

	trace_isoc_inbound_single_allocate(ctx, channel, header_size);
@@ -173,6 +174,8 @@ void fw_iso_context_destroy(struct fw_iso_context *ctx) 
	trace_isoc_inbound_multiple_destroy(ctx);



	ctx->card->driver->free_iso_context(ctx);



	mutex_destroy(&ctx->flushing_completions_mutex);

}

EXPORT_SYMBOL(fw_iso_context_destroy);
@@ -226,7 +229,7 @@ EXPORT_SYMBOL(fw_iso_context_queue_flush); 
 * to process the context asynchronously, fw_iso_context_schedule_flush_completions() is available

 * instead.

 *

 * Context: Process context.

 * Context: Process context due to mutex_trylock().

 */

int fw_iso_context_flush_completions(struct fw_iso_context *ctx)

{
@@ -234,8 +237,12 @@ int fw_iso_context_flush_completions(struct fw_iso_context *ctx) 
	trace_isoc_inbound_single_flush_completions(ctx);

	trace_isoc_inbound_multiple_flush_completions(ctx);



	scoped_cond_guard(mutex_try, /* nothing to do */, &ctx->flushing_completions_mutex) {

		return ctx->card->driver->flush_iso_completions(ctx);

	}



	return 0;

}

EXPORT_SYMBOL(fw_iso_context_flush_completions);



int fw_iso_context_stop(struct fw_iso_context *ctx)

drivers/firewire/ohci.c

+14 −23
Original line number Diff line number Diff line
@@ -166,7 +166,6 @@ struct iso_context { 
	struct context context;

	void *header;

	size_t header_length;

	unsigned long flushing_completions;

	u32 mc_buffer_bus;

	u16 mc_completed;

	u16 last_timestamp;
@@ -3579,9 +3578,7 @@ static void ohci_flush_queue_iso(struct fw_iso_context *base) 
static int ohci_flush_iso_completions(struct fw_iso_context *base)

{

	struct iso_context *ctx = container_of(base, struct iso_context, base);

	int ret = 0;



	if (!test_and_set_bit_lock(0, &ctx->flushing_completions)) {

	// Note that tasklet softIRQ is not used to process isochronous context anymore.

	context_tasklet((unsigned long)&ctx->context);
@@ -3590,20 +3587,14 @@ static int ohci_flush_iso_completions(struct fw_iso_context *base) 
	case FW_ISO_CONTEXT_RECEIVE:

		if (ctx->header_length != 0)

			flush_iso_completions(ctx, FW_ISO_CONTEXT_COMPLETIONS_CAUSE_FLUSH);

			break;

		return 0;

	case FW_ISO_CONTEXT_RECEIVE_MULTICHANNEL:

		if (ctx->mc_completed != 0)

			flush_ir_buffer_fill(ctx);

			break;

		return 0;

	default:

			ret = -ENOSYS;

		}



		clear_bit_unlock(0, &ctx->flushing_completions);

		smp_mb__after_atomic();

		return -ENOSYS;

	}



	return ret;

}



static const struct fw_card_driver ohci_driver = {

include/linux/firewire.h

+1 −0
Original line number Diff line number Diff line
@@ -512,6 +512,7 @@ union fw_iso_callback { 
struct fw_iso_context {

	struct fw_card *card;

	struct work_struct work;

	struct mutex flushing_completions_mutex;

	int type;

	int channel;

	int speed;