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Message-ID: <20250614113449.388758-4-o-takashi@sakamocchi.jp>
Date: Sat, 14 Jun 2025 20:34:49 +0900
From: Takashi Sakamoto <o-takashi@...amocchi.jp>
To: linux1394-devel@...ts.sourceforge.net
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH 3/3] firewire: ohci: use workqueue to handle events of AT request/response contexts
This commit adds a work item to handle events of 1394 OHCI AT
request/response contexts, and queues the item to the specific
workqueue. The call of struct fw_packet.callbaqck() is done in the
workqueue when receiving acknowledgement to the asynchronous packet
transferred to remote node.
Signed-off-by: Takashi Sakamoto <o-takashi@...amocchi.jp>
---
drivers/firewire/net.c | 4 ++--
drivers/firewire/ohci.c | 40 ++++++++++++++++++++++++----------------
include/linux/firewire.h | 11 +++++++++--
3 files changed, 35 insertions(+), 20 deletions(-)
diff --git a/drivers/firewire/net.c b/drivers/firewire/net.c
index 1bf0e15c1540..6d6446713539 100644
--- a/drivers/firewire/net.c
+++ b/drivers/firewire/net.c
@@ -1007,7 +1007,7 @@ static int fwnet_send_packet(struct fwnet_packet_task *ptask)
spin_lock_irqsave(&dev->lock, flags);
- /* If the AT tasklet already ran, we may be last user. */
+ /* If the AT work item already ran, we may be last user. */
free = (ptask->outstanding_pkts == 0 && !ptask->enqueued);
if (!free)
ptask->enqueued = true;
@@ -1026,7 +1026,7 @@ static int fwnet_send_packet(struct fwnet_packet_task *ptask)
spin_lock_irqsave(&dev->lock, flags);
- /* If the AT tasklet already ran, we may be last user. */
+ /* If the AT work item already ran, we may be last user. */
free = (ptask->outstanding_pkts == 0 && !ptask->enqueued);
if (!free)
ptask->enqueued = true;
diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c
index 68317b5a64a7..a81a876819d0 100644
--- a/drivers/firewire/ohci.c
+++ b/drivers/firewire/ohci.c
@@ -158,7 +158,7 @@ struct context {
descriptor_callback_t callback;
- struct tasklet_struct tasklet;
+ struct work_struct work;
};
struct iso_context {
@@ -1176,9 +1176,9 @@ static void context_retire_descriptors(struct context *ctx)
}
}
-static void context_tasklet(unsigned long data)
+static void ohci_at_context_work(struct work_struct *work)
{
- struct context *ctx = (struct context *) data;
+ struct context *ctx = from_work(ctx, work, work);
context_retire_descriptors(ctx);
}
@@ -1243,7 +1243,6 @@ static int context_init(struct context *ctx, struct fw_ohci *ohci,
ctx->buffer_tail = list_entry(ctx->buffer_list.next,
struct descriptor_buffer, list);
- tasklet_init(&ctx->tasklet, context_tasklet, (unsigned long)ctx);
ctx->callback = callback;
/*
@@ -1524,13 +1523,17 @@ static int at_context_queue_packet(struct context *ctx,
static void at_context_flush(struct context *ctx)
{
- tasklet_disable(&ctx->tasklet);
+ // Avoid dead lock due to programming mistake.
+ if (WARN_ON_ONCE(current_work() == &ctx->work))
+ return;
+
+ disable_work_sync(&ctx->work);
- ctx->flushing = true;
- context_tasklet((unsigned long)ctx);
- ctx->flushing = false;
+ WRITE_ONCE(ctx->flushing, true);
+ ohci_at_context_work(&ctx->work);
+ WRITE_ONCE(ctx->flushing, false);
- tasklet_enable(&ctx->tasklet);
+ enable_work(&ctx->work);
}
static int handle_at_packet(struct context *context,
@@ -1542,7 +1545,7 @@ static int handle_at_packet(struct context *context,
struct fw_ohci *ohci = context->ohci;
int evt;
- if (last->transfer_status == 0 && !context->flushing)
+ if (last->transfer_status == 0 && !READ_ONCE(context->flushing))
/* This descriptor isn't done yet, stop iteration. */
return 0;
@@ -1576,7 +1579,7 @@ static int handle_at_packet(struct context *context,
break;
case OHCI1394_evt_missing_ack:
- if (context->flushing)
+ if (READ_ONCE(context->flushing))
packet->ack = RCODE_GENERATION;
else {
/*
@@ -1598,7 +1601,7 @@ static int handle_at_packet(struct context *context,
break;
case OHCI1394_evt_no_status:
- if (context->flushing) {
+ if (READ_ONCE(context->flushing)) {
packet->ack = RCODE_GENERATION;
break;
}
@@ -2239,10 +2242,10 @@ static irqreturn_t irq_handler(int irq, void *data)
queue_work(ohci->card.async_wq, &ohci->ar_response_ctx.work);
if (event & OHCI1394_reqTxComplete)
- tasklet_schedule(&ohci->at_request_ctx.tasklet);
+ queue_work(ohci->card.async_wq, &ohci->at_request_ctx.work);
if (event & OHCI1394_respTxComplete)
- tasklet_schedule(&ohci->at_response_ctx.tasklet);
+ queue_work(ohci->card.async_wq, &ohci->at_response_ctx.work);
if (event & OHCI1394_isochRx) {
iso_event = reg_read(ohci, OHCI1394_IsoRecvIntEventClear);
@@ -2684,7 +2687,10 @@ static int ohci_cancel_packet(struct fw_card *card, struct fw_packet *packet)
struct driver_data *driver_data = packet->driver_data;
int ret = -ENOENT;
- tasklet_disable_in_atomic(&ctx->tasklet);
+ // Avoid dead lock due to programming mistake.
+ if (WARN_ON_ONCE(current_work() == &ctx->work))
+ return 0;
+ disable_work_sync(&ctx->work);
if (packet->ack != 0)
goto out;
@@ -2703,7 +2709,7 @@ static int ohci_cancel_packet(struct fw_card *card, struct fw_packet *packet)
packet->callback(packet, &ohci->card, packet->ack);
ret = 0;
out:
- tasklet_enable(&ctx->tasklet);
+ enable_work(&ctx->work);
return ret;
}
@@ -3765,11 +3771,13 @@ static int pci_probe(struct pci_dev *dev,
OHCI1394_AsReqTrContextControlSet, handle_at_packet);
if (err < 0)
return err;
+ INIT_WORK(&ohci->at_request_ctx.work, ohci_at_context_work);
err = context_init(&ohci->at_response_ctx, ohci,
OHCI1394_AsRspTrContextControlSet, handle_at_packet);
if (err < 0)
return err;
+ INIT_WORK(&ohci->at_response_ctx.work, ohci_at_context_work);
reg_write(ohci, OHCI1394_IsoRecvIntMaskSet, ~0);
ohci->ir_context_channels = ~0ULL;
diff --git a/include/linux/firewire.h b/include/linux/firewire.h
index c55b8e30e700..cceb70415ed2 100644
--- a/include/linux/firewire.h
+++ b/include/linux/firewire.h
@@ -308,8 +308,7 @@ struct fw_packet {
* For successful transmission, the status code is the ack received
* from the destination. Otherwise it is one of the juju-specific
* rcodes: RCODE_SEND_ERROR, _CANCELLED, _BUSY, _GENERATION, _NO_ACK.
- * The callback can be called from tasklet context and thus
- * must never block.
+ * The callback can be called from workqueue and thus must never block.
*/
fw_packet_callback_t callback;
int ack;
@@ -382,6 +381,10 @@ void __fw_send_request(struct fw_card *card, struct fw_transaction *t, int tcode
*
* A variation of __fw_send_request() to generate callback for response subaction without time
* stamp.
+ *
+ * The callback is invoked in the workqueue context in most cases. However, if an error is detected
+ * before queueing or the destination address refers to the local node, it is invoked in the
+ * current context instead.
*/
static inline void fw_send_request(struct fw_card *card, struct fw_transaction *t, int tcode,
int destination_id, int generation, int speed,
@@ -411,6 +414,10 @@ static inline void fw_send_request(struct fw_card *card, struct fw_transaction *
* @callback_data: data to be passed to the transaction completion callback
*
* A variation of __fw_send_request() to generate callback for response subaction with time stamp.
+ *
+ * The callback is invoked in the workqueue context in most cases. However, if an error is detected
+ * before queueing or the destination address refers to the local node, it is invoked in the current
+ * context instead.
*/
static inline void fw_send_request_with_tstamp(struct fw_card *card, struct fw_transaction *t,
int tcode, int destination_id, int generation, int speed, unsigned long long offset,
--
2.48.1
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