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Message-ID: <20240912133038.238786-3-o-takashi@sakamocchi.jp>
Date: Thu, 12 Sep 2024 22:30:35 +0900
From: Takashi Sakamoto <o-takashi@...amocchi.jp>
To: linux1394-devel@...ts.sourceforge.net
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH 2/5] Revert "firewire: core: move workqueue handler from 1394 OHCI driver to core function"
This reverts commit 767bfb9ef27ebf760290d9f8bc303828b018c312. It appears
that the call of ohci_flush_iso_completions() in the work item scheduled
by hardIRQ of 1394 OHCI for any isochronous context changes the timing to
queue events in the view of user space application.
Signed-off-by: Takashi Sakamoto <o-takashi@...amocchi.jp>
---
drivers/firewire/core-iso.c | 26 ++++++++++++---------
drivers/firewire/core.h | 5 +++++
drivers/firewire/ohci.c | 45 +++++++++++++++++++++++++++++++++++--
3 files changed, 64 insertions(+), 12 deletions(-)
diff --git a/drivers/firewire/core-iso.c b/drivers/firewire/core-iso.c
index 9f41c78878ad..f2394f3ed194 100644
--- a/drivers/firewire/core-iso.c
+++ b/drivers/firewire/core-iso.c
@@ -131,13 +131,6 @@ size_t fw_iso_buffer_lookup(struct fw_iso_buffer *buffer, dma_addr_t completed)
return 0;
}
-static void flush_completions_work(struct work_struct *work)
-{
- struct fw_iso_context *ctx = container_of(work, struct fw_iso_context, work);
-
- fw_iso_context_flush_completions(ctx);
-}
-
struct fw_iso_context *fw_iso_context_create(struct fw_card *card,
int type, int channel, int speed, size_t header_size,
fw_iso_callback_t callback, void *callback_data)
@@ -156,7 +149,6 @@ struct fw_iso_context *fw_iso_context_create(struct fw_card *card,
ctx->header_size = header_size;
ctx->callback.sc = callback;
ctx->callback_data = callback_data;
- INIT_WORK(&ctx->work, flush_completions_work);
trace_isoc_outbound_allocate(ctx, channel, speed);
trace_isoc_inbound_single_allocate(ctx, channel, header_size);
@@ -226,15 +218,29 @@ 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. May sleep due to disable_work_sync().
*/
int fw_iso_context_flush_completions(struct fw_iso_context *ctx)
{
+ int err;
+
trace_isoc_outbound_flush_completions(ctx);
trace_isoc_inbound_single_flush_completions(ctx);
trace_isoc_inbound_multiple_flush_completions(ctx);
- return ctx->card->driver->flush_iso_completions(ctx);
+ might_sleep();
+
+ // Avoid dead lock due to programming mistake.
+ if (WARN_ON_ONCE(current_work() == &ctx->work))
+ return 0;
+
+ disable_work_sync(&ctx->work);
+
+ err = ctx->card->driver->flush_iso_completions(ctx);
+
+ enable_work(&ctx->work);
+
+ return err;
}
EXPORT_SYMBOL(fw_iso_context_flush_completions);
diff --git a/drivers/firewire/core.h b/drivers/firewire/core.h
index 96ae366889e0..0ae2c84ecafe 100644
--- a/drivers/firewire/core.h
+++ b/drivers/firewire/core.h
@@ -159,6 +159,11 @@ int fw_iso_buffer_alloc(struct fw_iso_buffer *buffer, int page_count);
int fw_iso_buffer_map_dma(struct fw_iso_buffer *buffer, struct fw_card *card,
enum dma_data_direction direction);
+static inline void fw_iso_context_init_work(struct fw_iso_context *ctx, work_func_t func)
+{
+ INIT_WORK(&ctx->work, func);
+}
+
/* -topology */
diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c
index 02ff0363d3ad..3a911cfb5ff3 100644
--- a/drivers/firewire/ohci.c
+++ b/drivers/firewire/ohci.c
@@ -1182,6 +1182,47 @@ static void context_tasklet(unsigned long data)
}
}
+static void ohci_isoc_context_work(struct work_struct *work)
+{
+ struct fw_iso_context *base = container_of(work, struct fw_iso_context, work);
+ struct iso_context *isoc_ctx = container_of(base, struct iso_context, base);
+ struct context *ctx = &isoc_ctx->context;
+ struct descriptor *d, *last;
+ u32 address;
+ int z;
+ struct descriptor_buffer *desc;
+
+ desc = list_entry(ctx->buffer_list.next, struct descriptor_buffer, list);
+ last = ctx->last;
+ while (last->branch_address != 0) {
+ struct descriptor_buffer *old_desc = desc;
+
+ address = le32_to_cpu(last->branch_address);
+ z = address & 0xf;
+ address &= ~0xf;
+ ctx->current_bus = address;
+
+ // If the branch address points to a buffer outside of the current buffer, advance
+ // to the next buffer.
+ if (address < desc->buffer_bus || address >= desc->buffer_bus + desc->used)
+ desc = list_entry(desc->list.next, struct descriptor_buffer, list);
+ d = desc->buffer + (address - desc->buffer_bus) / sizeof(*d);
+ last = find_branch_descriptor(d, z);
+
+ if (!ctx->callback(ctx, d, last))
+ break;
+
+ if (old_desc != desc) {
+ // If we've advanced to the next buffer, move the previous buffer to the
+ // free list.
+ old_desc->used = 0;
+ guard(spinlock_irqsave)(&ctx->ohci->lock);
+ list_move_tail(&old_desc->list, &ctx->buffer_list);
+ }
+ ctx->last = last;
+ }
+}
+
/*
* Allocate a new buffer and add it to the list of free buffers for this
* context. Must be called with ohci->lock held.
@@ -3128,6 +3169,7 @@ static struct fw_iso_context *ohci_allocate_iso_context(struct fw_card *card,
ret = context_init(&ctx->context, ohci, regs, callback);
if (ret < 0)
goto out_with_header;
+ fw_iso_context_init_work(&ctx->base, ohci_isoc_context_work);
if (type == FW_ISO_CONTEXT_RECEIVE_MULTICHANNEL) {
set_multichannel_mask(ohci, 0);
@@ -3582,8 +3624,7 @@ static int ohci_flush_iso_completions(struct fw_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);
+ ohci_isoc_context_work(&base->work);
switch (base->type) {
case FW_ISO_CONTEXT_TRANSMIT:
--
2.43.0
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