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.

Link: https://lore.kernel.org/r/20240912133038.238786-3-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>

diff --git a/drivers/firewire/core-iso.c b/drivers/firewire/core-iso.c
index 9f41c78878ade206c2060d4f53b8a3a35b55f9f8..f2394f3ed194cd52089bf5a94e3cd48ce675b369 100644 (file)
--- 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 96ae366889e0e27fb51d3440fbea7b993d72bf5a..0ae2c84ecafedb8eb7ecc54ed5edf268a445270e 100644 (file)
--- 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 02ff0363d3ad78e07527c69c97f31818cdb85f59..3a911cfb5ff31a4bd1a31cf984d061b6def53f5b 100644 (file)
--- 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: