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

This reverts commit d9605d67562505e27dcc0f71af418118d3db91e5, since this
commit is on the following reverted changes.

Link: https://lore.kernel.org/r/20240912133038.238786-2-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 1405d2e9cb2cab03687e04dfd4ffae079e529e38..9f41c78878ade206c2060d4f53b8a3a35b55f9f8 100644 (file)
--- a/drivers/firewire/core-iso.c
+++ b/drivers/firewire/core-iso.c
@@ -157,7 +157,6 @@ 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);
@@ -174,8 +173,6 @@ 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);
 
@@ -229,7 +226,7 @@ EXPORT_SYMBOL(fw_iso_context_queue_flush);
  * to process the context asynchronously, fw_iso_context_schedule_flush_completions() is available
  * instead.
  *
- * Context: Process context due to mutex_trylock().
+ * Context: Process context.
  */
 int fw_iso_context_flush_completions(struct fw_iso_context *ctx)
 {
@@ -237,11 +234,7 @@ 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;
+       return ctx->card->driver->flush_iso_completions(ctx);
 }
 EXPORT_SYMBOL(fw_iso_context_flush_completions);
 

diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c
index b182998a77f4ce55884d060aa079aa10a661362d..02ff0363d3ad78e07527c69c97f31818cdb85f59 100644 (file)
--- a/drivers/firewire/ohci.c
+++ b/drivers/firewire/ohci.c
@@ -166,6 +166,7 @@ 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;
@@ -3578,23 +3579,31 @@ 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;
 
-       // Note that tasklet softIRQ is not used to process isochronous context anymore.
-       context_tasklet((unsigned long)&ctx->context);
+       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);
 
-       switch (base->type) {
-       case FW_ISO_CONTEXT_TRANSMIT:
-       case FW_ISO_CONTEXT_RECEIVE:
-               if (ctx->header_length != 0)
-                       flush_iso_completions(ctx, FW_ISO_CONTEXT_COMPLETIONS_CAUSE_FLUSH);
-               return 0;
-       case FW_ISO_CONTEXT_RECEIVE_MULTICHANNEL:
-               if (ctx->mc_completed != 0)
-                       flush_ir_buffer_fill(ctx);
-               return 0;
-       default:
-               return -ENOSYS;
+               switch (base->type) {
+               case FW_ISO_CONTEXT_TRANSMIT:
+               case FW_ISO_CONTEXT_RECEIVE:
+                       if (ctx->header_length != 0)
+                               flush_iso_completions(ctx, FW_ISO_CONTEXT_COMPLETIONS_CAUSE_FLUSH);
+                       break;
+               case FW_ISO_CONTEXT_RECEIVE_MULTICHANNEL:
+                       if (ctx->mc_completed != 0)
+                               flush_ir_buffer_fill(ctx);
+                       break;
+               default:
+                       ret = -ENOSYS;
+               }
+
+               clear_bit_unlock(0, &ctx->flushing_completions);
+               smp_mb__after_atomic();
        }
+
+       return ret;
 }
 
 static const struct fw_card_driver ohci_driver = {

diff --git a/include/linux/firewire.h b/include/linux/firewire.h
index 19e8c5f9537c6b24eab241f9951d12991ac2a1a0..f815d12deda0315ff045f1bc58d6ef24f3bad587 100644 (file)
--- a/include/linux/firewire.h
+++ b/include/linux/firewire.h
@@ -512,7 +512,6 @@ 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;