2 files changed, 18 insertions, 7 deletions

diff --git a/drivers/firewire/core-transaction.c b/drivers/firewire/core-transaction.c
index d39cfa45817a..28a94c7ec6e5 100644
--- a/drivers/firewire/core-transaction.c
+++ b/drivers/firewire/core-transaction.c
@@ -519,7 +519,7 @@ static struct fw_address_handler *lookup_enclosing_address_handler(
         return NULL;
 }
 
-static DEFINE_SPINLOCK(address_handler_lock);
+static DEFINE_SPINLOCK(address_handler_list_lock);
 static LIST_HEAD(address_handler_list);
 
 const struct fw_address_region fw_high_memory_region =
@@ -556,6 +556,7 @@ static bool is_in_fcp_region(u64 offset, size_t length)
  * the specified callback is invoked.  The parameters passed to the callback
  * give the details of the particular request.
  *
+ * To be called in process context.
  * Return value:  0 on success, non-zero otherwise.
  *
  * The start offset of the handler's address region is determined by
@@ -576,7 +577,7 @@ int fw_core_add_address_handler(struct fw_address_handler *handler,
             handler->length == 0)
                 return -EINVAL;
 
-        spin_lock_bh(&address_handler_lock);
+        spin_lock(&address_handler_list_lock);
 
         handler->offset = region->start;
         while (handler->offset + handler->length <= region->end) {
@@ -595,7 +596,7 @@ int fw_core_add_address_handler(struct fw_address_handler *handler,
                 }
         }
 
-        spin_unlock_bh(&address_handler_lock);
+        spin_unlock(&address_handler_list_lock);
 
         return ret;
 }
@@ -604,14 +605,16 @@ EXPORT_SYMBOL(fw_core_add_address_handler);
 /**
  * fw_core_remove_address_handler() - unregister an address handler
  *
+ * To be called in process context.
+ *
  * When fw_core_remove_address_handler() returns, @handler->callback() is
  * guaranteed to not run on any CPU anymore.
  */
 void fw_core_remove_address_handler(struct fw_address_handler *handler)
 {
-        spin_lock_bh(&address_handler_lock);
+        spin_lock(&address_handler_list_lock);
         list_del_rcu(&handler->link);
-        spin_unlock_bh(&address_handler_lock);
+        spin_unlock(&address_handler_list_lock);
         synchronize_rcu();
 }
 EXPORT_SYMBOL(fw_core_remove_address_handler);
diff --git a/include/linux/firewire.h b/include/linux/firewire.h
index db04ec5121cb..191501afd7fb 100644
--- a/include/linux/firewire.h
+++ b/include/linux/firewire.h
@@ -265,8 +265,16 @@ typedef void (*fw_transaction_callback_t)(struct fw_card *card, int rcode,
                                           void *data, size_t length,
                                           void *callback_data);
 /*
- * Important note:  Except for the FCP registers, the callback must guarantee
- * that either fw_send_response() or kfree() is called on the @request.
+ * This callback handles an inbound request subaction.  It is called in
+ * RCU read-side context, therefore must not sleep.
+ *
+ * The callback should not initiate outbound request subactions directly.
+ * Otherwise there is a danger of recursion of inbound and outbound
+ * transactions from and to the local node.
+ *
+ * The callback is responsible that either fw_send_response() or kfree()
+ * is called on the @request, except for FCP registers for which the core
+ * takes care of that.
  */
 typedef void (*fw_address_callback_t)(struct fw_card *card,
                                       struct fw_request *request,