1 files changed, 10 insertions, 2 deletions

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,