From daa8ed9274d91a157dc049f00792f62c98b0a11a Mon Sep 17 00:00:00 2001
From: Michael Brown <mcb30@ipxe.org>
Date: Wed, 16 Nov 2016 22:22:13 +0000
Subject: [PATCH] [interface] Provide intf_reinit() to reinitialise nullified
 interfaces

Provide an abstraction intf_reinit() to restore the descriptor of a
previously nullified interface.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
---
 src/core/interface.c         |  3 +--
 src/include/ipxe/interface.h | 18 ++++++++++++++++++
 src/net/tcp/httpcore.c       |  5 +----
 3 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/src/core/interface.c b/src/core/interface.c
index ba148c13..948fa5c5 100644
--- a/src/core/interface.c
+++ b/src/core/interface.c
@@ -295,7 +295,6 @@ void intf_shutdown ( struct interface *intf, int rc ) {
  * blocked during shutdown.
  */
 void intf_restart ( struct interface *intf, int rc ) {
-	struct interface_descriptor *desc = intf->desc;
 
 	/* Shut down the interface */
 	intf_shutdown ( intf, rc );
@@ -309,7 +308,7 @@ void intf_restart ( struct interface *intf, int rc ) {
 	 * infinite loop as the intf_close() operations on each side
 	 * of the link call each other recursively.
 	 */
-	intf->desc = desc;
+	intf_reinit ( intf );
 }
 
 /**
diff --git a/src/include/ipxe/interface.h b/src/include/ipxe/interface.h
index a8d82377..ebb1b691 100644
--- a/src/include/ipxe/interface.h
+++ b/src/include/ipxe/interface.h
@@ -123,6 +123,11 @@ struct interface {
 	struct refcnt *refcnt;
 	/** Interface descriptor */
 	struct interface_descriptor *desc;
+	/** Original interface descriptor
+	 *
+	 * Used by intf_reinit().
+	 */
+	struct interface_descriptor *original;
 };
 
 extern void intf_plug ( struct interface *intf, struct interface *dest );
@@ -166,6 +171,7 @@ static inline void intf_init ( struct interface *intf,
 	intf->dest = &null_intf;
 	intf->refcnt = refcnt;
 	intf->desc = desc;
+	intf->original = desc;
 }
 
 /**
@@ -177,6 +183,7 @@ static inline void intf_init ( struct interface *intf,
 		.dest = &null_intf,		\
 		.refcnt = NULL,			\
 		.desc = &(descriptor),		\
+		.original = &(descriptor),	\
 	}
 
 /**
@@ -236,4 +243,15 @@ static inline void intf_init ( struct interface *intf,
  */
 #define INTF_INTF_DBG( intf, dest ) INTF_DBG ( intf ), INTF_DBG ( dest )
 
+/**
+ * Reinitialise an object interface
+ *
+ * @v intf		Object interface
+ */
+static inline void intf_reinit ( struct interface *intf ) {
+
+	/* Restore original interface descriptor */
+	intf->desc = intf->original;
+}
+
 #endif /* _IPXE_INTERFACE_H */
diff --git a/src/net/tcp/httpcore.c b/src/net/tcp/httpcore.c
index b1f74bc4..27cc5065 100644
--- a/src/net/tcp/httpcore.c
+++ b/src/net/tcp/httpcore.c
@@ -787,12 +787,9 @@ static int http_transfer_complete ( struct http_transaction *http ) {
 	/* Restart content decoding interfaces (which may be attached
 	 * to the same object).
 	 */
-	intf_nullify ( &http->content );
-	intf_nullify ( &http->transfer );
+	intf_nullify ( &http->transfer ); /* avoid potential loops */
 	intf_restart ( &http->content, http->response.rc );
 	intf_restart ( &http->transfer, http->response.rc );
-	http->content.desc = &http_content_desc;
-	http->transfer.desc = &http_transfer_desc;
 	intf_plug_plug ( &http->transfer, &http->content );
 	http->len = 0;
 	assert ( http->remaining == 0 );