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Date:      Sat, 6 Sep 2014 18:43:17 +0000 (UTC)
From:      Ian Lepore <ian@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r271202 - head/sys/dev/ofw
Message-ID:  <201409061843.s86IhHMJ054856@svn.freebsd.org>
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Author: ian
Date: Sat Sep  6 18:43:17 2014
New Revision: 271202
URL: http://svnweb.freebsd.org/changeset/base/271202

Log:
  When registering an association between a device and an xref phandle, create
  an entry in the xref list if one doesn't already exist for the given handle.
  
  On a system that uses phandle properties, the init-time scan of the tree
  which builds the xref list will pre-create entries for every xref handle
  that exists in the data.  On systems where the xref and node handles are
  synonymous there is no phandle property in referenced nodes, and the xref
  list will initialize to an empty state.  In the latter case, we still need
  to be able to associate a device_t with an xref handle, so we create list
  entries on the fly as needed.  Since the node and xref handles are
  synonymous, we have all the info needed to create a list entry at device
  registration time.
  
  The downside to this change is that it basically allows on the fly creation
  of xref handles as synonyms of node handles, and the association of a
  device_t with them.  Whether this is a bug or a feature is in the eye of
  the beholder, I guess.

Modified:
  head/sys/dev/ofw/openfirm.c

Modified: head/sys/dev/ofw/openfirm.c
==============================================================================
--- head/sys/dev/ofw/openfirm.c	Sat Sep  6 18:20:50 2014	(r271201)
+++ head/sys/dev/ofw/openfirm.c	Sat Sep  6 18:43:17 2014	(r271202)
@@ -62,7 +62,10 @@ __FBSDID("$FreeBSD$");
 
 #include <sys/param.h>
 #include <sys/kernel.h>
+#include <sys/lock.h>
 #include <sys/malloc.h>
+#include <sys/mutex.h>
+#include <sys/queue.h>
 #include <sys/systm.h>
 #include <sys/endian.h>
 
@@ -92,6 +95,7 @@ struct xrefinfo {
 };
 
 static SLIST_HEAD(, xrefinfo) xreflist = SLIST_HEAD_INITIALIZER(xreflist);
+static struct mtx xreflist_lock;
 static boolean_t xref_init_done;
 
 #define	FIND_BY_XREF	0
@@ -138,6 +142,12 @@ static void
 xrefinfo_init(void *unsed)
 {
 
+	/*
+	 * There is no locking during this init because it runs much earlier
+	 * than any of the clients/consumers of the xref list data, but we do
+	 * initialize the mutex that will be used for access later.
+	 */
+	mtx_init(&xreflist_lock, "OF xreflist lock", NULL, MTX_DEF);
 	xrefinfo_create(OF_peer(0));
 	xref_init_done = true;
 }
@@ -146,17 +156,35 @@ SYSINIT(xrefinfo, SI_SUB_KMEM, SI_ORDER_
 static struct xrefinfo *
 xrefinfo_find(phandle_t phandle, int find_by)
 {
-	struct xrefinfo * xi;
+	struct xrefinfo *rv, *xi;
 
+	rv = NULL;
+	mtx_lock(&xreflist_lock);
 	SLIST_FOREACH(xi, &xreflist, next_entry) {
-		if (find_by == FIND_BY_XREF && phandle == xi->xref)
-			return (xi);
-		else if (find_by == FIND_BY_NODE && phandle == xi->node)
-			return (xi);
-		else if (find_by == FIND_BY_DEV && phandle == (uintptr_t)xi->dev)
-			return (xi);
+		if ((find_by == FIND_BY_XREF && phandle == xi->xref) ||
+		    (find_by == FIND_BY_NODE && phandle == xi->node) ||
+		    (find_by == FIND_BY_DEV && phandle == (uintptr_t)xi->dev)) {
+			rv = xi;
+			break;
+		}
 	}
-	return (NULL);
+	mtx_unlock(&xreflist_lock);
+	return (rv);
+}
+
+static struct xrefinfo *
+xrefinfo_add(phandle_t node, phandle_t xref, device_t dev)
+{
+	struct xrefinfo *xi;
+
+	xi = malloc(sizeof(*xi), M_OFWPROP, M_WAITOK);
+	xi->node = node;
+	xi->xref = xref;
+	xi->dev  = dev;
+	mtx_lock(&xreflist_lock);
+	SLIST_INSERT_HEAD(&xreflist, xi, next_entry);
+	mtx_unlock(&xreflist_lock);
+	return (xi);
 }
 
 /*
@@ -605,10 +633,17 @@ OF_device_register_xref(phandle_t xref, 
 {
 	struct xrefinfo *xi;
 
+	/*
+	 * If the given xref handle doesn't already exist in the list then we
+	 * add a list entry.  In theory this can only happen on a system where
+	 * nodes don't contain phandle properties and xref and node handles are
+	 * synonymous, so the xref handle is added as the node handle as well.
+	 */
 	if (xref_init_done) {
 		if ((xi = xrefinfo_find(xref, FIND_BY_XREF)) == NULL)
-			return (ENXIO);
-		xi->dev = dev;
+			xrefinfo_add(xref, xref, dev);
+		else 
+			xi->dev = dev;
 		return (0);
 	}
 	panic("Attempt to register device before xreflist_init");

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