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Date:      Wed, 8 Jan 2020 23:03:48 +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: r356525 - head/sys/dev/iicbus/mux
Message-ID:  <202001082303.008N3mvh079557@repo.freebsd.org>
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Author: ian
Date: Wed Jan  8 23:03:47 2020
New Revision: 356525
URL: https://svnweb.freebsd.org/changeset/base/356525

Log:
  Split the code to find and add iicbus children out to its own function.
  Move the decision to take an early exit from that function after adding
  children based on FDT data into the #ifdef FDT block, so that it doesn't
  offend coverity's notion of how the code should be written.  (What's the
  point of compilers optimizing away dead code if static analyzers won't
  let you use the feature in conjuction with an #ifdef block?)
  
  Reported by:	coverity via vangyzen@

Modified:
  head/sys/dev/iicbus/mux/iicmux.c

Modified: head/sys/dev/iicbus/mux/iicmux.c
==============================================================================
--- head/sys/dev/iicbus/mux/iicmux.c	Wed Jan  8 22:59:31 2020	(r356524)
+++ head/sys/dev/iicbus/mux/iicmux.c	Wed Jan  8 23:03:47 2020	(r356525)
@@ -240,36 +240,13 @@ iicmux_add_child(device_t dev, device_t child, int bus
 	return (0);
 }
 
-int
-iicmux_attach(device_t dev, device_t busdev, int numbuses)
+static int
+iicmux_attach_children(struct iicmux_softc *sc)
 {
-	struct iicmux_softc *sc = device_get_softc(dev);
-	int i, numadded;
-
-	if (numbuses >= IICMUX_MAX_BUSES) {
-		device_printf(dev, "iicmux_attach: numbuses %d > max %d\n",
-		    numbuses, IICMUX_MAX_BUSES);
-		return (EINVAL);
-	}
-
-	sc->dev = dev;
-	sc->busdev = busdev;
-	sc->maxbus = -1;
-	sc->numbuses = numbuses;
-
-	SYSCTL_ADD_UINT(device_get_sysctl_ctx(sc->dev), 
-	    SYSCTL_CHILDREN(device_get_sysctl_tree(sc->dev)), OID_AUTO,
-	    "debugmux", CTLFLAG_RWTUN, &sc->debugmux, 0, "debug mux operations");
-
-        /*
-         * Add children...
-         */
-	numadded = 0;
-
+	int i;
 #ifdef FDT
 	phandle_t child, node, parent;
-	pcell_t reg;
-	int idx;
+	pcell_t idx;
 
 	/*
 	 * Find our FDT node.  Child nodes within our node will become our
@@ -292,14 +269,13 @@ iicmux_attach(device_t dev, device_t busdev, int numbu
 	 * Attach the children represented in the device tree.
 	 */
 	for (child = OF_child(parent); child != 0; child = OF_peer(child)) {
-		if (OF_getencprop(child, "reg", &reg, sizeof(reg)) == -1) {
-			device_printf(dev,
+		if (OF_getencprop(child, "reg", &idx, sizeof(idx)) == -1) {
+			device_printf(sc->dev,
 			    "child bus missing required 'reg' property\n");
 			continue;
 		}
-		idx = (int)reg;
 		if (idx >= sc->numbuses) {
-			device_printf(dev,
+			device_printf(sc->dev,
 			    "child bus 'reg' property %d exceeds the number "
 			    "of buses supported by the device (%d)\n",
 			    idx, sc->numbuses);
@@ -309,21 +285,48 @@ iicmux_attach(device_t dev, device_t busdev, int numbu
 		sc->childnodes[idx] = child;
 		if (sc->maxbus < idx)
 			sc->maxbus = idx;
-		++numadded;
 	}
+
+	/* If we configured anything using FDT data, we're done. */
+	if (sc->maxbus >= 0)
+		return (0);
 #endif /* FDT */
 
 	/*
-	 * If we configured anything using FDT data, we're done.  Otherwise add
-	 * an iicbus child for every downstream bus supported by the mux chip.
+	 * If we make it to here, we didn't add any children based on FDT data.
+	 * Add an iicbus child for every downstream bus supported by the mux.
 	 */
-	if (numadded > 0)
-		return (0);
-
 	for (i = 0; i < sc->numbuses; ++i) {
 		sc->childdevs[i] = device_add_child(sc->dev, "iicbus", -1);
+		sc->maxbus = i;
 	}
-	sc->maxbus = sc->numbuses - 1;
+
+	return (0);
+}
+
+int
+iicmux_attach(device_t dev, device_t busdev, int numbuses)
+{
+	struct iicmux_softc *sc = device_get_softc(dev);
+	int err;
+
+	if (numbuses >= IICMUX_MAX_BUSES) {
+		device_printf(dev, "iicmux_attach: numbuses %d > max %d\n",
+		    numbuses, IICMUX_MAX_BUSES);
+		return (EINVAL);
+	}
+
+	sc->dev = dev;
+	sc->busdev = busdev;
+	sc->maxbus = -1;
+	sc->numbuses = numbuses;
+
+	if ((err = iicmux_attach_children(sc)) != 0)
+		return (err);
+
+	SYSCTL_ADD_UINT(device_get_sysctl_ctx(sc->dev), 
+	    SYSCTL_CHILDREN(device_get_sysctl_tree(sc->dev)), OID_AUTO,
+	    "debugmux", CTLFLAG_RWTUN, &sc->debugmux, 0, "debug mux operations");
 
 	return (0);
 }

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