[RFC PATCH v4 1/5] libfcoe: Save some memory and optimize name lookups

[Robert Love <robert.w.love@intel.com>]

Instead of creating a structure with an enum and a pointer
to a string, simply allocate an array of strings and use
the enum values for the indicies.

This means that we do not need to iterate through the list
of entries when looking up a string name by its enum key.

This will also help with a latter patch that will add
more fcoe_sysfs attributes that will also use the
fcoe_enum_name_search macro. One attribute will also do
a reverse lookup which requires less code when the
enum-to-string mappings are organized as this patch makes
them to be.

Signed-off-by: Robert Love <robert.w.love@intel.com>
---
 drivers/scsi/fcoe/fcoe_sysfs.c |   44 +++++++++++++++-------------------------
 1 file changed, 16 insertions(+), 28 deletions(-)

diff --git a/drivers/scsi/fcoe/fcoe_sysfs.c b/drivers/scsi/fcoe/fcoe_sysfs.c
index 5e75168..5a74a47 100644
--- a/drivers/scsi/fcoe/fcoe_sysfs.c
+++ b/drivers/scsi/fcoe/fcoe_sysfs.c
@@ -210,25 +210,23 @@ static ssize_t show_fcoe_fcf_device_##field(struct device *dev,	\
 #define fcoe_enum_name_search(title, table_type, table)			\
 static const char *get_fcoe_##title##_name(enum table_type table_key)	\
 {									\
-	int i;								\
-	char *name = NULL;						\
-									\
-	for (i = 0; i < ARRAY_SIZE(table); i++) {			\
-		if (table[i].value == table_key) {			\
-			name = table[i].name;				\
-			break;						\
-		}							\
-	}								\
-	return name;							\
+	if (table_key >= ARRAY_SIZE(table))				\
+		return NULL;						\
+	return table[table_key];					\
 }
 
-static struct {
-	enum fcf_state value;
-	char           *name;
-} fcf_state_names[] = {
-	{ FCOE_FCF_STATE_UNKNOWN,      "Unknown" },
-	{ FCOE_FCF_STATE_DISCONNECTED, "Disconnected" },
-	{ FCOE_FCF_STATE_CONNECTED,    "Connected" },
+static char *fip_conn_type_names[] = {
+	[ FIP_CONN_TYPE_UNKNOWN ] = "Unknown",
+        [ FIP_CONN_TYPE_FABRIC ]  = "Fabric",
+	[ FIP_CONN_TYPE_VN2VN ]   = "VN2VN",
+};
+fcoe_enum_name_search(ctlr_mode, fip_conn_type, fip_conn_type_names)
+#define FCOE_CTLR_MODE_MAX_NAMELEN 50
+
+static char *fcf_state_names[] = {
+	[ FCOE_FCF_STATE_UNKNOWN ]      = "Unknown",
+	[ FCOE_FCF_STATE_DISCONNECTED ] = "Disconnected",
+	[ FCOE_FCF_STATE_CONNECTED ]    = "Connected",
 };
 fcoe_enum_name_search(fcf_state, fcf_state, fcf_state_names)
 #define FCOE_FCF_STATE_MAX_NAMELEN 50
@@ -246,17 +244,7 @@ static ssize_t show_fcf_state(struct device *dev,
 }
 static FCOE_DEVICE_ATTR(fcf, state, S_IRUGO, show_fcf_state, NULL);
 
-static struct {
-	enum fip_conn_type value;
-	char               *name;
-} fip_conn_type_names[] = {
-	{ FIP_CONN_TYPE_UNKNOWN, "Unknown" },
-	{ FIP_CONN_TYPE_FABRIC, "Fabric" },
-	{ FIP_CONN_TYPE_VN2VN, "VN2VN" },
-};
-fcoe_enum_name_search(ctlr_mode, fip_conn_type, fip_conn_type_names)
-#define FCOE_CTLR_MODE_MAX_NAMELEN 50
-
+#define FCOE_MAX_MODENAME_LEN 20
 static ssize_t show_ctlr_mode(struct device *dev,
 			      struct device_attribute *attr,
 			      char *buf)