Fix USB driver matching in devmatch(8).

Multiple drivers can match on the same USB device and the order of loading
decides which driver gets the device. Use the supplied mask value as an
indication of priority, so that vendor specific device drivers are loaded
before more generic ones.

Sponsored by:	Mellanox Technologies

sbin/devmatch/devmatch.c

@@ -54,6 +54,14 @@ static struct option longopts[] = {
 	{ NULL,			0,			NULL,	0 }
 };
 
+#define	DEVMATCH_MAX_HITS 256
+
+static struct match_data {
+	char *descr;
+	int priority;
+} match_data[DEVMATCH_MAX_HITS];
+
+static int hit_index;
 static int all_flag;
 static int dump_flag;
 static char *linker_hints;
@@ -236,6 +244,35 @@ pnpval_as_str(const char *val, const char *pnpinfo)
 	return retval;
 }
 
+static int
+match_data_compare(const void *_pa, const void *_pb)
+{
+	const struct match_data *pa = _pa;
+	const struct match_data *pb = _pb;
+
+	/* biggest value first */
+	if (pa->priority > pb->priority)
+		return (-1);
+	else if (pa->priority < pb->priority)
+		return (1);
+
+	/* then sort by string */
+	return (strcmp(pa->descr, pb->descr));
+}
+
+static int
+bitrev16(int input)
+{
+	int retval = 0;
+	int x;
+
+	for (x = 0; x != 16; x++) {
+		if ((input >> x) & 1)
+			retval |= (0x8000 >> x);
+	}
+	return (retval);
+}
+
 static void
 search_hints(const char *bus, const char *dev, const char *pnpinfo)
 {
@@ -367,9 +404,20 @@ search_hints(const char *bus, const char *dev, const char *pnpinfo)
 					printf("\n");
 				else if (!notme) {
 					if (!unbound_flag) {
+						char *descr = NULL;
+
 						if (all_flag)
-							printf("%s: ", *dev ? dev : "unattached" );
-						printf("%s\n", lastmod);
+							asprintf(&descr, "%s: %s", *dev ? dev : "unattached", lastmod);
+						else
+							asprintf(&descr, "%s", lastmod);
+
+						if (descr != NULL && hit_index < DEVMATCH_MAX_HITS) {
+							match_data[hit_index].descr = descr;
+							match_data[hit_index].priority = bitrev16(mask);
+							hit_index++;
+						} else {
+							free(descr);
+						}
 					}
 					found++;
 				}
@@ -382,6 +430,19 @@ search_hints(const char *bus, const char *dev, const char *pnpinfo)
 		}
 		walker = (void *)(len - sizeof(int) + (intptr_t)walker);
 	}
+	if (hit_index != 0) {
+		/* sort hits by priority */
+		mergesort(match_data, hit_index, sizeof(match_data[0]), &match_data_compare);
+
+		/* printout */
+		for (i = 0; i != hit_index; i++) {
+			puts(match_data[i].descr);
+			free(match_data[i].descr);
+		}
+
+		/* reset hit_index */
+		hit_index = 0;
+	}       
 	if (unbound_flag && found == 0 && *pnpinfo) {
 		if (verbose_flag)
 			printf("------------------------- ");