perf tools: Do a few more directory handling optimizations

A few more optimizations for perf when dealing with directories.

Some of them significantly cut down the work which has to be
done. d_type should always be set; otherwise fix the kernel
code. And there are functions available to parse fstab-like
files, so use them.

Signed-off-by: Ulrich Drepper <drepper@redhat.com>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: a.p.zijlstra@chello.nl
Cc: acme@redhat.com
Cc: eranian@google.com
Cc: fweisbec@gmail.com
Cc: lizf@cn.fujitsu.com
Cc: paulus@samba.org
Cc: xiaoguangrong@cn.fujitsu.com
LKML-Reference: <200912192140.nBJLeSfA028905@hs20-bc2-1.build.redhat.com>
[ v2: two small stylistic fixlets ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>

tools/perf/builtin-kmem.c

@@ -92,23 +92,18 @@ static void setup_cpunode_map(void)
 	if (!dir1)
 		return;
 
-	while (true) {
-		dent1 = readdir(dir1);
-		if (!dent1)
-			break;
-
-		if (sscanf(dent1->d_name, "node%u", &mem) < 1)
+	while ((dent1 = readdir(dir1)) != NULL) {
+		if (dent1->d_type != DT_DIR ||
+		    sscanf(dent1->d_name, "node%u", &mem) < 1)
 			continue;
 
 		snprintf(buf, PATH_MAX, "%s/%s", PATH_SYS_NODE, dent1->d_name);
 		dir2 = opendir(buf);
 		if (!dir2)
 			continue;
-		while (true) {
-			dent2 = readdir(dir2);
-			if (!dent2)
-				break;
-			if (sscanf(dent2->d_name, "cpu%u", &cpu) < 1)
+		while ((dent2 = readdir(dir2)) != NULL) {
+			if (dent2->d_type != DT_LNK ||
+			    sscanf(dent2->d_name, "cpu%u", &cpu) < 1)
 				continue;
 			cpunode_map[cpu] = mem;
 		}

tools/perf/util/trace-event-info.c

@@ -20,6 +20,7 @@
  */
 #define _GNU_SOURCE
 #include <dirent.h>
+#include <mntent.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -103,28 +104,28 @@ static const char *find_debugfs(void)
 {
 	static char debugfs[MAX_PATH+1];
 	static int debugfs_found;
-	char type[100];
 	FILE *fp;
+	struct mntent *m;
 
 	if (debugfs_found)
 		return debugfs;
 
-	if ((fp = fopen("/proc/mounts","r")) == NULL)
+	fp = setmntent("/proc/mounts", "r");
+	if (!fp)
 		die("Can't open /proc/mounts for read");
 
-	while (fscanf(fp, "%*s %"
-		      STR(MAX_PATH)
-		      "s %99s %*s %*d %*d\n",
-		      debugfs, type) == 2) {
-		if (strcmp(type, "debugfs") == 0)
+	while ((m = getmntent(fp)) != NULL) {
+		if (strcmp(m->mnt_type, "debugfs") == 0) {
+			strcpy(debugfs, m->mnt_dir);
+			debugfs_found = 1;
 			break;
+		}
 	}
-	fclose(fp);
 
-	if (strcmp(type, "debugfs") != 0)
-		die("debugfs not mounted, please mount");
+	endmntent(fp);
 
-	debugfs_found = 1;
+	if (!debugfs_found)
+		die("debugfs not mounted, please mount");
 
 	return debugfs;
 }
@@ -317,7 +318,8 @@ static void copy_event_system(const char *sys, struct tracepoint_path *tps)
 		die("can't read directory '%s'", sys);
 
 	while ((dent = readdir(dir))) {
-		if (strcmp(dent->d_name, ".") == 0 ||
+		if (dent->d_type != DT_DIR ||
+		    strcmp(dent->d_name, ".") == 0 ||
 		    strcmp(dent->d_name, "..") == 0 ||
 		    !name_in_tp_list(dent->d_name, tps))
 			continue;
@@ -334,7 +336,8 @@ static void copy_event_system(const char *sys, struct tracepoint_path *tps)
 
 	rewinddir(dir);
 	while ((dent = readdir(dir))) {
-		if (strcmp(dent->d_name, ".") == 0 ||
+		if (dent->d_type != DT_DIR ||
+		    strcmp(dent->d_name, ".") == 0 ||
 		    strcmp(dent->d_name, "..") == 0 ||
 		    !name_in_tp_list(dent->d_name, tps))
 			continue;
@@ -394,26 +397,21 @@ static void read_event_files(struct tracepoint_path *tps)
 		die("can't read directory '%s'", path);
 
 	while ((dent = readdir(dir))) {
-		if (strcmp(dent->d_name, ".") == 0 ||
+		if (dent->d_type != DT_DIR ||
+		    strcmp(dent->d_name, ".") == 0 ||
 		    strcmp(dent->d_name, "..") == 0 ||
 		    strcmp(dent->d_name, "ftrace") == 0 ||
 		    !system_in_tp_list(dent->d_name, tps))
 			continue;
-		sys = malloc_or_die(strlen(path) + strlen(dent->d_name) + 2);
-		sprintf(sys, "%s/%s", path, dent->d_name);
-		ret = stat(sys, &st);
-		free(sys);
-		if (ret < 0)
-			continue;
-		if (S_ISDIR(st.st_mode))
-			count++;
+		count++;
 	}
 
 	write_or_die(&count, 4);
 
 	rewinddir(dir);
 	while ((dent = readdir(dir))) {
-		if (strcmp(dent->d_name, ".") == 0 ||
+		if (dent->d_type != DT_DIR ||
+		    strcmp(dent->d_name, ".") == 0 ||
 		    strcmp(dent->d_name, "..") == 0 ||
 		    strcmp(dent->d_name, "ftrace") == 0 ||
 		    !system_in_tp_list(dent->d_name, tps))
@@ -422,10 +420,8 @@ static void read_event_files(struct tracepoint_path *tps)
 		sprintf(sys, "%s/%s", path, dent->d_name);
 		ret = stat(sys, &st);
 		if (ret >= 0) {
-			if (S_ISDIR(st.st_mode)) {
-				write_or_die(dent->d_name, strlen(dent->d_name) + 1);
-				copy_event_system(sys, tps);
-			}
+			write_or_die(dent->d_name, strlen(dent->d_name) + 1);
+			copy_event_system(sys, tps);
 		}
 		free(sys);
 	}