tracing: uprobes: Cleanup __trace_uprobe_create() with __free()

Use __free() to cleanup ugly gotos in __trace_uprobe_create().

Link: https://lore.kernel.org/all/175509540482.193596.6541098946023873304.stgit@devnote2/

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

kernel/trace/trace_uprobe.c

@@ -533,22 +533,25 @@ static int register_trace_uprobe(struct trace_uprobe *tu)
 	return ret;
 }
 
+DEFINE_FREE(free_trace_uprobe, struct trace_uprobe *, if (_T) free_trace_uprobe(_T))
+
 /*
  * Argument syntax:
  *  - Add uprobe: p|r[:[GRP/][EVENT]] PATH:OFFSET[%return][(REF)] [FETCHARGS]
  */
 static int __trace_uprobe_create(int argc, const char **argv)
 {
+	struct trace_uprobe *tu __free(free_trace_uprobe) = NULL;
 	const char *trlog __free(trace_probe_log_clear) = NULL;
 	const char *event = NULL, *group = UPROBE_EVENT_SYSTEM;
-	char *arg, *filename, *rctr, *rctr_end, *tmp;
+	struct path path __free(path_put) = {};
 	unsigned long offset, ref_ctr_offset;
+	char *filename __free(kfree) = NULL;
+	char *arg, *rctr, *rctr_end, *tmp;
 	char *gbuf __free(kfree) = NULL;
 	char *buf __free(kfree) = NULL;
 	enum probe_print_type ptype;
-	struct trace_uprobe *tu;
 	bool is_return = false;
-	struct path path;
 	int i, ret;
 
 	ref_ctr_offset = 0;
@@ -586,10 +589,8 @@ static int __trace_uprobe_create(int argc, const char **argv)
 
 	/* Find the last occurrence, in case the path contains ':' too. */
 	arg = strrchr(filename, ':');
-	if (!arg || !isdigit(arg[1])) {
-		kfree(filename);
+	if (!arg || !isdigit(arg[1]))
 		return -ECANCELED;
-	}
 
 	trace_probe_log_set_index(1);	/* filename is the 2nd argument */
 
@@ -597,13 +598,11 @@ static int __trace_uprobe_create(int argc, const char **argv)
 	ret = kern_path(filename, LOOKUP_FOLLOW, &path);
 	if (ret) {
 		trace_probe_log_err(0, FILE_NOT_FOUND);
-		kfree(filename);
 		return ret;
 	}
 	if (!d_is_reg(path.dentry)) {
 		trace_probe_log_err(0, NO_REGULAR_FILE);
-		ret = -EINVAL;
-		goto fail_address_parse;
+		return -EINVAL;
 	}
 
 	/* Parse reference counter offset if specified. */
@@ -611,16 +610,14 @@ static int __trace_uprobe_create(int argc, const char **argv)
 	if (rctr) {
 		rctr_end = strchr(rctr, ')');
 		if (!rctr_end) {
-			ret = -EINVAL;
 			rctr_end = rctr + strlen(rctr);
 			trace_probe_log_err(rctr_end - filename,
 					    REFCNT_OPEN_BRACE);
-			goto fail_address_parse;
+			return -EINVAL;
 		} else if (rctr_end[1] != '\0') {
-			ret = -EINVAL;
 			trace_probe_log_err(rctr_end + 1 - filename,
 					    BAD_REFCNT_SUFFIX);
-			goto fail_address_parse;
+			return -EINVAL;
 		}
 
 		*rctr++ = '\0';
@@ -628,7 +625,7 @@ static int __trace_uprobe_create(int argc, const char **argv)
 		ret = kstrtoul(rctr, 0, &ref_ctr_offset);
 		if (ret) {
 			trace_probe_log_err(rctr - filename, BAD_REFCNT);
-			goto fail_address_parse;
+			return ret;
 		}
 	}
 
@@ -640,8 +637,7 @@ static int __trace_uprobe_create(int argc, const char **argv)
 			is_return = true;
 		} else {
 			trace_probe_log_err(tmp - filename, BAD_ADDR_SUFFIX);
-			ret = -EINVAL;
-			goto fail_address_parse;
+			return -EINVAL;
 		}
 	}
 
@@ -649,7 +645,7 @@ static int __trace_uprobe_create(int argc, const char **argv)
 	ret = kstrtoul(arg, 0, &offset);
 	if (ret) {
 		trace_probe_log_err(arg - filename, BAD_UPROBE_OFFS);
-		goto fail_address_parse;
+		return ret;
 	}
 
 	/* setup a probe */
@@ -657,12 +653,12 @@ static int __trace_uprobe_create(int argc, const char **argv)
 	if (event) {
 		gbuf = kmalloc(MAX_EVENT_NAME_LEN, GFP_KERNEL);
 		if (!gbuf)
-			goto fail_mem;
+			return -ENOMEM;
 
 		ret = traceprobe_parse_event_name(&event, &group, gbuf,
 						  event - argv[0]);
 		if (ret)
-			goto fail_address_parse;
+			return ret;
 	}
 
 	if (!event) {
@@ -671,7 +667,7 @@ static int __trace_uprobe_create(int argc, const char **argv)
 
 		tail = kstrdup(kbasename(filename), GFP_KERNEL);
 		if (!tail)
-			goto fail_mem;
+			return -ENOMEM;
 
 		ptr = strpbrk(tail, ".-_");
 		if (ptr)
@@ -679,7 +675,7 @@ static int __trace_uprobe_create(int argc, const char **argv)
 
 		buf = kmalloc(MAX_EVENT_NAME_LEN, GFP_KERNEL);
 		if (!buf)
-			goto fail_mem;
+			return -ENOMEM;
 		snprintf(buf, MAX_EVENT_NAME_LEN, "%c_%s_0x%lx", 'p', tail, offset);
 		event = buf;
 		kfree(tail);
@@ -693,49 +689,37 @@ static int __trace_uprobe_create(int argc, const char **argv)
 		ret = PTR_ERR(tu);
 		/* This must return -ENOMEM otherwise there is a bug */
 		WARN_ON_ONCE(ret != -ENOMEM);
-		goto fail_address_parse;
+		return ret;
 	}
 	tu->offset = offset;
 	tu->ref_ctr_offset = ref_ctr_offset;
 	tu->path = path;
-	tu->filename = filename;
+	/* Clear @path so that it will not freed by path_put() */
+	memset(&path, 0, sizeof(path));
+	tu->filename = no_free_ptr(filename);
 
 	/* parse arguments */
 	for (i = 0; i < argc; i++) {
 		struct traceprobe_parse_context *ctx __free(traceprobe_parse_context)
 			= kzalloc(sizeof(*ctx), GFP_KERNEL);
 
-		if (!ctx) {
-			ret = -ENOMEM;
-			goto error;
-		}
+		if (!ctx)
+			return -ENOMEM;
 		ctx->flags = (is_return ? TPARG_FL_RETURN : 0) | TPARG_FL_USER;
 		trace_probe_log_set_index(i + 2);
 		ret = traceprobe_parse_probe_arg(&tu->tp, i, argv[i], ctx);
 		if (ret)
-			goto error;
+			return ret;
 	}
 
 	ptype = is_ret_probe(tu) ? PROBE_PRINT_RETURN : PROBE_PRINT_NORMAL;
 	ret = traceprobe_set_print_fmt(&tu->tp, ptype);
 	if (ret < 0)
-		goto error;
+		return ret;
 
 	ret = register_trace_uprobe(tu);
 	if (!ret)
-		goto out;
-
-error:
-	free_trace_uprobe(tu);
-out:
-	return ret;
-
-fail_mem:
-	ret = -ENOMEM;
-
-fail_address_parse:
-	path_put(&path);
-	kfree(filename);
+		tu = NULL;
 
 	return ret;
 }