tracing: Adopt __free() and guard() for trace_fprobe.c

Adopt __free() and guard() for trace_fprobe.c to remove gotos.

Link: https://lore.kernel.org/173708043449.319651.12242878905778792182.stgit@mhiramat.roam.corp.google.com
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

kernel/trace/trace_fprobe.c

@@ -416,6 +416,9 @@ static void free_trace_fprobe(struct trace_fprobe *tf)
 	}
 }
 
+/* Since alloc_trace_fprobe() can return error, check the pointer is ERR too. */
+DEFINE_FREE(free_trace_fprobe, struct trace_fprobe *, if (!IS_ERR_OR_NULL(_T)) free_trace_fprobe(_T))
+
 /*
  * Allocate new trace_probe and initialize it (including fprobe).
  */
@@ -426,7 +429,7 @@ static struct trace_fprobe *alloc_trace_fprobe(const char *group,
 					       struct module *mod,
 					       int nargs, bool is_return)
 {
-	struct trace_fprobe *tf;
+	struct trace_fprobe *tf __free(free_trace_fprobe) = NULL;
 	int ret = -ENOMEM;
 
 	tf = kzalloc(struct_size(tf, tp.args, nargs), GFP_KERNEL);
@@ -435,7 +438,7 @@ static struct trace_fprobe *alloc_trace_fprobe(const char *group,
 
 	tf->symbol = kstrdup(symbol, GFP_KERNEL);
 	if (!tf->symbol)
-		goto error;
+		return ERR_PTR(-ENOMEM);
 
 	if (is_return)
 		tf->fp.exit_handler = fexit_dispatcher;
@@ -447,13 +450,10 @@ static struct trace_fprobe *alloc_trace_fprobe(const char *group,
 
 	ret = trace_probe_init(&tf->tp, event, group, false, nargs);
 	if (ret < 0)
-		goto error;
+		return ERR_PTR(ret);
 
 	dyn_event_init(&tf->devent, &trace_fprobe_ops);
-	return tf;
+	return_ptr(tf);
-error:
-	free_trace_fprobe(tf);
-	return ERR_PTR(ret);
 }
 
 static struct trace_fprobe *find_trace_fprobe(const char *event,
@@ -880,14 +880,12 @@ static int register_trace_fprobe(struct trace_fprobe *tf)
 	struct trace_fprobe *old_tf;
 	int ret;
 
-	mutex_lock(&event_mutex);
+	guard(mutex)(&event_mutex);
 
 	old_tf = find_trace_fprobe(trace_probe_name(&tf->tp),
 				   trace_probe_group_name(&tf->tp));
-	if (old_tf) {
+	if (old_tf)
-		ret = append_trace_fprobe(tf, old_tf);
+		return append_trace_fprobe(tf, old_tf);
-		goto end;
-	}
 
 	/* Register new event */
 	ret = register_fprobe_event(tf);
@@ -897,7 +895,7 @@ static int register_trace_fprobe(struct trace_fprobe *tf)
 			trace_probe_log_err(0, EVENT_EXIST);
 		} else
 			pr_warn("Failed to register probe event(%d)\n", ret);
-		goto end;
+		return ret;
 	}
 
 	/* Register fprobe */
@@ -907,8 +905,6 @@ static int register_trace_fprobe(struct trace_fprobe *tf)
 	else
 		dyn_event_add(&tf->devent, trace_probe_event_call(&tf->tp));
 
-end:
-	mutex_unlock(&event_mutex);
 	return ret;
 }
 
@@ -1069,7 +1065,10 @@ static int parse_symbol_and_return(int argc, const char *argv[],
 	return 0;
 }
 
-static int __trace_fprobe_create(int argc, const char *argv[])
+DEFINE_FREE(module_put, struct module *, if (_T) module_put(_T))
+
+static int trace_fprobe_create_internal(int argc, const char *argv[],
+					struct traceprobe_parse_context *ctx)
 {
 	/*
 	 * Argument syntax:
@@ -1095,23 +1094,20 @@ static int __trace_fprobe_create(int argc, const char *argv[])
 	 * Type of args:
 	 *  FETCHARG:TYPE : use TYPE instead of unsigned long.
 	 */
-	struct trace_fprobe *tf = NULL;
+	struct trace_fprobe *tf __free(free_trace_fprobe) = NULL;
 	int i, new_argc = 0, ret = 0;
 	bool is_return = false;
-	char *symbol = NULL;
+	char *symbol __free(kfree) = NULL;
 	const char *event = NULL, *group = FPROBE_EVENT_SYSTEM;
-	const char **new_argv = NULL;
+	const char **new_argv __free(kfree) = NULL;
 	char buf[MAX_EVENT_NAME_LEN];
 	char gbuf[MAX_EVENT_NAME_LEN];
 	char sbuf[KSYM_NAME_LEN];
 	char abuf[MAX_BTF_ARGS_LEN];
-	char *dbuf = NULL;
+	char *dbuf __free(kfree) = NULL;
 	bool is_tracepoint = false;
-	struct module *tp_mod = NULL;
+	struct module *tp_mod __free(module_put) = NULL;
 	struct tracepoint *tpoint = NULL;
-	struct traceprobe_parse_context ctx = {
-		.flags = TPARG_FL_KERNEL | TPARG_FL_FPROBE,
-	};
 
 	if ((argv[0][0] != 'f' && argv[0][0] != 't') || argc < 2)
 		return -ECANCELED;
@@ -1121,13 +1117,11 @@ static int __trace_fprobe_create(int argc, const char *argv[])
 		group = TRACEPOINT_EVENT_SYSTEM;
 	}
 
-	trace_probe_log_init("trace_fprobe", argc, argv);
-
 	if (argv[0][1] != '\0') {
 		if (argv[0][1] != ':') {
 			trace_probe_log_set_index(0);
 			trace_probe_log_err(1, BAD_MAXACT);
-			goto parse_error;
+			return -EINVAL;
 		}
 		event = &argv[0][2];
 	}
@@ -1137,14 +1131,14 @@ static int __trace_fprobe_create(int argc, const char *argv[])
 	/* a symbol(or tracepoint) must be specified */
 	ret = parse_symbol_and_return(argc, argv, &symbol, &is_return, is_tracepoint);
 	if (ret < 0)
-		goto parse_error;
+		return -EINVAL;
 
 	trace_probe_log_set_index(0);
 	if (event) {
 		ret = traceprobe_parse_event_name(&event, &group, gbuf,
 						  event - argv[0]);
 		if (ret)
-			goto parse_error;
+			return -EINVAL;
 	}
 
 	if (!event) {
@@ -1160,49 +1154,44 @@ static int __trace_fprobe_create(int argc, const char *argv[])
 	}
 
 	if (is_return)
-		ctx.flags |= TPARG_FL_RETURN;
+		ctx->flags |= TPARG_FL_RETURN;
 	else
-		ctx.flags |= TPARG_FL_FENTRY;
+		ctx->flags |= TPARG_FL_FENTRY;
 
 	if (is_tracepoint) {
-		ctx.flags |= TPARG_FL_TPOINT;
+		ctx->flags |= TPARG_FL_TPOINT;
 		tpoint = find_tracepoint(symbol, &tp_mod);
 		if (tpoint) {
-			ctx.funcname = kallsyms_lookup(
+			ctx->funcname = kallsyms_lookup(
 				(unsigned long)tpoint->probestub,
 				NULL, NULL, NULL, sbuf);
 		} else if (IS_ENABLED(CONFIG_MODULES)) {
 				/* This *may* be loaded afterwards */
 				tpoint = TRACEPOINT_STUB;
-				ctx.funcname = symbol;
+				ctx->funcname = symbol;
 		} else {
 			trace_probe_log_set_index(1);
 			trace_probe_log_err(0, NO_TRACEPOINT);
-			goto parse_error;
+			return -EINVAL;
 		}
 	} else
-		ctx.funcname = symbol;
+		ctx->funcname = symbol;
 
 	argc -= 2; argv += 2;
 	new_argv = traceprobe_expand_meta_args(argc, argv, &new_argc,
-					       abuf, MAX_BTF_ARGS_LEN, &ctx);
+					       abuf, MAX_BTF_ARGS_LEN, ctx);
-	if (IS_ERR(new_argv)) {
+	if (IS_ERR(new_argv))
-		ret = PTR_ERR(new_argv);
+		return PTR_ERR(new_argv);
-		new_argv = NULL;
-		goto out;
-	}
 	if (new_argv) {
 		argc = new_argc;
 		argv = new_argv;
 	}
-	if (argc > MAX_TRACE_ARGS) {
+	if (argc > MAX_TRACE_ARGS)
-		ret = -E2BIG;
+		return -E2BIG;
-		goto out;
-	}
 
 	ret = traceprobe_expand_dentry_args(argc, argv, &dbuf);
 	if (ret)
-		goto out;
+		return ret;
 
 	/* setup a probe */
 	tf = alloc_trace_fprobe(group, event, symbol, tpoint, tp_mod,
@@ -1211,16 +1200,16 @@ static int __trace_fprobe_create(int argc, const char *argv[])
 		ret = PTR_ERR(tf);
 		/* This must return -ENOMEM, else there is a bug */
 		WARN_ON_ONCE(ret != -ENOMEM);
-		goto out;	/* We know tf is not allocated */
+		return ret;
 	}
 
 	/* parse arguments */
 	for (i = 0; i < argc; i++) {
 		trace_probe_log_set_index(i + 2);
-		ctx.offset = 0;
+		ctx->offset = 0;
-		ret = traceprobe_parse_probe_arg(&tf->tp, i, argv[i], &ctx);
+		ret = traceprobe_parse_probe_arg(&tf->tp, i, argv[i], ctx);
 		if (ret)
-			goto error;	/* This can be -ENOMEM */
+			return ret;	/* This can be -ENOMEM */
 	}
 
 	if (is_return && tf->tp.entry_arg) {
@@ -1231,7 +1220,7 @@ static int __trace_fprobe_create(int argc, const char *argv[])
 	ret = traceprobe_set_print_fmt(&tf->tp,
 			is_return ? PROBE_PRINT_RETURN : PROBE_PRINT_NORMAL);
 	if (ret < 0)
-		goto error;
+		return ret;
 
 	ret = register_trace_fprobe(tf);
 	if (ret) {
@@ -1242,29 +1231,32 @@ static int __trace_fprobe_create(int argc, const char *argv[])
 			trace_probe_log_err(0, BAD_PROBE_ADDR);
 		else if (ret != -ENOMEM && ret != -EEXIST)
 			trace_probe_log_err(0, FAIL_REG_PROBE);
-		goto error;
+		return -EINVAL;
 	}
 
-out:
+	/* 'tf' is successfully registered. To avoid freeing, assign NULL. */
-	if (tp_mod)
+	tf = NULL;
-		module_put(tp_mod);
+
+	return 0;
+}
+
+static int trace_fprobe_create_cb(int argc, const char *argv[])
+{
+	struct traceprobe_parse_context ctx = {
+		.flags = TPARG_FL_KERNEL | TPARG_FL_FPROBE,
+	};
+	int ret;
+
+	trace_probe_log_init("trace_fprobe", argc, argv);
+	ret = trace_fprobe_create_internal(argc, argv, &ctx);
 	traceprobe_finish_parse(&ctx);
 	trace_probe_log_clear();
-	kfree(new_argv);
-	kfree(symbol);
-	kfree(dbuf);
 	return ret;
-
-parse_error:
-	ret = -EINVAL;
-error:
-	free_trace_fprobe(tf);
-	goto out;
 }
 
 static int trace_fprobe_create(const char *raw_command)
 {
-	return trace_probe_create(raw_command, __trace_fprobe_create);
+	return trace_probe_create(raw_command, trace_fprobe_create_cb);
 }
 
 static int trace_fprobe_release(struct dyn_event *ev)