linux-kernel - [PATCH RFC v3 2/4] module: avoid double ref drop on ro_after

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Message-Id: <20241108-modules-ro_after_init-v3-2-6dd041b588a5@samsung.com>
Date: Fri, 08 Nov 2024 17:12:14 +0100
From: Daniel Gomez via B4 Relay <devnull+da.gomez.samsung.com@...nel.org>
To: Luis Chamberlain <mcgrof@...nel.org>, Petr Pavlu <petr.pavlu@...e.com>, 
 Sami Tolvanen <samitolvanen@...gle.com>, 
 Christophe Leroy <christophe.leroy@...roup.eu>, 
 Thomas Gleixner <tglx@...utronix.de>, Jinjie Ruan <ruanjinjie@...wei.com>, 
 Jens Axboe <axboe@...nel.dk>
Cc: "Daniel Gomez (Samsung)" <d+samsung@...ces.com>, 
 linux-modules@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Daniel Gomez <da.gomez@...sung.com>
Subject: [PATCH RFC v3 2/4] module: avoid double ref drop on ro_after_init
 failure

From: Daniel Gomez <da.gomez@...sung.com>

Ensure the module reference is only dropped once in case we fail at
MOD_RO_AFTER_INIT case.

Signed-off-by: Daniel Gomez <da.gomez@...sung.com>
---
 kernel/module/main.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/module/main.c b/kernel/module/main.c
index e0b2a8d9e324..35a50ded64a6 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -2941,8 +2941,6 @@ static noinline int do_init_module(struct module *mod)
 	ftrace_free_mem(mod, mod->mem[MOD_INIT_TEXT].base,
 			mod->mem[MOD_INIT_TEXT].base + mod->mem[MOD_INIT_TEXT].size);
 	mutex_lock(&module_mutex);
-	/* Drop initial reference. */
-	module_put(mod);
 	trim_init_extable(mod);
 #ifdef CONFIG_KALLSYMS
 	/* Switch to core kallsyms now init is done: kallsyms may be walking! */
@@ -2951,6 +2949,8 @@ static noinline int do_init_module(struct module *mod)
 	ret = module_enable_rodata_ro(mod, true);
 	if (ret)
 		goto fail_mutex_unlock;
+	/* Drop initial reference. */
+	module_put(mod);
 	mod_tree_remove_init(mod);
 	module_arch_freeing_init(mod);
 	for_class_mod_mem_type(type, init) {

-- 
2.39.2