linux-kernel - [PATCH v2] ftrace/module: Move ftrace_release_mod to ddebug

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Date:   Tue, 12 Dec 2017 17:24:32 +0530
From:   Namit Gupta <gupta.namit@...sung.com>
To:     rostedt@...dmis.org
Cc:     mingo@...hat.com, linux-kernel@...r.kernel.org,
        pankaj.m@...sung.com, a.sahrawat@...sung.com,
        Namit Gupta <gupta.namit@...sung.com>
Subject: [PATCH v2] ftrace/module: Move ftrace_release_mod to ddebug_cleanup
 label

ftrace_module_init happen after dynamic_debug_setup, it is desired that
cleanup should be called after this label however in current implementation
it is called in free module label,ie:even though ftrace in not initialized,
from so many fail case ftrace_release_mod() will be called and unnecessary
traverse the whole list.
In below patch we moved ftrace_release_mod() from free_module label to
ddebug_cleanup label. that is the best possible location, other solution
is to make new label to ftrace_release_mod() but since ftrace_module_init()
is not return with minimum changes it should be in ddebug_cleanup label.

Signed-off-by: Namit Gupta <gupta.namit@...sung.com>

---
 kernel/module.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/kernel/module.c b/kernel/module.c
index 0d1cb8d..4be966a 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -3523,6 +3523,7 @@ static int load_module(struct load_info *info, const char __user *uargs,
 	unset_module_core_ro_nx(mod);

  ddebug_cleanup:
+	ftrace_release_mod(mod);
 	dynamic_debug_remove(info->debug);
 	synchronize_sched();
 	kfree(mod->args);
@@ -3541,12 +3542,6 @@ static int load_module(struct load_info *info, const char __user *uargs,
 	synchronize_rcu();
 	mutex_unlock(&module_mutex);
  free_module:
-	/*
-	 * Ftrace needs to clean up what it initialized.
-	 * This does nothing if ftrace_module_init() wasn't called,
-	 * but it must be called outside of module_mutex.
-	 */
-	ftrace_release_mod(mod);
 	/* Free lock-classes; relies on the preceding sync_rcu() */
 	lockdep_free_key_range(mod->module_core, mod->core_size);

-- 
1.9.1