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

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Date:   Thu, 28 Dec 2017 05:14:19 +0000
From:   NAMIT GUPTA <gupta.namit@...sung.com>
To:     "rostedt@...dmis.org" <rostedt@...dmis.org>
CC:     "mingo@...hat.com" <mingo@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        PANKAJ MISHRA <pankaj.m@...sung.com>,
        AMIT SAHRAWAT <a.sahrawat@...sung.com>
Subject: RE: [PATCH v2] ftrace/module: Move ftrace_release_mod to
 ddebug_cleanup label

 
Hello Steve,

As per the discussion I sent patch v2.

Please find.

Thanks,
Namit Gupta


--------- Original Message ---------
Sender : NAMIT GUPTA <gupta.namit@...sung.com> ./Senior Chief Engineer/SRI-Delhi-Platform S/W 1 Team/Samsung Electronics
Date   : 2017-12-12 17:29 (GMT+5:30)
Title  : [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