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From: Petr Mladek <pmladek@suse.com>
To: Jiri Kosina <jikos@kernel.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Miroslav Benes <mbenes@suse.cz>
Cc: Joe Lawrence <joe.lawrence@redhat.com>,
	Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>,
	Nicolai Stange <nstange@suse.de>,
	live-patching@vger.kernel.org, linux-kernel@vger.kernel.org,
	Petr Mladek <pmladek@suse.com>
Subject: [POC 18/23] module: Refactor add_unformed_module()
Date: Fri, 17 Jan 2020 16:03:18 +0100
Message-ID: <20200117150323.21801-19-pmladek@suse.com> (raw)
In-Reply-To: <20200117150323.21801-1-pmladek@suse.com>

The livepatching code will need to add another condition to avoid
waiting. Let's make the code slightly less hairy.

Of course, it is a matter of taste. The main ideas of refactoring:

  + Make it clear what happens when old->state == MODULE_STATE_LIVE.

  + Make it more clear when we are leaving the function immediately
    and when we are doing some extra actions.

  + Be able to add another check that has to be done outside
    module_mutex and can result into an immediate return.

Signed-off-by: Petr Mladek <pmladek@suse.com>
---
 kernel/module.c | 28 +++++++++++++++-------------
 1 file changed, 15 insertions(+), 13 deletions(-)

diff --git a/kernel/module.c b/kernel/module.c
index b3f11524f8f9..ac45d465ff23 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -3721,28 +3721,30 @@ static int add_unformed_module(struct module *mod)
 again:
 	mutex_lock(&module_mutex);
 	old = find_module_all(mod->name, strlen(mod->name), true);
+
 	if (old != NULL) {
-		if (old->state != MODULE_STATE_LIVE) {
-			/* Wait in case it fails to load. */
+		if (old->state == MODULE_STATE_LIVE) {
 			mutex_unlock(&module_mutex);
-			err = wait_event_interruptible(module_wq,
-					       finished_loading(mod->name));
-			if (err)
-				goto out_unlocked;
-			goto again;
+			return -EEXIST;
 		}
-		err = -EEXIST;
-		goto out;
+
+		/* Wait in case it fails to load. */
+		mutex_unlock(&module_mutex);
+		err = wait_event_interruptible(module_wq,
+					       finished_loading(mod->name));
+		if (err)
+			return err;
+
+		/* Did the load succeded or failed? */
+		goto again;
 	}
+
 	mod_update_bounds(mod);
 	list_add_rcu(&mod->list, &modules);
 	mod_tree_insert(mod);
-	err = 0;
 
-out:
 	mutex_unlock(&module_mutex);
-out_unlocked:
-	return err;
+	return 0;
 }
 
 static int complete_formation(struct module *mod, struct load_info *info)
-- 
2.16.4


  parent reply index

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-17 15:03 [POC 00/23] livepatch: Split livepatch module per-object Petr Mladek
2020-01-17 15:03 ` [POC 01/23] module: Allow to delete module also from inside kernel Petr Mladek
2020-01-21 11:11   ` Julien Thierry
2020-01-17 15:03 ` [POC 02/23] livepatch: Split livepatch modules per livepatched object Petr Mladek
2020-01-21 11:11   ` Julien Thierry
2020-01-28 12:16     ` Petr Mladek
2020-01-17 15:03 ` [POC 03/23] livepatch: Better checks of struct klp_object definition Petr Mladek
2020-01-21 11:27   ` Julien Thierry
2020-01-17 15:03 ` [POC 04/23] livepatch: Prevent loading livepatch sub-module unintentionally Petr Mladek
2020-04-03 17:54   ` Joe Lawrence
2020-01-17 15:03 ` [POC 05/23] livepatch: Initialize and free livepatch submodule Petr Mladek
2020-01-21 11:58   ` Julien Thierry
2020-01-17 15:03 ` [POC 06/23] livepatch: Enable the " Petr Mladek
2020-01-17 15:03 ` [POC 07/23] livepatch: Remove obsolete functionality from klp_module_coming() Petr Mladek
2020-01-17 15:03 ` [POC 08/23] livepatch: Automatically load livepatch module when the patch module is loaded Petr Mladek
2020-01-17 15:03 ` [POC 09/23] livepatch: Handle race when livepatches are reloaded during a module load Petr Mladek
2020-01-22 18:51   ` Julien Thierry
2020-01-17 15:03 ` [POC 10/23] livepatch: Handle modprobe exit code Petr Mladek
2020-01-17 15:03 ` [POC 11/23] livepatch: Safely detect forced transition when removing split livepatch modules Petr Mladek
2020-01-22 10:15   ` Julien Thierry
2020-01-17 15:03 ` [POC 12/23] livepatch: Automatically remove livepatch module when the object is freed Petr Mladek
2020-01-17 15:03 ` [POC 13/23] livepatch: Remove livepatch module when the livepatched module is unloaded Petr Mladek
2020-01-17 15:03 ` [POC 14/23] livepatch: Never block livepatch modules when the related module is being removed Petr Mladek
2020-01-17 15:03 ` [POC 15/23] livepatch: Prevent infinite loop when loading livepatch module Petr Mladek
2020-01-17 15:03 ` [POC 16/23] livepatch: Add patch into the global list early Petr Mladek
2020-01-17 15:03 ` [POC 17/23] livepatch: Load livepatches for modules when loading the main livepatch Petr Mladek
2020-01-17 15:03 ` Petr Mladek [this message]
2020-01-17 15:03 ` [POC 19/23] module/livepatch: Allow to use exported symbols from livepatch module for "vmlinux" Petr Mladek
2020-04-06 18:48   ` Joe Lawrence
2020-04-07  7:33     ` Miroslav Benes
2020-04-07 20:57       ` Joe Lawrence
2020-01-17 15:03 ` [POC 20/23] module/livepatch: Relocate local variables in the module loaded when the livepatch is being loaded Petr Mladek
2020-01-18 10:29   ` kbuild test robot
2020-04-03 18:00   ` Joe Lawrence
2020-01-17 15:03 ` [POC 21/23] livepatch: Remove obsolete arch_klp_init_object_loaded() Petr Mladek
2020-01-17 15:03 ` [POC 22/23] livepatch/module: Remove obsolete copy_module_elf() Petr Mladek
2020-04-03 18:03   ` Joe Lawrence
2020-01-17 15:03 ` [POC 23/23] module: Remove obsolete module_disable_ro() Petr Mladek

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