From: Jessica Yu <jeyu@redhat.com>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>,
Seth Jennings <sjenning@redhat.com>,
Jiri Kosina <jikos@kernel.org>, Vojtech Pavlik <vojtech@suse.com>,
Miroslav Benes <mbenes@suse.cz>, Petr Mladek <pmladek@suse.com>,
Steven Rostedt <rostedt@goodmis.org>,
live-patching@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: modules: set mod->state to GOING before going notifiers are called
Date: Thu, 10 Mar 2016 00:08:31 -0500 [thread overview]
Message-ID: <20160310050830.GA31620@packer-debian-8-amd64.digitalocean.com> (raw)
In-Reply-To: <87a8m7ko6j.fsf@rustcorp.com.au>
+++ Rusty Russell [10/03/16 13:57 +1030]:
>Jessica Yu <jeyu@redhat.com> writes:
>> In load_module(), the going notifiers are called during error handling
>> when an error occurs after the coming notifiers have already been called.
>> However, a module's state is still MODULE_STATE_COMING when the going
>> notifiers are called in the error path. To be consistent, also set
>> mod->state to MODULE_STATE_GOING before calling the going notifiers.
>>
>> Signed-off-by: Jessica Yu <jeyu@redhat.com>
>> ---
>> kernel/module.c | 3 +++
>> 1 file changed, 3 insertions(+)
>>
>> diff --git a/kernel/module.c b/kernel/module.c
>> index 1981ae0..9e80576 100644
>> --- a/kernel/module.c
>> +++ b/kernel/module.c
>> @@ -3494,6 +3494,9 @@ static int load_module(struct load_info *info, const char __user *uargs,
>> return do_init_module(mod);
>>
>> coming_cleanup:
>> + mutex_lock(&module_mutex);
>> + mod->state = MODULE_STATE_GOING;
>> + mutex_unlock(&module_mutex);
>> blocking_notifier_call_chain(&module_notify_list,
>> MODULE_STATE_GOING, mod);
>
>Actually, reviewing this patch makes me realize it is wrong.
>
>We rely on the state of the module being MODULE_STATE_COMING here:
>
> static inline int strong_try_module_get(struct module *mod)
> {
> BUG_ON(mod && mod->state == MODULE_STATE_UNFORMED);
> if (mod && mod->state == MODULE_STATE_COMING)
> return -EBUSY;
>
>We will just have to document that the notifier can be called with
>a module in MODULE_STATE_COMING if it never succeeded its
>initialization.
Ah, thanks for catching that. I think I remember seeing this conditional and
assuming it wouldn't be a problem since GOING modules would fail in
try_module_get() (as it is does not pass the module_is_live() test) and
subsequently strong_try_module_get() would also fail.. But, I think I ought to
review how module states interact before making a change like this, so, please
ignore this patch.
Jessica
next prev parent reply other threads:[~2016-03-10 5:08 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-09 22:13 [PATCH 0/3] Livepatch module notifier cleanup Jessica Yu
2016-03-09 22:13 ` [PATCH 1/3] modules: split part of complete_formation() into prepare_coming_module() Jessica Yu
2016-03-10 22:41 ` Josh Poimboeuf
2016-03-09 22:13 ` [PATCH 2/3] modules: set mod->state to GOING before going notifiers are called Jessica Yu
2016-03-10 3:27 ` Rusty Russell
2016-03-10 5:08 ` Jessica Yu [this message]
2016-03-09 22:13 ` [PATCH 3/3] livepatch/module: remove livepatch module notifier Jessica Yu
2016-03-10 22:45 ` Josh Poimboeuf
2016-03-10 3:27 ` [PATCH 0/3] Livepatch module notifier cleanup Rusty Russell
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20160310050830.GA31620@packer-debian-8-amd64.digitalocean.com \
--to=jeyu@redhat.com \
--cc=jikos@kernel.org \
--cc=jpoimboe@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=live-patching@vger.kernel.org \
--cc=mbenes@suse.cz \
--cc=pmladek@suse.com \
--cc=rostedt@goodmis.org \
--cc=rusty@rustcorp.com.au \
--cc=sjenning@redhat.com \
--cc=vojtech@suse.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).