From: David Laight <David.Laight@ACULAB.COM>
To: 'Zhouyang Jia' <jiazhouyang09@gmail.com>
Cc: Oleg Drokin <oleg.drokin@intel.com>,
Andreas Dilger <andreas.dilger@intel.com>,
James Simmons <jsimmons@infradead.org>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
NeilBrown <neilb@suse.com>,
Haneen Mohammed <hamohammed.sa@gmail.com>,
Al Viro <viro@zeniv.linux.org.uk>,
"Gustavo A. R. Silva" <garsilva@embeddedor.com>,
"lustre-devel@lists.lustre.org" <lustre-devel@lists.lustre.org>,
"devel@driverdev.osuosl.org" <devel@driverdev.osuosl.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH] staging: lustre: add error handling for try_module_get
Date: Wed, 13 Jun 2018 10:53:07 +0000 [thread overview]
Message-ID: <ed5d91f54b5a4776a66df87b645b0ee9@AcuMS.aculab.com> (raw)
In-Reply-To: <1528778968-42225-1-git-send-email-jiazhouyang09@gmail.com>
From: Zhouyang Jia
> Sent: 12 June 2018 05:49
>
> When try_module_get fails, the lack of error-handling code may
> cause unexpected results.
>
> This patch adds error-handling code after calling try_module_get.
...
> +++ b/drivers/staging/lustre/lnet/klnds/socklnd/socklnd.c
> @@ -2422,7 +2422,10 @@ ksocknal_base_startup(void)
>
> /* flag lists/ptrs/locks initialised */
> ksocknal_data.ksnd_init = SOCKNAL_INIT_DATA;
> - try_module_get(THIS_MODULE);
> + if (!try_module_get(THIS_MODULE)) {
> + CERROR("%s: cannot get module\n", __func__);
> + goto failed;
> + }
Can try_module_get(THIS_MODULE) ever fail?
Since you are running code in 'THIS_MODULE' the caller must have a
reference that can't go away.
So try_module_get() just increments the count that is already greater
than zero.
Similarly module_put(THIS_MODULE) must never be able to release the
last reference.
Any such calls that aren't in error paths after try_module_get() are
probably buggy.
David
next prev parent reply other threads:[~2018-06-13 10:52 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-12 4:49 [PATCH] staging: lustre: add error handling for try_module_get Zhouyang Jia
2018-06-12 5:26 ` NeilBrown
2018-06-12 6:31 ` Greg Kroah-Hartman
2018-06-13 10:53 ` David Laight [this message]
2018-06-13 12:02 ` NeilBrown
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