From: corbet@lwn.net (Jonathan Corbet)
To: Tejun Heo <htejun@gmail.com>
To: ebiederm@xmission.com, cornelia.huck@de.ibm.com, greg@kroah.com,
stern@rowland.harvard.edu, kay.sievers@vrfy.org,
linux-kernel@vger.kernel.org, rusty@rustcorp.com.au
Subject: Re: [PATCH 1/4] module: implement module_inhibit_unload()
Date: Mon, 24 Sep 2007 16:00:05 -0600 [thread overview]
Message-ID: <25380.1190671205@lwn.net> (raw)
In-Reply-To: Your message of "Thu, 20 Sep 2007 16:26:15 +0900." <11902731752708-git-send-email-htejun@gmail.com>
Hi, Tejun,
I was just looking over these changes...
> + /* Don't proceed till inhibition is lifted. */
> + add_wait_queue(&module_unload_wait, &wait);
> + set_current_state(TASK_UNINTERRUPTIBLE);
> + if (atomic_read(&module_unload_inhibit_cnt))
> + schedule();
> + __set_current_state(TASK_RUNNING);
> + remove_wait_queue(&module_unload_wait, &wait);
> +
> + mutex_lock(&module_mutex);
Maybe I'm missing something, but this looks racy to me. There's no
check after schedule() to see if module_unload_inhibit_cnt is really
zero, and nothing to keep somebody else from slipping in and raising it
again afterward.
Given your description of this tool as a "sledgehammer," might it not be
easier to just take and hold module_mutex for the duration of the unload
block?
jon
next prev parent reply other threads:[~2007-09-24 22:00 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-09-20 7:26 [PATCHSET 2/4] sysfs: allow suicide Tejun Heo
2007-09-20 7:26 ` [PATCH 2/4] sysfs: make the sysfs_addrm_cxt->removed list FIFO Tejun Heo
2007-09-20 7:26 ` [PATCH 4/4] sysfs: make suicidal nodes just do it directly Tejun Heo
2007-09-20 9:24 ` Cornelia Huck
2007-09-20 9:43 ` Tejun Heo
2007-09-28 13:54 ` Cornelia Huck
2007-09-28 14:27 ` Tejun Heo
2007-09-20 7:26 ` [PATCH 1/4] module: implement module_inhibit_unload() Tejun Heo
2007-09-24 22:00 ` Jonathan Corbet [this message]
2007-09-24 23:18 ` Tejun Heo
2007-09-24 23:42 ` Rusty Russell
2007-09-25 1:40 ` Tejun Heo
2007-09-25 2:12 ` Rusty Russell
2007-09-25 2:39 ` Tejun Heo
2007-09-25 3:21 ` Rusty Russell
2007-09-25 3:36 ` Tejun Heo
2007-09-25 4:38 ` Rusty Russell
2007-09-25 8:01 ` Cornelia Huck
2007-09-25 8:25 ` Tejun Heo
2007-09-25 8:36 ` Tejun Heo
2007-09-25 8:50 ` Rusty Russell
2007-09-25 14:05 ` Tejun Heo
2007-09-25 14:24 ` Alan Stern
2007-09-25 14:30 ` Tejun Heo
2007-09-25 15:09 ` Alan Stern
2007-09-25 23:15 ` Tejun Heo
2007-09-25 23:41 ` Rusty Russell
2007-09-26 1:42 ` Tejun Heo
2007-09-26 14:39 ` Alan Stern
2007-09-20 7:26 ` [PATCH 3/4] sysfs: care-free suicide for sysfs files Tejun Heo
2007-09-25 22:02 ` [PATCHSET 2/4] sysfs: allow suicide Greg KH
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