From: Luis Chamberlain <mcgrof@kernel.org>
To: Greg KH <gregkh@linuxfoundation.org>
Cc: minchan@kernel.org, jeyu@kernel.org, ngupta@vflare.org,
sergey.senozhatsky.work@gmail.com, axboe@kernel.dk,
mbenes@suse.com, jpoimboe@redhat.com, tglx@linutronix.de,
keescook@chromium.org, jikos@kernel.org, rostedt@goodmis.org,
peterz@infradead.org, linux-block@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 2/3] zram: fix deadlock with sysfs attribute usage and driver removal
Date: Tue, 22 Jun 2021 08:27:13 -0700 [thread overview]
Message-ID: <20210622152713.fqwyuqpamwgaxomc@garbanzo> (raw)
In-Reply-To: <YNGUIzh7aR3C/Hoz@kroah.com>
On Tue, Jun 22, 2021 at 09:41:23AM +0200, Greg KH wrote:
> On Mon, Jun 21, 2021 at 04:36:34PM -0700, Luis Chamberlain wrote:
> > + ssize_t __ret; \
> > + if (!try_module_get(THIS_MODULE)) \
>
> try_module_get(THIS_MODULE) is always racy and probably does not do what
> you want it to do. You always want to get/put module references from
> code that is NOT the code calling these functions.
In this case, we want it to trump module removal if it succeeds. That's all.
> > + return -ENODEV; \
> > + __ret = _name ## _store(dev, attr, buf, len); \
> > + module_put(THIS_MODULE); \
>
> This too is going to be racy.
>
> While fun to poke at, I still think this is pointless.
If you have a better idea, which does not "DOS" module removal, please
let me know!
Luis
next prev parent reply other threads:[~2021-06-22 15:27 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-21 23:30 [PATCH v3 0/3] zram: fix few sysfs races Luis Chamberlain
2021-06-21 23:30 ` [PATCH v3 1/3] zram: fix crashes due to use of cpu hotplug multistate Luis Chamberlain
2021-06-22 7:39 ` Greg KH
2021-06-22 15:12 ` Luis Chamberlain
2021-06-21 23:36 ` [PATCH v3 2/3] zram: fix deadlock with sysfs attribute usage and driver removal Luis Chamberlain
2021-06-22 7:41 ` Greg KH
2021-06-22 15:27 ` Luis Chamberlain [this message]
2021-06-22 16:27 ` Greg KH
2021-06-22 16:40 ` Luis Chamberlain
2021-06-22 16:51 ` Greg KH
2021-06-22 17:00 ` Luis Chamberlain
2021-06-22 7:45 ` Greg KH
2021-06-22 16:32 ` Luis Chamberlain
2021-06-22 17:16 ` Greg KH
2021-06-22 17:27 ` Luis Chamberlain
2021-06-22 18:05 ` Greg KH
2021-06-22 19:57 ` Luis Chamberlain
2021-06-21 23:36 ` [PATCH v3 3/3] drivers/base/core: refcount kobject and bus on device attribute read / store Luis Chamberlain
2021-06-22 7:46 ` Greg KH
2021-06-22 16:44 ` Luis Chamberlain
2021-06-22 16:48 ` Greg KH
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