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From: Greg KH <gregkh@linuxfoundation.org>
To: Luis Chamberlain <mcgrof@kernel.org>
Cc: tj@kernel.org, shuah@kernel.org, akpm@linux-foundation.org,
	rafael@kernel.org, davem@davemloft.net, kuba@kernel.org,
	ast@kernel.org, andriin@fb.com, daniel@iogearbox.net,
	atenart@kernel.org, alobakin@pm.me, weiwan@google.com,
	ap420073@gmail.com, jeyu@kernel.org, ngupta@vflare.org,
	sergey.senozhatsky.work@gmail.com, minchan@kernel.org,
	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, netdev@vger.kernel.org,
	linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 4/4] test_sysfs: demonstrate deadlock fix
Date: Sat, 3 Jul 2021 06:49:46 +0200	[thread overview]
Message-ID: <YN/sar6nGeSCn89/@kroah.com> (raw)
In-Reply-To: <20210703004632.621662-5-mcgrof@kernel.org>

On Fri, Jul 02, 2021 at 05:46:32PM -0700, Luis Chamberlain wrote:
> +#define MODULE_DEVICE_ATTR_FUNC_STORE(_name) \
> +static ssize_t module_ ## _name ## _store(struct device *dev, \
> +				   struct device_attribute *attr, \
> +				   const char *buf, size_t len) \
> +{ \
> +	ssize_t __ret; \
> +	if (!try_module_get(THIS_MODULE)) \
> +		return -ENODEV; \
> +	__ret = _name ## _store(dev, attr, buf, len); \
> +	module_put(THIS_MODULE); \
> +	return __ret; \
> +}

As I have pointed out before, doing try_module_get(THIS_MODULE) is racy
and should not be added back to the kernel tree.  We got rid of many
instances of this "bad pattern" over the years, please do not encourage
it to be added back as others will somehow think that it correct code.

I'll go over the rest of this after 5.14-rc1 is out, am busy until then.

thanks,

greg k-h

  reply	other threads:[~2021-07-03  4:49 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-03  0:46 [PATCH v2 0/4] selftests: add a new test driver for sysfs Luis Chamberlain
2021-07-03  0:46 ` [PATCH v2 1/4] selftests: add tests_sysfs module Luis Chamberlain
2021-07-21 11:32   ` Greg KH
2021-07-22 22:34     ` Luis Chamberlain
2021-07-23 10:38       ` Greg KH
2021-07-23 17:32         ` Luis Chamberlain
2021-07-03  0:46 ` [PATCH v2 2/4] kernfs: add initial failure injection support Luis Chamberlain
2021-07-03  0:46 ` [PATCH v2 3/4] test_sysfs: add support to use kernfs failure injection Luis Chamberlain
2021-07-03  0:46 ` [PATCH v2 4/4] test_sysfs: demonstrate deadlock fix Luis Chamberlain
2021-07-03  4:49   ` Greg KH [this message]
2021-07-03 17:28     ` Luis Chamberlain
2021-07-21 11:33       ` Greg KH
2021-07-22 22:36         ` Luis Chamberlain

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