linux-kernel - Re: [PATCH v6 2/3] zram: fix deadlock with sysfs attribute usage and module removal

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Message-Id: <20210710122851.aae9783ae9b1a703d565cbec@linux-foundation.org>
Date:   Sat, 10 Jul 2021 12:28:51 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Luis Chamberlain <mcgrof@...nel.org>
Cc:     minchan@...nel.org, gregkh@...uxfoundation.org, jeyu@...nel.org,
        ngupta@...are.org, sergey.senozhatsky.work@...il.com,
        rafael@...nel.org, axboe@...nel.dk, tj@...nel.org, mbenes@...e.com,
        jpoimboe@...hat.com, tglx@...utronix.de, keescook@...omium.org,
        jikos@...nel.org, rostedt@...dmis.org, peterz@...radead.org,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 2/3] zram: fix deadlock with sysfs attribute usage
 and module removal

On Fri,  2 Jul 2021 17:19:57 -0700 Luis Chamberlain <mcgrof@...nel.org> 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; \
> +}

I assume that Greg's comments on try_module_get() are applicable here
also.