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Subject: Re: [PATCH v3] ubifs: make ubifs_[get|set]xattr atomic
From: Artem Bityutskiy <dedekind1@gmail.com>
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To: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>, richard@nod.at,
 linux-mtd@lists.infradead.org
Date: Tue, 11 Aug 2015 15:57:15 +0300
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On Fri, 2015-08-07 at 14:07 +0800, Dongsheng Yang wrote:
> +	mutex_lock(&ui->ui_mutex);
>  	kfree(ui->data);
>  	ui->data = kmemdup(value, size, GFP_NOFS);
>  	if (!ui->data) {
> +		mutex_unlock(&ui->ui_mutex);
>  		err = -ENOMEM;
>  		goto out_free;
>  	}
>  	inode->i_size = ui->ui_size = size;
>  	ui->data_len = size;
> +	mutex_unlock(&ui->ui_mutex);


Just one note - should kmemdup() be called outside of the critical
section, to make is shorter (memory allocation is a potentially slow
operation)?

Something like:

buf = kmemdup()
mutex_lock()
kfree(ui->data)
ui->data = buf
mutex_unlock()

Artem.