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Subject: Re: C++ pushback
From: Xavier Bestel <xavier.bestel@free.fr>
To: "J.A. Magallon" <jamagallon@able.es>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>,
       "Linux-Kernel," <linux-kernel@vger.kernel.org>
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Date: Tue, 25 Apr 2006 10:15:48 +0200
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On Tue, 2006-04-25 at 00:16, J.A. Magallon wrote:

> Tell me what is the difference between:
> 
> 
>     sbi = kmalloc(sizeof(*sbi), GFP_KERNEL);
>     if (!sbi)
>         return -ENOMEM;
>     sb->s_fs_info = sbi;
>     memset(sbi, 0, sizeof(*sbi));
>     sbi->s_mount_opt = 0;
>     sbi->s_resuid = EXT3_DEF_RESUID;
>     sbi->s_resgid = EXT3_DEF_RESGID;
> 
> and
> 
>     SuperBlock() : s_mount_opt(0), s_resuid(EXT3_DEF_RESUID), s_resgid(EXT3_DEF_RESGID)
>     {}
> 
>     ...
>     sbi = new SuperBlock;
>     if (!sbi)
>         return -ENOMEM;

In the first case you know that exactely *one* kmalloc(GFP_KERNEL)
occurs. In the second case you have to browse SuperBlock's constructor
to check if it allocates things, needs to run with/without interrupts,
PREEMPT, whatever... (not even talking about exceptions).

	Xav