Re: C++ pushback

["Alexander E. Patrakov" <patrakov@ums.usu.ru>]

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;
>
> apart that you don't get members initalized twice and get a shorter code :).

The second example is simply incorrect, because the operator new throws an 
exception when we run out of memory, instead of returning a null pointer.

So it has to be written as:

sbi = new SuperBlock;
/* The rest of code assumes that the sbi pointer is valid. If this was not the 
case, let's hope that the caller caught std::bad_alloc properly */

--
Alexander E. Patrakov

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/