From: "H. Peter Anvin" <hpa@zytor.com>
To: Pete Zaitcev <zaitcev@redhat.com>
Cc: linux-raid@vger.kernel.org, mingo@redhat.com, dledford@redhat.com
Subject: Re: Curious code in autostart_array
Date: Thu, 22 Jun 2006 21:11:52 -0700 [thread overview]
Message-ID: <449B6A08.4080506@zytor.com> (raw)
In-Reply-To: <20060622210521.0aa68ec6.zaitcev@redhat.com>
Pete Zaitcev wrote:
> Hi, guys:
>
> My copy of 2.6.17-rc5 has the following code in autostart_array():
> mdp_disk_t *desc = sb->disks + i;
> dev_t dev = MKDEV(desc->major, desc->minor);
>
> if (!dev)
> continue;
> if (dev == startdev)
> continue;
> if (MAJOR(dev) != desc->major || MINOR(dev) != desc->minor)
> continue;
>
> Under what conditions do you think the last if() statement can fire?
> What is its purpose? This looks like an attempt to detect bit clipping.
> But what exactly?
>
It can fire if either desc->major or desc->minor overflow the respective
fields in dev_t. Unfortunately, it's not guaranteed to do so.
-hpa
next prev parent reply other threads:[~2006-06-23 4:11 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-06-23 4:05 Curious code in autostart_array Pete Zaitcev
2006-06-23 4:11 ` H. Peter Anvin [this message]
2006-06-23 4:46 ` Neil Brown
2006-06-23 5:25 ` Pete Zaitcev
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