linux-kernel - Re: [patch] pipe: Don't oops when pipe filesystem isn't mounted

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Message-ID: <Pine.LNX.4.64.0612110741010.12500@woody.osdl.org>
Date:	Mon, 11 Dec 2006 07:44:33 -0800 (PST)
From:	Linus Torvalds <torvalds@...l.org>
To:	Chuck Ebbert <76306.1226@...puserve.com>
cc:	linux-kernel <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...l.org>
Subject: Re: [patch] pipe: Don't oops when pipe filesystem isn't mounted

On Mon, 11 Dec 2006, Chuck Ebbert wrote:
>
> Prevent oops when an app tries to create a pipe while pipefs
> is not mounted.

Have you actually seen this, or is this just from looking at code?

Quite frankly, if "pipe_mnt" is ever NULL, we're dead for lots of other 
reasons. 

In fact, pipe_mnt can't be NULL. The way it is initialized is:

	pipe_mnt = kern_mount(&pipe_fs_type);

and pipe_mnt doesn't even return NULL - it returns an error pointer, so if 
"kern_mount()" were to have failed, pipe_mnt will be some random invalid 
pointer that could only be tested with IS_ERR(), not by comparing against 
NULL.

But more fundamentally - we might as well oops. We need to panic or oops 
or do _something_ bad at some point anyway, because it's MUCH better to 
fail spectacularly than it would be to just silently fail without a pipe.

Hmm?

		Linus
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