linux-kernel - Re: [BUG REPORT] use of unreachable() masks uninitialized variables warnings

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Message-ID: <CAO6TR8Wh0wxQ3TWXEa4YNWm1xpQwovHQkO_3LQLcxpWx2PmDzg@mail.gmail.com>
Date:	Thu, 11 Feb 2016 21:28:18 -0700
From:	Jeff Merkey <linux.mdb@...il.com>
To:	"Theodore Ts'o" <tytso@....edu>, Jeff Merkey <linux.mdb@...il.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [BUG REPORT] use of unreachable() masks uninitialized variables warnings

> In your case, for example, I looked through several dozen warnings,
> and they were ***all*** bogus.  Keep in mind that this might make me
> less inclined to pay attention to complaints from you in the future.
> The story of the buy who cried wolf too often comes to mind.
>
> Perhaps you could actually take a close look at the warnings, before
> you fire off an e-mail?  If at least one of the warnings were valid
> and pointed at an actual bug, it wouldn't have been a complete waste
> of my time....
>

I did take a close look at some of them (I reviewed them in assembler
-- probably a closer look than you gave them) and it was somewhat
confusing since the compiler was outputing jmp labels in the wrong
places in the code after I removed the calls to unreachable().

Ted, that's the problem with sitting around looking at C code all day
trying to find bugs created by the linux macros with assembler output
that does not map precisely to the C code.  I discovered this grepping
around in the assembler output of these macro H libs.

If you like I can go over all the garbage assembler this gcc issue
generates around these BUG() macros with calls to unreachable which is
why I raised the issue.

Jeff