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Date: Mon, 15 Apr 2024 01:46:20 -0700
From: Christoph Hellwig <hch@infradead.org>
To: Greg KH <gregkh@linuxfoundation.org>
Cc: Christoph Hellwig <hch@infradead.org>, Alex Elder <elder@linaro.org>,
	corbet@lwn.net, workflows@vger.kernel.org,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Documentation: coding-style: don't encourage WARN*()
Message-ID: <ZhzpXOUeldwAzXxY@infradead.org>
References: <20240414170850.148122-1-elder@linaro.org>
 <ZhzgTeEHFF19N3UZ@infradead.org>
 <2024041544-fester-undead-7949@gregkh>
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In-Reply-To: <2024041544-fester-undead-7949@gregkh>

On Mon, Apr 15, 2024 at 10:35:21AM +0200, Greg KH wrote:
> On Mon, Apr 15, 2024 at 01:07:41AM -0700, Christoph Hellwig wrote:
> > No, this advice is wronger than wrong.  If you set panic_on_warn you
> > get to keep the pieces.  
> > 
> 
> But don't add new WARN() calls please, just properly clean up and handle
> the error.  And any WARN() that userspace can trigger ends up triggering
> syzbot reports which also is a major pain, even if you don't have
> panic_on_warn enabled.

Important distinction here:  WARN_ON_ONCE is for internal error
checking and absolutely intentional, and does not replace error
handling, that's why it passes the error value through.  OF course
it should not be trigger by user action.

> And I think the "do not use panic_on_warn" recommendation has been
> ignored, given the huge use of it by vendors who have enabled it (i.e.
> all Samsung phones and cloud servers).

Sucks for them.