linux-kernel - Re: [PATCH] xen: fix: use WARN_ON instead of if condition followed by BUG.

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Message-ID: <20201230083408.b3p6hrk3fuyc332z@Air-de-Roger>
Date:   Wed, 30 Dec 2020 09:34:08 +0100
From:   Roger Pau Monné <roger.pau@...rix.com>
To:     YANG LI <abaci-bugfix@...ux.alibaba.com>
CC:     <boris.ostrovsky@...cle.com>, <jgross@...e.com>,
        <sstabellini@...nel.org>, <xen-devel@...ts.xenproject.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] xen: fix: use WARN_ON instead of if condition followed
 by BUG.

On Wed, Dec 30, 2020 at 02:38:06PM +0800, YANG LI wrote:
> Use WARN_ON instead of if condition followed by BUG in
> gnttab_batch_map() and gnttab_batch_copy().

But those are not equivalent as far as I'm aware. BUG will stop
execution, while WARN_ON will print a splat and continue executing.

If switching to WARN_ON is indeed fine it needs to be explained in the
commit message that returning to the caller(s) with
HYPERVISOR_grant_table_op having returned an error code is fine, and
that it's not going to create other issues, like memory corruption or
leaks.

Thanks, Roger.