From: John Hubbard <jhubbard@nvidia.com>
To: David Hildenbrand <david@redhat.com>, linux-kernel@vger.kernel.org
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>,
Baoquan He <bhe@redhat.com>,
linux-doc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
Dave Young <dyoung@redhat.com>, Jonathan Corbet <corbet@lwn.net>,
Nicholas Piggin <npiggin@gmail.com>,
Jani Nikula <jani.nikula@linux.intel.com>,
linux-mm@kvack.org, David Laight <David.Laight@ACULAB.COM>,
Dwaipayan Ray <dwaipayanray1@gmail.com>,
Andy Whitcroft <apw@canonical.com>, Joe Perches <joe@perches.com>,
Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Ingo Molnar <mingo@kernel.org>, Vivek Goyal <vgoyal@redhat.com>
Subject: Re: [PATCH v1 3/3] checkpatch: warn on usage of VM_BUG_ON() and other BUG variants
Date: Thu, 22 Sep 2022 19:05:54 -0700 [thread overview]
Message-ID: <d0c59eb8-baca-26fd-5f10-4a1f89bcf7b9@nvidia.com> (raw)
In-Reply-To: <20220920122302.99195-4-david@redhat.com>
On 9/20/22 05:23, David Hildenbrand wrote:
> checkpatch does not point out that VM_BUG_ON() and friends should be
> avoided, however, Linus notes:
>
> VM_BUG_ON() has the exact same semantics as BUG_ON. It is literally
> no different, the only difference is "we can make the code smaller
> because these are less important". [1]
>
> So let's warn on VM_BUG_ON() and other BUG variants as well. While at it,
> make it clearer that the kernel really shouldn't be crashed.
>
> As there are some subsystem BUG macros that actually don't end up crashing
> the kernel -- for example, KVM_BUG_ON() -- exclude these manually.
>
> [1] https://lore.kernel.org/r/CAHk-=wg40EAZofO16Eviaj7mfqDhZ2gVEbvfsMf6gYzspRjYvw@mail.gmail.com
>
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
> scripts/checkpatch.pl | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> index 79e759aac543..21f3a79aa46f 100755
> --- a/scripts/checkpatch.pl
> +++ b/scripts/checkpatch.pl
> @@ -4695,12 +4695,12 @@ sub process {
> }
> }
>
> -# avoid BUG() or BUG_ON()
> - if ($line =~ /\b(?:BUG|BUG_ON)\b/) {
> +# do not use BUG() or variants
> + if ($line =~ /\b(?!AA_|BUILD_|DCCP_|IDA_|KVM_|RWLOCK_|snd_|SPIN_)(?:[a-zA-Z_]*_)?BUG(?:_ON)?(?:_[A-Z_]+)?\s*\(/) {
Should this be a separate patch? Adding a bunch of exceptions to the BUG() rules is
a separate and distinct thing from adding VM_BUG_ON() and other *BUG*() variants to
the mix.
> my $msg_level = \&WARN;
> $msg_level = \&CHK if ($file);
> &{$msg_level}("AVOID_BUG",
> - "Avoid crashing the kernel - try using WARN_ON & recovery code rather than BUG() or BUG_ON()\n" . $herecurr);
> + "Do not crash the kernel unless it is unavoidable - use WARN_ON_ONCE & recovery code (if reasonable) rather than BUG() or variants.\n" . $herecurr);
Here's a requested tweak, to clean up the output and fix punctuation:
"Avoid crashing the kernel--use WARN_ON_ONCE() plus recovery code (if feasible) instead of BUG() or variants.\n" . $herecurr);
thanks,
--
John Hubbard
NVIDIA
next prev parent reply other threads:[~2022-09-23 2:07 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-20 12:22 [PATCH v1 0/3] coding-style.rst: document BUG() and WARN() rules David Hildenbrand
2022-09-20 12:23 ` [PATCH v1 1/3] coding-style.rst: document BUG() and WARN() rules ("do not crash the kernel") David Hildenbrand
2022-09-21 4:40 ` Kalle Valo
2022-09-22 14:12 ` David Hildenbrand
2022-09-26 7:44 ` Kalle Valo
2022-10-04 12:32 ` David Hildenbrand
2022-09-22 13:43 ` Akira Yokosawa
2022-09-22 14:41 ` David Hildenbrand
2022-09-23 2:26 ` John Hubbard
2022-09-23 2:37 ` John Hubbard
2022-09-23 10:55 ` David Hildenbrand
2022-09-20 12:23 ` [PATCH v1 2/3] powerpc/prom_init: drop PROM_BUG() David Hildenbrand
2022-09-21 13:02 ` Michael Ellerman
2022-09-21 13:03 ` David Hildenbrand
2022-09-20 12:23 ` [PATCH v1 3/3] checkpatch: warn on usage of VM_BUG_ON() and other BUG variants David Hildenbrand
2022-09-23 2:05 ` John Hubbard [this message]
2022-09-23 2:11 ` Joe Perches
2022-09-23 2:20 ` John Hubbard
2022-09-23 10:58 ` David Hildenbrand
2022-10-04 13:24 ` (subset) [PATCH v1 0/3] coding-style.rst: document BUG() and WARN() rules Michael Ellerman
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