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Date: Wed, 24 Aug 2022 21:00:11 +0200 From: David Hildenbrand <david@...hat.com> To: Joe Perches <joe@...ches.com>, linux-kernel@...r.kernel.org Cc: linux-mm@...ck.org, linux-doc@...r.kernel.org, kexec@...ts.infradead.org, Linus Torvalds <torvalds@...ux-foundation.org>, Andrew Morton <akpm@...ux-foundation.org>, Ingo Molnar <mingo@...nel.org>, David Laight <David.Laight@...LAB.COM>, Jonathan Corbet <corbet@....net>, Andy Whitcroft <apw@...onical.com>, Dwaipayan Ray <dwaipayanray1@...il.com>, Lukas Bulwahn <lukas.bulwahn@...il.com>, Baoquan He <bhe@...hat.com>, Vivek Goyal <vgoyal@...hat.com>, Dave Young <dyoung@...hat.com> Subject: Re: [PATCH RFC 2/2] checkpatch: warn on usage of VM_BUG_ON() and friends On 24.08.22 18:52, Joe Perches wrote: > On Wed, 2022-08-24 at 18:31 +0200, 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 friends as well. While at it, make it >> clearer that the kernel really shouldn't be crashed. >> >> Note that there are some other *_BUG_ON flavors, but they are not all >> bad: for example, KVM_BUG_ON() only triggers a WARN_ON_ONCE and then >> flags KVM as being buggy, so we'll not care about them for now here. > [] >> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl > [] >> @@ -4695,12 +4695,12 @@ sub process { >> } >> } >> >> -# avoid BUG() or BUG_ON() >> - if ($line =~ /\b(?:BUG|BUG_ON)\b/) { >> +# do not use BUG(), BUG_ON(), VM_BUG_ON() and friends. >> + if ($line =~ /\b(?:BUG|BUG_ON|VM_BUG_ON|VM_BUG_ON_[A-Z]+)\b/) { > > Perhaps better as something like the below to pick up more variants > > if ($line =~ /\b(?!KVM_|BUILD_)(?:[A-Z_]*_)?BUG(?:_ON)?(?:_[A-Z_]+)?\s*\(/ ... then I'll have to scan the other cases if they do something similar as KVM. ... well, okay, I'll do it. :) > >> 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); > > and maybe: > > "Do not crash the kernel unless it is unavoidable - use WARN_ON_ONCE & recovery code (if reasonable) rather than BUG() or variants\n" . $herecurr); > > Yes, thanks! -- Thanks, David / dhildenb
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