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([2a09:80c0:192:0:20af:34be:985b:b6c8]) by smtp.gmail.com with ESMTPSA id e20-20020a5d5954000000b0021e42e7c7dbsm19557923wri.83.2022.08.25.02.58.48 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 25 Aug 2022 02:58:49 -0700 (PDT) Message-ID: Date: Thu, 25 Aug 2022 11:58:48 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.12.0 To: Joe Perches , linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, linux-doc@vger.kernel.org, kexec@lists.infradead.org, Linus Torvalds , Andrew Morton , Ingo Molnar , David Laight , Jonathan Corbet , Andy Whitcroft , Dwaipayan Ray , Lukas Bulwahn , Baoquan He , Vivek Goyal , Dave Young References: <20220824163100.224449-1-david@redhat.com> <20220824163100.224449-3-david@redhat.com> <3c250aa26020b2f336fd575a58d06ba26faf1f14.camel@perches.com> From: David Hildenbrand Organization: Red Hat Subject: Re: [PATCH RFC 2/2] checkpatch: warn on usage of VM_BUG_ON() and friends In-Reply-To: <3c250aa26020b2f336fd575a58d06ba26faf1f14.camel@perches.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1661421536; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=sXEuh/C7EhMT4N5IVCTMgJSlHVPtxpuWjvzgdztQOwA=; b=kNulyQAhJMzEwlXrzLCDtF+R5K5/dvon8+yweDIl6qFNK7Q4ITpVahBdNcBbBjZ3piIlMm YQsT4GXUDoRaE0cXWD50OABFwb3He6RBIKmBUtCvLtJswD51SAQvLStncYg7Xj/m/yj1O6 4fWxTz6KqKwpMnu1sYHMrzUuTajcR6k= ARC-Authentication-Results: i=1; imf09.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=FyYafbFk; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf09.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1661421536; a=rsa-sha256; cv=none; b=FwF+HfvMS5Bfk7yNFFu7Eg0OrsD4V5FxBHN+5l40RZDKsbvROURbxNLKGlNHIdlLnqJqqR 26DfR3d2IoJg46c5jiBOwbWcqZvDtDj6ZlgBEr2Xdc+GjyzxK4UICHtDgBb06+5HXndkz+ UOhCbWqEdq6H/UQFov5HtJj20k+ia5A= Authentication-Results: imf09.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=FyYafbFk; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf09.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com X-Rspam-User: X-Rspamd-Queue-Id: 0E2DD140007 X-Rspamd-Server: rspam10 X-Stat-Signature: cfey1ychux8o3memqsxpcxfermg5dhwn X-HE-Tag: 1661421532-158496 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 > Trying to find more possible variants and exceptions $ git grep -h -o -E "\b[a-zA-Z]+_BUG(_ON(_[a-zA-Z]+)*)?\(" | sort | uniq AA_BUG( -> Ok, no BUG() ASM_BUG( -> Bad BUILD_BUG( BUILD_BUG_ON( BUILD_BUG_ON_INVALID( BUILD_BUG_ON_MSG( BUILD_BUG_ON_ZERO( -> Ok CI_BUG_ON( -> Bad with CONFIG_DRM_I915_DEBUG DCCP_BUG( DCCP_BUG_ON( -> Ok, no BUG() do_BUG( -> BUG implementation, ok. GEM_BUG_ON( -> Bad with CONFIG_DRM_I915_DEBUG_GEM_ONCE GLOCK_BUG_ON( -> Bad handle_BUG( -> BUG implementation, ok. IDA_BUG_ON( KVM_BUG( KVM_BUG_ON( -> Ok, no BUG() lkdtm_BUG( paravirt_BUG( -> bad PROM_BUG( -> unused, will remove RWLOCK_BUG_ON( -> Ok, no BUG() snd_BUG( snd_BUG_ON( -> Ok, no BUG() SNIC_BUG_ON( -> Bad SPIN_BUG_ON( -> Ok, no BUG() UNWINDER_BUG( UNWINDER_BUG_ON( VIRTUAL_BUG_ON( VM_BUG_ON( VM_BUG_ON_FOLIO( VM_BUG_ON_MM( VM_BUG_ON_PAGE( VM_BUG_ON_PGFLAGS( VM_BUG_ON_VMA( XA_BUG_ON( -> Bad So an extended versions of your proposal like (ignoring do_BUG and handle_BUG, people are smart enough to figure that out) if ($line =~ /\b(?!AA_|BUILD_|DCCP_|IDA_|KVM_|RWLOCK_|snd_|SPIN_)(?:[a-zA-Z_]*_)?BUG(?:_ON)?(?:_[A-Z_]+)?\s*\(/ ? -- Thanks, David / dhildenb