checkpatch: warn on usage of VM_BUG_ON() and other BUG variants

davidhildenbrand · Jonathan Corbet · commit 69d517e6e210 · 2022-09-29T13:20:53.000-06:00
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> Link: https://lore.kernel.org/r/20220923113426.52871-3-david@redhat.com Signed-off-by: Jonathan Corbet <corbet@lwn.net>
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
@@ -4695,12 +4695,12 @@ sub process {
 			}
 		}
 
-# avoid BUG() or BUG_ON()
-		if ($line =~ /\b(?:BUG|BUG_ON)\b/) {
+# do not use BUG() or variants
+		if ($line =~ /\b(?!AA_|BUILD_|DCCP_|IDA_|KVM_|RWLOCK_|snd_|SPIN_)(?:[a-zA-Z_]*_)?BUG(?:_ON)?(?:_[A-Z_]+)?\s*\(/) {
 			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 absolutely unavoidable--use WARN_ON_ONCE() plus recovery code (if feasible) instead of BUG() or variants\n" . $herecurr);
 		}
 
 # avoid LINUX_VERSION_CODE

Original file line number	Diff line number	Diff line change
`@@ -4695,12 +4695,12 @@ sub process {`
`4695`	`4695`	`}`
`4696`	`4696`	`}`
`4697`	`4697`
`4698`		`-# avoid BUG() or BUG_ON()`
`4699`		`- if ($line =~ /\b(?:BUG\|BUG_ON)\b/) {`
	`4698`	`+# do not use BUG() or variants`
	`4699`	`+ if ($line =~ /\b(?!AA_\|BUILD_\|DCCP_\|IDA_\|KVM_\|RWLOCK_\|snd_\|SPIN_)(?:[a-zA-Z_]_)?BUG(?:_ON)?(?:_[A-Z_]+)?\s\(/) {`
`4700`	`4700`	`my $msg_level = \&WARN;`
`4701`	`4701`	`$msg_level = \&CHK if ($file);`
`4702`	`4702`	`&{$msg_level}("AVOID_BUG",`
`4703`		`- "Avoid crashing the kernel - try using WARN_ON & recovery code rather than BUG() or BUG_ON()\n" . $herecurr);`
	`4703`	`+ "Do not crash the kernel unless it is absolutely unavoidable--use WARN_ON_ONCE() plus recovery code (if feasible) instead of BUG() or variants\n" . $herecurr);`
`4704`	`4704`	`}`
`4705`	`4705`
`4706`	`4706`	`# avoid LINUX_VERSION_CODE`